Is proteinuric pre-eclampsia a different disease in primigravida

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					                                                                                       Clinical Science (1999) 97, 475–483 (Printed in Great Britain)   475

    Is proteinuric pre-eclampsia a different disease
                 in primigravida and multigravida?
Anne E. BARDEN*, Lawrence J. BEILIN*, Jackie RITCHIE*, Barry N. WALTERS†,
Dorothy GRAHAM* and Constantine A. MICHAEL†
*University Department of Medicine, University of Western Australia, and Western Australian Heart Research Institute,
Royal Perth Hospital, P.O. Box X2213, Perth, Western Australia 6847, Australia, and †University Department of Obstetrics
and Gynaecology, King Edward Memorial Hospital, Subiaco, Western Australia, Australia

A      B     S     T     R     A      C     T

           This study aimed to identify if the clinical features of proteinuric pre-eclampsia or the
           biochemical markers of endothelial dysfunction associated with this syndrome are altered
           according to parity in a direction that would suggest a different pathophysiology. Groups of
           27 primigravid and 35 multigravid women with pre-eclampsia (defined as blood pressure
              140/90 mmHg and 2j proteinuria) were studied ante-partum, and at 6 weeks and 6 months
           post-partum. Clinical markers of severity of pre-eclampsia, including blood pressure, markers
           of renal, hepatic and coagulatory function, and biochemical markers of endothelial dysfunction
           were measured. Fetal outcome was assessed by birthweight and birthweight percentile. Ante-
           partum systolic blood pressure was 10 mmHg higher in the primigravida, and this difference was
           independent of age and anti-hypertensive medication. Analysis of systolic blood pressure before
           and after delivery showed the primigravid women to have elevated systolic blood pressure over
           the whole time period (P 0.01). The primigravid women had more severe hepatic dysfunction,
           with elevated aspartate aminotransferase levels, but plasma creatinine, proteinuria, platelet
           counts and haematocrit were similar, indicating that renal and coagulatory function and plasma
           volume were affected to the same extent in the two groups and were independent of parity.
           Birthweight was similar in the two groups, and the percentage of infants weighing less than the
           10th centile for gestation was also similar. Biochemical markers of endothelial dysfunction,
           assessed by measuring the urinary prostacyclin metabolite 2,3-dinor-6-oxo-prostaglandin F1α and
           plasma endothelin 1, did not differ according to parity. There were no differences in a number
           of other biochemical markers of pre-eclampsia, including plasma albumin, uric acid, triacyl-
           glycerol, and total, low-density lipoprotein and high-density lipoprotein cholesterol. Basophil,
           monocyte and lymphocyte counts were elevated before delivery in primigravid women with pre-
           eclampsia. The differences in lymphocyte counts persisted post-partum. Further studies are
           required to clarify the role, if any, of monocytes, basophils and lymphocytes in the
           pathophysiology of pre-eclampsia. In conclusion, the elevated systolic blood pressure and raised
           aspartate aminotransferase levels observed in primigravida suggest a more severe form of pre-
           eclampsia. The lack of differences in birthweight and other biochemical and endothelial markers
           of severity of pre-eclampsia do not suggest a different pathophysiology ; however, the
           persistently higher white cell counts in the primigravid pre-eclamptics are of interest, and might
           reflect differences in immune responses in the two groups. We suggest that studies of the
           pathophysiology of pre-eclampsia should include multigravida, as long as there is adequate post-
           partum follow-up to exclude underlying disease.

Key words : hypertension, lymphocytes, monocytes, parity, pre-eclampsia, proteinuria.
Abbreviations : ANOVA, analysis of variance ; HDL, high-density lipoprotein ; LDL, low-density lipoprotein ; PGF α,
prostaglandin F α ; SBP, systolic blood pressure.
Correspondence : Dr Anne Barden (e-mail abarden!

                                                                      # 1999 The Biochemical Society and the Medical Research Society
476   A. E. Barden and others

      INTRODUCTION                                                      cocyte counts are not usually measured as part of the
                                                                        clinical management of pre-eclampsia, they were
      This study examines whether there are identifiable                 examined in the present study because they have been
      differences in pathophysiological features of proteinuric         shown to be consistently elevated in pre-eclampsia
      pre-eclampsia according to whether the condition occurs           [7,11–13], and because of the potential for activated
      in first or subsequent pregnancies. Although defined by             leucocytes or an altered lipid profile to contribute to
      elevated blood pressure and proteinuria, pre-eclampsia is         endothelial dysfunction [14,15]. Clinical markers of pre-
      a multisystem disorder with impairments of renal, hepatic         eclampsia were examined, taking into account familial
      and coagulatory function, and is also characterized by            and lifestyle factors that may have affected the measure-
      endothelial dysfunction [1]. Evidence suggesting that the         ments. Patients were studied at hospital admission and
      pathophysiology of primigravid pre-eclampsia may differ           twice after delivery to determine whether any differences
      from that observed in multigravida comes from studies             distinguishing the two groups persisted in the non-
      showing that the prevalence of pre-eclampsia in a first            pregnant state.
      pregnancy is 15 times greater than that for a full-term
      second pregnancy [2]. In addition, glomeruloendo-
      theliosis, which has been suggested to reflect an accurate
      clinical diagnosis of pre-eclampsia and which provides
      morphological evidence of renal endothelial damage, was           Subjects
      found to be much less common in multigravida who had              Altogether, 27 primigravid and 35 multigravid women
      pre-eclampsia [3]. Chesley [4] noted that multiparous             were recruited at the King Edward Memorial Hospital
      women who had eclampsia had an increased incidence of             between 1991 and 1995 for studies investigating the
      underlying disease, while Gleishner et al. [5] observed           pathophysiology of pre-eclampsia [7,11,12,16,17]. They
      that multipara with pre-eclampsia showed an earlier               gave their informed consent to participate in the study,
      increase in blood pressure and a greater weight gain than         which was approved by the King Edward Memorial
      primipara. In the same study, the offspring of pre-               Hospital for Women and the University of Western
      eclamptic multipara were smaller relative to those of             Australia ethics committees. Pre-eclampsia was defined
      multiparous controls than infants born to primipara.              as the development of blood pressure greater than 140\90
      These findings suggested to both sets of authors that the          mmHg after 20 weeks ’ gestation, combined with
      pathophysiology of pre-eclampsia may differ according             proteinuria of at least 2j, in women with no known
      to parity.                                                        history of hypertension or renal disease and whose blood
         A number of factors could contribute to pre-eclampsia          pressure had returned to normal levels by 6 months post-
      in multigravida ; these include altered paternity, con-           partum with no continuing proteinuria. All the women
      sistent with the immunological theory of an inappro-              were studied on referral to the research nurse prior to
      priate response to new paternal fetal antigens [6], and           delivery, and at 6 weeks and 6 months post-partum.
      acquired factors sensitizing patients to the disorder. It is
      likely that no single cause will explain all cases of pre-
      eclampsia, and that a number of different underlying              Assessment of obstetric and medical
      factors could operate to result in the development of pre-        history, family history of disease and
      eclampsia.                                                        lifestyle factors
         The present study aimed, first, to identify whether             At an antenatal visit, all the women answered a ques-
      there are clinical features of proteinuric pre-eclampsia          tionnaire relating to their obstetric and medical history,
      that distinguish primigravid from multigravid women,              including changes in paternity for multigravida, medi-
      suggesting a different pathophysiology. The parameters            cation usage and lifestyle habits, including alcohol con-
      examined included blood pressure and factors related to           sumption and smoking. An assessment of family history
      renal, hepatic and haematological abnormalities com-              of disease was made by administration of a questionnaire
      monly observed in the syndrome. As morphological                  that asked the women if they had any family history of
      evidence of glomeruloendotheliosis has been reported to           high blood pressure, stroke, diabetes or renal disease. If
      differ between primigravid and multigravid pre-                   they answered in the affirmative, they were asked
      eclamptics, a secondary aim was to examine biochemical            specifically which family member had been affected.
      markers of endothelial dysfunction. The markers                   Inquiry was also made into the obstetric history of each
      measured included urinary 2,3-dinor-6-oxo-prosta-                 subject’s mother and whether she had suffered from pre-
      glandin F α (2,3-dinor-6-oxo-PGF α), a marker of sys-             eclampsia, pregnancy-induced hypertension or toxaemia
                 "                         "
      temic prostacyclin synthesis, and plasma endothelin 1,            during any of her pregnancies. The women reported their
      both of which have been shown to be altered in pre-               current smoking habits and alcohol consumption in the
      eclampsia in a direction that suggests endothelial dys-           previous week. Statistical analysis was confined to
      function [7–10]. Although plasma lipid levels and leu-            Caucasian women who had no previous history of

      # 1999 The Biochemical Society and the Medical Research Society
                                                                                        Distinguishing features of primigravid pre-eclampsia   477

diabetes, hypertension or renal disease. Parity of the         Perth Hospital. A full blood screen, including platelet
subjects was determined from their medical records and         count and white blood cell differential, was obtained at
the questionnaire administered by a research nurse.            the Department of Haematology, Royal Perth Hospital,
Women who reported having terminations or spon-                using a Coulter Counter.
taneous abortions were classified as multigravida, and
their gravid status was confirmed by hospital records.          Biochemical markers of endothelial dysfunction
The multigravid women were asked if they had pre-              Systemic prostacyclin synthesis, which has been found
viously had pre-eclampsia, and whether they had a              previously to be reduced in women with pre-eclampsia,
different partner from the previous pregnancy.                 was assessed by measuring the urinary prostacyclin
                                                               metabolite 2,3-dinor-6-oxo-PGF α by radioimmuno-
                                                               assay after extraction and purification by TLC [7]. Plasma
Maternal clinical measurements
                                                               endothelin 1, which has been shown previously to be
Blood pressure and heart rate                                  raised in women with pre-eclampsia, was measured by
The women were enrolled in the study after hospital            radioimmunoassay after extraction, as described pre-
admission. Sixteen primigravida and 20 multigravida were       viously [7].
attending the antenatal clinics prior to admission and had
blood pressure recorded between 22 and 28 weeks ’              Fetal outcome measures
gestation as part of their clinical management. The            Details of infant birthweight and postnatal complications
remaining nine primigravida and 15 multigravida were           were obtained from hospital records. The baby’s birth-
referred from remote sites with a referral letter stating      weight percentile was determined using Australian
that their blood pressure during pregnancy had been            standardized birthweight scales that take into account
normal until the time of diagnosis and transfer. The           parity, the sex of the infant and the mother’s height.
blood pressure at admittance used for entry into the
study was the initial measurement recorded by the
resident doctor on the antenatal ward using a manual           Statistical analysis
sphygmomanometer. Upon entry into the study and at             Results are expressed as meanspS.E.M. Differences in
6 weeks and 6 months post-partum, blood pressure was           familial and lifestyle factors were assessed using Chi-
measured by the same research nurse using a Dinamap            square analysis. Differences between primigravida and
1846 SX oscillometric monitor. The women were studied          multigravida were assessed using an unpaired t-test or,
prior to delivery in the antenatal ward. Post-partum           where data were not normally distributed, the Mann–
study of the women took place at either the hospital           Whitney test. A Bonferroni correction was used to
outpatient clinic or the subject’s home. Systolic and          correct for multiple testing. Antepartum blood pressure
diastolic blood pressure and heart rate for each visit was     differences between the pre-eclamptic primigravida and
the average of six Dinamap readings taken at 1 min             multigravida were assessed by ANOVA (analysis of
intervals after 5 min of seated rest.                          variance) after adjustment for differences in age and
                                                               duration of anti-hypertensive treatment. Differences in
                                                               systolic blood pressure (SBP) over time were assessed by
Biochemical and haematological measurements                    unpaired t-test after calculation of the area under the
At each visit, 24 h urine was collected and a non-fasting      curve for primigravida and multigravida.
blood sample was obtained from the antecubital vein by
the research nurse, after 10 min of seated rest. Plasma uric
acid, albumin and urinary protein excretion were
measured as markers of severity of pre-eclampsia, using a
COVAS-MIRA analyser in the Biochemistry Depart-
                                                               The primigravid and multigravid women were studied at
ment, Royal Perth Hospital. Plasma creatinine was
                                                               similar gestations : 31.4p0.6 weeks in the primigravid
measured as a marker of renal impairment using the same
                                                               women and 30.8p0.6 weeks in multigravida. The primi-
instrument. In 23 of the primigravida and 26 of the
                                                               gravid women were, as expected, younger (Table 1).
multigravida, hepatic abnormalities were assessed ante-
natally as part of the patients ’ clinical management by
measuring aspartate aminotransferase and alkaline phos-        Differences in family history and lifestyle
phatase activities. Bilirubin levels were measured in the      factors in relation to parity
same patient subgroup. Plasma triacylglycerols and total,      The primigravid and multigravid women were similar
low-density lipoprotein (LDL) and high-density lipo-           with respect to family history of hypertension (64% primi-
protein (HDL) cholesterol were measured in a subgroup          gravida, 65.7 % multigravida), stroke (24 % primigravida,
of 18 primigravida and 20 multigravida using a COVAS-          22.9% multigravida), diabetes (28% primigravida, 28.6%
MIRA analyser in the Biochemistry Department at Royal          multigravida) and renal disease (0 % primigravida, 5 %

                                                               # 1999 The Biochemical Society and the Medical Research Society
478   A. E. Barden and others

      Table 1 Age, body mass index (BMI) and blood pressure
      before and after delivery, and anti-hypertensive treatment
      DBP, diastolic blood pressure. *P   0.01 for primigravid compared with
      multigravid pre-eclamptic women.

                                             Primigravida        Multigravida
      Age (years)                            25.9p0.9            28.7p1.2
      BMI (kg/m2)
         Ante-partum                         29.2p0.7            29.7p1.1
         6 weeks post-partum                 25.6p0.9            27.0p1.2
         6 months post-partum                26.6p1.0            26.1p1.3
      Admitting blood pressure (mmHg)                                           Figure 1 Individual ante-partum SBP values in primigravid
         SBP                                 159p3                152p4         and multigravid women with pre-eclampsia
         DBP                                  98p4                 99p2         The difference between groups is significant (ANOVA ; P 0.01) after correction
      Dinamap SBP (mmHg)                                                        for differences in age and duration of anti-hypertensive treatment.
         Ante-partum                         138p2*               128p2
         6 weeks post-partum                 116p2                113p2
         6 months post-partum                117p2                112p2
      Dinamap DBP (mmHg)
         Ante-partum                          78p2                 75p2
         6 weeks post-partum                  70p2                 70p2
         6 months post-partum                 70p2                 70p2
      Heart rate (beats/min)
         Ante-partum                          76p3                 83p3
         6 weeks post-partum                  78p2                 79p2
         6 months post-partum                 77p2                 78p2
      Anti-hypertensive treatment
         Treated                             56 % (15)           60 % (21)      Figure 2 Comparison of SBP area under the curve for
         Aspirin                              7 % (2)             0 % (0)       primigravid ($) and multigravid (
) women with pre-
                                                                                PP, post-partum. P l 0.015 for comparison between primigravid and multigravid
      multigravida). The reported family history of maternal                    women.
      pre-eclampsia was similar in the two groups (52.4 %
      primigravida, 38.5 % multigravida). Only one subject                      Blood pressure recorded by manual sphygmomanometer
      reported having changed partner since her last pregnancy.                 on admission to hospital showed a non-significant trend
      Of the multigravid women, 43 % reported that they had                     to higher levels in the primigravida. Antenatal SBP
      previously suffered from pregnancy-induced hyper-                         measured using a Dinamap recorder was significantly
      tension. The percentage of women currently smoking                        elevated in the primigravid women compared with the
      before delivery was similar in the primigravida and                       multigravid women (P l 0.004) (Figure 1, Table 1).
      multigravida (18.5 % and 12.1 % respectively), as was the                 Although SBP fell in both groups after delivery
      percentage that had consumed alcohol in the previous                      (examined as area under the curve before and after
      week (11.1 % of primigravida compared with 15.2 % of                      delivery), the primigravid women had significantly higher
      multigravida).                                                            SBPs compared with the multigravid women over the
                                                                                whole time period (P l 0.015) (Figure 2). Diastolic blood
      Differences in anthropometry, heart rate                                  pressure measured by Dinamap tended to be higher in the
      and blood pressure in relation to parity                                  primigravid women both before and after delivery, but
      There were no between-group differences in body mass                      the difference did not achieve statistical significance
      index or heart rate before delivery, or at 6 weeks or                     (Table 1).
      6 months post-partum (Table 1). Antenatal clinic blood                       The number of the women receiving anti-hypertensive
      pressures were obtained from medical records for the                      medication at the time they were studied was similar in
      period between 22 and 28 weeks ’ gestation, before the                    the two groups (Table 1). The treatment consisted mainly
      onset of clinical symptoms, and these averaged                            of α-methyldopa and nifedipine. For these reasons, the
      120\72p1.9\1.4 mmHg in the 16 primigravida and                            analysis was repeated using ANOVA with adjustment
      120\73p2.6\1.3 mmHg in the 20 multigravida assessed.                      for differences in age and duration of medication. The

      # 1999 The Biochemical Society and the Medical Research Society
                                                                                                 Distinguishing features of primigravid pre-eclampsia   479

              Table 2     Biochemical markers of pre-eclampsia in primigravid and multigravid women
              *P l 0.015 for primigravid compared with multigravid women.

                                                                        Primigravida                   Multigravida
                 Plasma aspartate aminotransferase (units/l)            53.1p9.6 (n l 26)*             26.2p6.9 (n l 31)
                 Plasma alkaline phosphatase (units/l)                   145p37.7 (n l 26)             139p6.9 (n l 31)
                 Bilirubin (µmol/l)                                      7.2p0.5 (n l 26)               7.6p0.7 (n l 31)
              Plasma albumin (g/l)
                  Ante-partum                                           31.2p0.6                       31.0p0.5
                  6 weeks post-partum                                   43.1p0.5                       42.4p0.5
                  6 months post-partum                                  43.4p0.6                       42.3p0.5
              Plasma creatinine (µmol/l)
                  Ante-partum                                           70.1p2.5                       70.4p2.1
                  6 weeks post-partum                                   71.3p1.8                       75.3p2.0
                  6 months post-partum                                  74.5p1.8                       76.7p2.4
              Plasma uric acid (mmol/l)
                  Ante-partum                                           0.38p0.02                      0.35p0.02
                  6 weeks post-partum                                   0.31p0.01                      0.30p0.01
                  6 months post-partum                                  0.27p0.01                      0.26p0.01
              Urinary protein (g/24 h)
                 Ante-partum                                            2.20p0.4                       1.60p0.4
                 6 weeks post-partum                                    0.20p0.03                      0.27p0.05
                 6 months post-partum                                   0.24p0.05                      0.20p0.04

10 mmHg difference in antenatal SBP was found to                           The blood pressure of multigravida was examined
persist after this adjustment (P l 0.004). The treated and              in terms of whether they had a history of previous
untreated primigravida and multigravida were similar                    pre-eclampsia. In those women reporting previous pre-
with respect to gestation at sampling, and the differences              eclampsia (n l 15), SBP was 127p3 mmHg, compared
in age were similar to those of the group as a whole. When              with 129p3 mmHg in those with no previous history
SBP was examined in terms of whether the women were                     (n l 20), while diastolic blood pressure was 75p
receiving anti-hypertensive treatment, the primigravid                  1.6 mmHg, compared with 75p2.4 mmHg in subjects
women had a significantly higher SBP regardless of                       with no previous history.
treatment. SBP was 134p3.5 mmHg in untreated primi-
gravida compared with 125p3.1 mmHg in untreated
multigravid women (P 0.05), while in the treated                        Effect of parity on biochemical and
primigravida SBP was 140p3.0 mmHg compared with                         haematological markers of pre-eclampsia
130p2.8 mmHg in treated multigravida (P 0.05). The                      There were no significant differences in plasma albumin,
duration of anti-hypertensive treatment before entry into               uric acid or creatinine, or urinary protein, between the
the study was 24 h or less in 86 % of primigravid women                 primigravid and multigravid women either before de-
and 75 % of multigravid women.                                          livery or at any post-partum visit (Table 2). Proteinuria
                                                                        was first detected at a similar stage of gestation in both
                                                                        groups. Prior to delivery, the primigravid women had
Examination of effects of family and                                    significantly higher levels of aspartate aminotransferase
obstetric history on blood pressure                                     activity compared with multigravida, with 11 of the 23
SBP was also examined in terms of those subjects who                    primigravid women having levels outside the normal
reported a family history of hypertension. In the primi-                limits for the measurement, compared with three of 26
gravid group, SBP was 140p3 mmHg in those with a                        measured in the multigravid group (Table 2). Antenatal
family history of hypertension (n l 16), compared with                  levels of alkaline phosphatase were raised compared with
134p4 mmHg in those with none (n l 9). In multigravid                   the normal range ; however, the levels were not affected
women, SBP was 127p3 mmHg in those women with a                         by parity. The levels of bilirubin were similar in primi-
family history (n l 23), compared with 129p3 mmHg in                    gravida and multigravida (Table 2). Although not used in
those with none (n l 12).                                               the clinical management of pre-eclampsia, plasma triacyl-

                                                                        # 1999 The Biochemical Society and the Medical Research Society
480   A. E. Barden and others

      Table 3 Markers of endothelial dysfunction and lipids in          Table 4 Haematological measures in primigravid and multi-
      primigravid and multigravid pre-eclamptic women                   gravid women with pre-eclampsia
                                                                        *P    0.05 for primigravid compared with multigravid women with pre-eclampsia.
                                         Primigravida    Multigravida
                                                                                                                  Primigravida        Multigravida
      Urinary 2,3-dinor-6-oxo-PGF1α
         Ante-partum                     1697p281        1696p379       Haemoglobin (g/l)
         6 weeks post-partum             1110p191        1540p424           Ante-partum                             119p2.1             117p2.1
         6 months post-partum            1208p328        1021p221           6 weeks post-partum                     129p1.5             129p1.5
      Plasma endothelin 1 (pg/ml)                                           6 months post-partum                    132p1.5             129p2.3
          Ante-partum                     8.4p1.5         7.0p1.0       Haematocrit (l/l)
          6 weeks post-partum             5.9p0.6         4.8p0.3           Ante-partum                           0.347p0.007         0.338p0.003
          6 months post-partum            6.1p0.7         5.3p0.5           6 weeks post-partum                   0.384p0.005         0.388p0.004
                                                                            6 months post-partum                  0.396p0.006         0.391p0.003
      Serum triacylglycerol (mmol/l)                                    Platelet count (109/l)
         Ante-partum                     3.51p0.34        3.29p0.29         Ante-partum                             229p14              253p15
         6 weeks post-partum             1.28p0.17        1.30p0.16         6 weeks post-partum                     332p16              317p15
         6 months post-partum            1.26p0.16        1.61p0.38         6 months post-partum                    339p20              316p23
      Serum cholesterol (mmol/l)                                        White cell count (109/l)
         Ante-partum                     6.99p0.41        7.22p0.42         Ante-partum                           13.22p0.75          11.58p0.57
         6 weeks post-partum             5.78p0.35        5.81p0.31         6 weeks post-partum                    7.12p0.38           6.77p0.29
         6 months post-partum            5.56p0.48        5.40p0.23         6 months post-partum                   7.32p0.28           6.25p0.32
      LDL cholesterol (mmol/l)                                          Neutrophils (109/l)
         Ante-partum                     3.55p0.29        3.96p0.36         Ante-partum                           10.26p0.76           9.04p0.53.4
         6 weeks post-partum             3.73p0.34        3.87p0.29         6 weeks post-partum                    4.00p0.31           4.07p0.26
         6 months post-partum            3.56p0.45        3.43p0.16         6 months post-partum                   4.21p0.19           3.75p0.29
                                                                        Lymphocytes (109/l)
      HDL cholesterol (mmol/l)                                              Ante-partum                             2.02p0.11*         1.74p0.16
         Ante-partum                     1.80p0.12        1.67p0.09         6 weeks post-partum                     2.31p0.09*         1.96p0.10
         6 weeks post-partum             1.47p0.08        1.33p0.06         6 months post-partum                    2.32p0.12*         1.79p0.08
         6 months post-partum            1.42p0.09        1.22p0.05     Monocytes (109/l)
                                                                            Ante-partum                             0.68p0.06*         0.50p0.05
                                                                            6 weeks post-partum                     0.39p0.03          0.36p0.01
      glycerols and cholesterol were measured because they                  6 months post-partum                    0.37p0.02          0.32p0.02
      have been shown consistently to be raised in pre-                 Basophils (109/l)
      eclampsia. However, in the present study there was no                 Ante-partum                           0.053p0.005*        0.037p0.004
      effect of parity on triacylglycerols or on total, LDL or              6 weeks post-partum                   0.055p0.004         0.051p0.005
      HDL cholesterol, either before or after delivery (Table               6 months post-partum                  0.060p0.009         0.050p0.006
         There were no differences in haemoglobin concen-
      tration or haematocrit between the groups (Table 4).              counts were still higher in the primigravid women, and
      There was no evidence that platelet consumption was               examination of lymphocyte counts before and after
      different between the groups, with platelet counts having         delivery using area under the curve showed the levels to
      similar values (Table 4). Three primigravida and three            be significantly higher in the primigravid women over
      multigravida had a platelet count of less than                    this time period (P 0.01) (Figure 3).
         Leucocyte counts were measured before and after                Effect of parity on biochemical markers of
      delivery, because they have been shown previously to be           endothelial dysfunction
      elevated in pre-eclampsia, and because of the potential for       The levels of the urinary metabolite of prostacyclin, 2,3-
      activated leucocytes to contribute to endothelial damage.         dinor-6-oxo-PGF α, were similar in the two groups
      Leucocyte counts were not different between the groups            before and after delivery. Similarly, levels of plasma
      at any time (Table 4). Neutrophil counts tended to be             endothelin 1 were not affected by parity either before or
      higher in primigravida before delivery, but not signifi-           after delivery (Table 3).
      cantly so (Table 4). There were, however, elevations of
      lymphocyte, monocyte and basophil counts in the                   Effect of parity on fetal outcome
      primigravid women relative to the multigravida before             Over 70 % of the women in both groups were delivered
      delivery (Table 4). At the post-partum visits, lymphocyte         by caesarean section. Gestation at delivery was similar

      # 1999 The Biochemical Society and the Medical Research Society
                                                                                                        Distinguishing features of primigravid pre-eclampsia   481

                                                                               multigravid than in primigravid women. Although the
                                                                               full time course of blood pressure change was not
                                                                               available for all the women we studied, in those who had
                                                                               attended outpatient clinics the average blood pressure
                                                                               between 22 and 28 weeks ’ gestation (prior to the onset of
                                                                               clinical symptoms) was not different between groups.
                                                                               Gleishner et al. [5] also noted that the higher blood
                                                                               pressure in multigravid women was associated with
                                                                               reduced fetal birthweight in this group compared with
                                                                               multigravid control subjects, and reasoned that this may
                                                                               represent a difference in pathophysiology. Our study
Figure 3 Comparison of lymphocyte count area under the                         contrasts with the results of Gleishner et al. [5], in that
curve for primigravid ($) and multigravid (
) women with                       birthweight did not differ according to parity and similar
pre-eclampsia                                                                  numbers of babies showed severe growth retardation
PP, post-partum. P   0.01 for comparison between primigravid and multigravid   independent of parity. The different findings may be
women.                                                                         explained in part by differences in subject selection. We
                                                                               studied severe cases of proteinuric pre-eclampsia that
                                                                               presented at around 30 weeks, whereas the report of
in primigravida (32.3p0.7 weeks) and multigravida                              Gleishner et al. [5] made no mention of proteinuria ; their
(32.0p0.6 weeks). The birthweights of infants born to                          patients had a later onset of hypertension, and the babies
primigravid women with pre-eclampsia averaged                                  were delivered later and were less growth-retarded.
1728p143 g, and this was similar to that of those born to                         At 6 months after delivery, SBP, although within the
multigravid mothers (1708p167 g). For the primigravid                          normal range, tended to be higher in primigravida
women, 65 % of babies had birthweights lower than the                          compared with the multigravid women. This finding
10th centile for gestation (indicative of growth retar-                        does not support previous studies suggesting that multi-
dation), compared with 64 % in the multigravid group.                          gravid women who get pre-eclampsia have underlying
                                                                               undiagnosed hypertension [4]. Increased systemic vas-
                                                                               cular resistance [16] and reduced aortic size [17] have
DISCUSSION                                                                     been described during pregnancy and up to 12 months
                                                                               post-partum in normotensive pregnant primigravida
This study examined clinical markers of pre-eclampsia                          compared with multigravida, without a difference in
and biochemical markers of endothelial dysfunction in                          blood pressure being observed. It is possible that these
women with proteinuric pre-eclampsia, seeking                                  changes are more pronounced in women that develop
differences according to parity that might suggest a                           hypertension, resulting in a relative elevation of blood
difference in pathophysiology.                                                 pressure in primigravida that persists, albeit to a lesser
  Although blood pressure recorded by resident staff on                        extent, for at least 6 months post-partum. An alternative
admission to hospital did not differ between primigravid                       explanation is that higher post-partum blood pressures
and multigravid women with pre-eclampsia, the entry                            may reflect higher normal blood pressure in this group
Dinamap SBP was 10 mmHg higher in primigravid                                  prior to pregnancy.
women than in their multigravid counterparts. This                                Nearly half of the multigravid women studied by us
difference was not explained by differences in gestation,                      reported that they had previously suffered pre-eclampsia.
which was similar in the two groups at the time of blood                       Only one subject reported having a different partner
pressure measurement, and occurred in spite of the                             from her last pregnancy, making it unlikely that altered
younger age of the primigravida. Indeed, the differences                       paternity was contributing significantly to pre-eclampsia
were independent of age, the presence or absence of anti-                      in the multigravid women. Multigravid women with
hypertensive therapy, the duration of anti-hypertensive                        recurrent pre-eclampsia had similar SBP values to multi-
medication, and smoking and alcohol consumption. In                            gravida who had pre-eclampsia for the first time, perhaps
primigravid women, there was a non-significant tendency                         suggesting that in this group a previous normotensive
for SBP to be elevated in subjects with a family history of                    pregnancy was no more protective in terms of developing
hypertension, but no such trend was seen in multigravid                        hypertension than a previous pregnancy associated with
women. Familial hypertension may possibly predispose                           pre-eclampsia.
women to develop pre-eclampsia in first pregnancies.                               A number of biochemical and haematological para-
  Our findings contrast with those of Gleishner et al. [5],                     meters used for clinical diagnosis were measured ante-
who found that blood pressure elevation occurred earlier                       partum. Although the levels of alkaline phosphatase were
in pregnancy in multigravid pre-eclampsia, and that                            higher than the normal range for this enzyme, there was
weight gain between this time and delivery was greater in                      no difference between primigravida and multigravida.

                                                                               # 1999 The Biochemical Society and the Medical Research Society
482   A. E. Barden and others

      However, aspartate aminotransferase was significantly              before delivery, with lymphocyte counts remaining
      elevated in primigravida before delivery, suggesting that         elevated for up to 6 months post-partum. The effect of
      these women had greater hepatic dysfunction. Plasma               parity on monocyte, basophil and lymphocyte counts
      creatinine and proteinuria were similar in the two groups,        appears to be specific to women with pre-eclampsia, as
      suggesting a similar level of renal impairment. Antenatal         we have not found such differences in primigravid
      platelet counts were similar in the two groups. Only              women who had normal pregnancies (results not shown).
      three women in each group had platelet counts of less             An inappropriate immune response to foreign antigens
      than 150i10*\litre, suggesting that platelet consumption          has been postulated as the cause of the pre-eclamptic
      was not a marked feature of pre-eclampsia in these                syndrome in primigravid subjects [6,25] ; however, evi-
      women. Haematocrit was similar in the two groups,                 dence to support this hypothesis is weak. One could
      suggesting that plasma volume was affected to a similar           speculate that if basophils, monocytes and lymphocytes
      extent in primigravida and multigravida. The levels of all        are activated to a different extent in primigravida, then
      these biochemical and haematological parameters were              higher counts of these cell types in primigravida may, in
      normalized post-partum and were not different between             part, explain the differences in severity. Whether the
      the groups, again suggesting that underlying disease was          changes in white cell count represent an inflammatory
      not present in the multigravida. Our study confirms                response to endothelial, placental or other organ damage
      observations in a group of 825 women with both mild               in pre-eclampsia, or indicate a more significant immune
      and severe pre-eclampsia who presented at a later stage of        disturbance affecting vascular and placental function,
      gestation, and in whom an increased incidence in primi-           remains to be determined. The difference in lymphocyte
      gravida of severe hypertension and liver disease was also         counts which persists for 6 months after delivery may be
      observed [18].                                                    due to an ongoing inflammatory response in primi-
         We were unable to find evidence for differences in              gravida, or may reflect an underlying immunological
      biochemical markers of endothelial dysfunction in re-             disturbance that existed in these women prior to preg-
      lation to parity, although the levels of 2,3-dinor-6-oxo-         nancy. Further studies are needed to confirm these
      PGF α were reduced in pre-eclampsia and levels of plasma          findings, and to clarify the role, if any, of lymphocytes,
      endothelin 1 were elevated compared with those in                 monocytes and basophils in the cause-and-effect chain of
      normotensive pregnant controls measured by us in                  pathophysiological changes in pre-eclamptic primi-
      previous studies [7]. Some studies have shown that lipid          gravida.
      metabolism is altered prior to the onset of clinical                 In conclusion, the elevated SBP and raised aspartate
      symptoms in women who develop pre-eclampsia [19,20],              aminotransferase activity observed in primigravida with
      suggesting that lipids may be important in the patho-             pre-eclampsia suggest a more severe form of the syn-
      physiology of the syndrome. Our study measured plasma             drome compared with that in multigravida. The lack of
      triacylglycerols and total, LDL and HDL cholesterol,              differences in birthweight and other biochemical and
      but found them to be unaffected by parity. The levels of          endothelial markers of severity of pre-eclampsia do not
      triacylglycerols in the women we studied were raised              suggest a different pathophysiology ; however, the per-
      compared with levels we have observed previously in               sistently higher white cell counts in the primigravid pre-
      normal pregnancy, similar to those of proteinuric pre-            eclamptics are of interest, and may reflect differences in
      eclamptics studied previously by us [12,21]. This con-            immune responses between the two groups. We suggest
      trasts with the study of Deslypere et al. [22] in normal          that studies investigating the pathophysiology of pre-
      pregnant women studied within 48 h of delivery, who               eclampsia should include multipara as long as there is
      reported that triacylglycerol and LDL levels were                 adequate post-partum follow-up to exclude underlying
      increased in multipara. Differences in body mass index            disease.
      between the parous groups in the two studies might
      account for these discrepancies.
         Although leucocytes are not assessed in the clinical
      diagnosis of pre-eclampsia, they may be important in the
      pathophysiology of the disease because of their ability to        ACKNOWLEDGMENTS
      contribute to endothelial dysfunction when activated by
      released cytokines or cytotoxic substances. A number of           This study was supported by a National Health and
      studies in women with pre-eclampsia have shown that               Medical Research Council Program Grant, and a grant
      neutrophils are activated compared with normal preg-              from the National Heart Foundation of Australia. We
      nancy [11,23,24], raising the possibility that they may           acknowledge Mrs. Natasha Morton for her technical
      contribute to endothelial dysfunction. In the present             assistance, Dr. Valerie Burke for her advice on statistical
      study, marked elevations in monocyte, basophil and                analysis, and the obstetric and nursing staff at King
      lymphocyte counts were observed in the pre-eclamptic              Edward Memorial Hospital for Women for their help in
      primigravid women compared with the multigravida                  patient recruitment.

      # 1999 The Biochemical Society and the Medical Research Society
                                                                                              Distinguishing features of primigravid pre-eclampsia   483

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                                                                    Received 18 November 1999/17 May 1999; accepted 8 July 1999

                                                                  # 1999 The Biochemical Society and the Medical Research Society