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WHAT EVERY EVERY WOMAN WOMAN SHOULD SHOULD KNOW KNOW

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WHAT EVERY EVERY WOMAN WOMAN SHOULD SHOULD KNOW KNOW

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									       THE DANGERS AND RISKS

                OF

        PRENATAL DIAGNOSIS




WHAT
       EVERY
            WOMAN
                  SHOULD
                           KNOW



                 1
AT THE BEGINNING OF PREGNANCY:

When a woman first realizes that she may be pregnant she begins to think about the
wellbeing of the child she is now carrying. She will become very careful about what
she does, where she goes, and what she eats. As she plans to protect and provide for
her new son or daughter, she is taking the first steps on the path of motherhood,
welcoming the growth of new life; discerning what is safe from what is unsafe.

In seeking to promote health and security for the new person entrusted to her care, she
will visit doctors and perhaps midwives and other health care professionals from early
in her pregnancy. The first visit to a doctor will usually confirm the pregnancy, and
plan future antenatal care. Good antenatal care includes various checks and
investigations at different stages in the pregnancy. It will include tests that are designed
to safeguard the well being of mother and baby. In other words, these tests are
performed in the hope of some therapeutic benefit. Good antenatal care will never
jeopardize the health of the mother or her unborn child unnecessarily. Its purpose is to
place this baby in his or her mother’s arms at the end of pregnancy with both enjoying
the best possible health.

Prenatal screening and diagnostic programs, however, represent a different goal
achieved by a differing set of standards. They focus on different outcomes, too, and are
considered successful when they have identified certain babies with abnormalities. The
conditions mainly looked for in these programs are not those that can be treated and
made good. As such, the progressive steps on the prenatal screening to diagnosis
pathway do not follow the normal principals of medical screening programs. They are
not simple, inexpensive and safe investigations for treatable problems. Prenatal
diagnostic tests will directly cause the death of some babies, both accidentally because
of complications, as well as intentionally, because parents may accept the offer of
abortion that is made in the time of distress after their baby has a positive test result.

WHAT TESTS CAN HELP MOTHER AND BABY?

Even at this first visit some standard tests may be organised. These require a blood
sample from the mother so that anaemia can be looked for, her blood group recorded as
well as the presence of any antibodies, and her level of immunity to Rubella (German
measles) checked. Some infections, which might require treatment during pregnancy or
soon after the birth, will also be looked for. There are other blood tests which may be
thought necessary after the doctor has talked with the mother and examined her. A
urine sample is also collected at this time and a Pap smear may be done. Although not
routinely performed in these early weeks, an ultrasound may be recommended to make
sure of the date when baby is due to be born or to check that the baby is growing
within the womb and is not in an ectopic location, i.e. outside the uterus.

                                             2
At about the eighteenth week of the pregnancy women are usually asked to have an
ultrasound scan which can then produce a much more detailed image of the baby and
baby’s organs than was possible earlier in the pregnancy. This will reveal the size and
so suggest the age of the baby, as well as looking at his or her development. The
position of the placenta will be seen, and its lower edge defined. It is now that the
mother usually learns if she is carrying twins.

Sometimes, if abnormalities are detected on this ultrasound scan, the timing place and
manner of delivery can be adjusted to provide the best outcome for the baby and the
mother.

Ultrasound carries no known risk to the baby. It uses high frequency sound waves
which are reflected back to create an image of the foetus. Follow up ultrasounds may
be advised later on to re-check or to monitor progress in these areas. There are special
maternity hospitals and other centres which offer tertiary level referral for more
detailed ultrasound assessment of the baby if some abnormality has been suggested on
a previous scan. These tertiary ultrasound services exist in all States within foetal
medicine units, where radiologists and obstetricians have special interest in this field.

WHAT OTHER TESTS MIGHT BE SUGGESTED AT THIS TIME?

Scientific advances in the last few years have made it possible to do prenatal screening
for other abnormalities known as “birth defects”. These include chromosomal
abnormalities (where the structure or number of chromosomes in each cell is altered
e.g. Down syndrome), genetic abnormalities (where a gene on the chromosome may be
altered or missing e.g. Cystic Fibrosis), and anatomic or structural problems such as
neural tube defects where the brain may be affected (anencephaly) or in the spine
(spina bifida). After screening test results are known, some mothers will be advised to
undergo further diagnostic testing, known as invasive tests, to make the diagnosis
certain.

Curative treatment is not available for these conditions, chromosomal and genetic
abnormalities. Ultimately the purpose of such screening is to select out affected babies
for abortion. As the number of tests available to pick up birth defects increases, so does
the number of couples offered these tests.

HOW IS PRENATAL SCREENING DONE?

Current tests for prenatal screening are:
  • An ultrasound scan of the foetus for nuchal translucency measurement.
  • The “combined test” of both nuchal translucency and maternal serum screening.
  • Second trimester maternal serum screening.

                                            3
It is very important to understand what each of these tests means:-

The Ultrasound for Nuchal Translucency measures the thickness of the fluid filled
space under the skin at the back of the baby’s neck. This tissue is only seen and
measurable when the baby is a certain size which occurs between 11 weeks and one
day and 13 weeks and 6 days, from the beginning of the mothers last menstrual period,
(this interval is known as the gestation). The thicker the nuchal lucency the greater the
chance the baby has the chromosomal abnormality Down Syndrome (trisomy 21).
Increased width can also be associated with other trisomies as well as structural heart
problems. Testing should only be done by specialists with a high level of skill and
training who are duly accredited.

How accurate is it? The test has a significant false positive rate, and false negative
rate; not detecting 20% to 30% Down Syndrome babies. Screening tests identify babies
at risk of abnormality. Diagnostic (“invasive”) tests identify which of these babies
have an abnormality. Mothers of these babies are offered an abortion.

The Combined test: This prenatal screening test makes use of two blood results from
the mother combined with the nuchal translucency scan. The maternal blood (maternal
serum screening or MSS) component is also timed in relation to the age of the baby,
and is usually collected from the mother at 10 weeks to 13 weeks gestation. It
measures the levels of two substances. One is the hormone B-hCG which is known to
be present in greater amounts in the bloodstream of mothers who are carrying Down
syndrome babies. The other substance measured from this same sample of blood is an
enzyme called PAPP-A. It is known to be present in lower amounts in the bloodstream
of mothers who are carrying Down Syndrome babies. Levels of this enzyme in the
mother’s blood can also be affected by other factors such as her weight.

 Very accurate information, including all this data (the mother’s weight, the exact
gestational age of the baby etc.) needs to be supplied to the pathologist when the blood
is collected, or the end result will be less accurate.

Background data, nuchal translucency measurements and maternal serum screening are
then combined to perform a calculation using a specific software programme. Different
mathematical weighting is given to each of the components entered into this
calculation. Special calculations are needed in the case of twin pregnancy. A result is
then usually given to the mother by her family doctor or obstetrician. It is, in the end, a
risk assessment only. The parents will be told their approximate risk of having a baby
with Trisomy 21 i.e. a normal risk or an increased risk. Other chromosomal
abnormalities may be suggested by this screening test.


                                             4
HOW RELIABLE IS THE COMBINED SCREENING TEST?

The combination of nuchal translucency and a maternal serum screening give more
information to assess the risk of Down syndrome than either test alone. That is why
mothers of all ages may be encouraged by health professionals to have this test done,
on the grounds that it is not invasive and does not harm the baby. Older mothers do
have more chance of having Down syndrome babies, so they may find that health
personnel consider this screening to be almost a routine test or “best medical practice”.
However, understanding the reliability of this test is not straight forward: The false
positive rate for this test (the percentage of women who are designated higher “risk”
but are carrying perfectly normal babies) is usually said to be 5%. This figure has been
calculated across all age groups. The risk calculation formula is heavily weighted
though, by the mother’s age. If for example, a 44 year old woman agrees to have the
combined test done, there will be 47% false positive rate. That is, for every one
hundred 44 year old women having nuchal translucency and maternal serum screening
–which they would definitely be encouraged to have – 51 of them will be told the
results suggest the high risk category for Down syndrome. They will be recommended
invasive diagnostic testing to analyse baby’s chromosomes (called karyotyping). Of
these 51 mothers about 5 will have an affected baby. To look at it another way a
mother of 44 may have the same translucency measurement and the maternal serum
screening biochemistry as a younger woman but be assigned to a high risk category
because of the weighting of her age in the equation.

Over all, at least one in ten babies with Down syndrome will not be picked up by this
screening test – this is a false negative rate.

Second Trimester Maternal Serum Screening:
This maternal blood test has largely been replaced by first trimester screening for
chromosomal abnormalities. Like other screening tests it is time dependent, and the
mothers blood must be collected between fifteen and seventeen weeks gestation. It too,
looks for Down syndrome, as well as trisomy 18 (another chromosomal abnormality)
and spina bifida and anencephaly. It too, will assign a “risk” or seek to estimate the
likelihood of such an abnormality.

This estimate is arrived at by measuring substances produced by the baby and the
placenta, which are present in the mother’s blood. These results are put together with
the mother’s age and weight and ethnic background; and the baby’s gestational age to
produce this “risk” assessment. The test will pick up 65% to 70% of Down Syndrome
babies. Like all screening tests, however, it also produces errors. One in twenty
mothers who have this test will be told they have an increased risk, but most of these
babies are in fact normal. Therefore, if the level of risk is increased, it will be
suggested to the mother that a more accurate diagnostic test - amniocentesis- be
performed.
                                            5
Where Do These Screening Tests Lead?
There is much heightened anxiety surrounding these tests at what should be a time of
great rejoicing for the gift of new life. Instead, according to the reasoning behind the
whole screening process, many mothers undergo further, more dangerous tests with
significant complications and mortality rates.

While these screening tests do not of themselves pose a threat to the baby, an abnormal
result, a designation of increased risk, creates a climate of uncertainty and anxiety for
the parents. A mother who would not normally consider an abortion will now find
health professionals suggesting more invasive tests to make certain of a diagnosis that
her baby probably does not have, and for which there is no treatment.

Coping with society’s expectations of a perfect baby, and sometimes that of friends
and family, can place pressure on the parents to conform to modern ways of dealing
with imperfect babies. Foetal medicine has many successes and achievements but it
can offer nothing more at this point except to begin invasive testing that might of itself
kill the child, even before diagnosis is known. It is a sad reality that all these tests, both
screening and diagnostic - the end product of much scientific endeavour and research
investment - are part of a recommended protocol to select and kill imperfect babies.

In Australia today abortion is considered best practice for the abnormalities these
screening tests are designed to reveal

No treatment at this time can repair or cure the chromosomal or genetic alterations, the
spinal or brain abnormalities that we are looking for.

INVASIVE DIAGNOSTIC PROCEDURES IN THE FIRST HALF OF
PREGNANCY:

In what circumstances are these tests suggested?
   • if the mother is over 35 years, this test may be offered in some situations
   • If one of the prenatal screening tests mentioned above ( nuchal lucency, the
     combined test, MSS) has estimated that the baby has an increased chance of
     having an abnormality.
   • If the routine 18 week ultrasound has picked up an abnormality.
   • If the couple have had a previous child affected by a chromosomal or other
     inherited disorder for which tests have been developed.
   • If there is a family history in either parent of certain inherited disorders. Genetic
     counselling is usually recommended for such couples before conception takes
     place.


                                              6
WHAT ARE THEY?
These tests obtain cells from the baby or the placenta and these are grown in the
laboratory. The collection of these cells for prenatal diagnosis is performed either
through chorionic villus sampling or amniocentesis. A third test known as
cordocentesis is very rarely done but may also be suggested to clarify a diagnosis,
biochemical tests may also be performed on the sample collected.

Chorionic Villus Sampling (CVS):
This test is performed early in the pregnancy, usually from 10 to 12 weeks (preferably
after 10 weeks to reduce the risk of limb damage to the baby). A needle is passed
through the mother’s abdomen under ultrasound guidance and through the uterus, to
part of the forming placenta. The cells that are in this tissue usually contain the same
chromosomes as the baby. A part of it, known as the chorionic villi (little frond-like
strands), is then sampled and drawn back up the syringe. About ten to fourteen days
later the results of culturing these cells for karyotyping i.e., chromosomal analysis, will
be known. Within this time gene test results will also become available. Chorionic
villus sampling may be performed through the vagina but this is now uncommon in
Australia

This diagnostic test will directly cause the death of some children. They will either die
within the next few weeks (miscarriage) or even sometimes months later. The
miscarriage rate quoted by the doctor will vary according to the skill of the operator or
unit. Some studies show that CVS now kills 1in 200 babies tested, some other sources
suggest 1 in 100 babies will be killed by this procedure. Also as a direct effect of
trauma, baby’s arms legs and fingers may be deformed, particularly if the test is done
earlier than 10 weeks gestation. Both mother and child can also develop an infection
from this test.

One percent of test results will be inconclusive. Normal chromosomes may grow in
one cell culture and abnormal chromosomes in another. This is called “mosaicism” and
when it occurs further invasive testing may then be offered.

As a method of diagnosis, CVS is sometimes performed because results can be known
at 12 or 13 weeks gestation and an abortion carried out before the mother is visibly
seen to be pregnant. There is less chance of an abortion causing sickness and death in
the mother now, than if an abortion is carried out later

Amniocentesis:
This test is performed later in the pregnancy usually between 15 and 17 weeks
gestation. Under ultrasound guidance, a needle is passed through the mother’s
abdomen, through the uterine wall, through the membrane, and into the amniotic sac.
                                             7
About 15mls of amniotic fluid is then drawn up. Amniotic fluid is water within the
amniotic sac which surrounds the baby. This fluid is made by the baby’s kidneys, and
contains cells from the skin, urinary tract and lungs dispersed through it, as well as
other substances.

One such substance which can be measured is alpha- fetoprotein. High levels of this
foetal protein are produced when there is a defect in the closure of the spinal cord,
called a neural tube defect (NTD), more commonly known as spina bifida. However,
higher than normal levels have been found in other conditions such as, incomplete
closure of the abdominal wall, renal conditions, foetal teratoma, threatened miscarriage
and twins. Most neural tube defects are diagnosed on ultrasound these days.

Amniocentesis is mostly done to detect chromosomal abnormalities (such as Down
Syndrome). Cells from the amniotic fluid are grown and developed in cultures and
chromosome analysis can then be done, with the results known in 10 to 14 days. A
more rapid technique known as FISH (Fluorescent In Situ Hybridization) can give
some chromosomal results in 48 hours. Specific gene abnormalities can also be
analysed from this collection.

Like all invasive testing, amniocentesis can be fatal for the baby, and will kill up to
approximately 1in 200 babies tested. Some current obstetric resource texts quote one in
every hundred babies tested will miscarry. Those advocating amniocentesis will tend to
quote statistics more reassuring to the mother. There is a higher risk of miscarriage if
the test is done before 14 weeks gestation. It has also been reported that respiratory
distress and abnormalities in posture may occur later when there has been chronic
amniotic fluid leakage following this investigation.

The baby may be 18 weeks gestation or more when the complete karyotyping results
are finalized and a diagnosis of Down Syndrome or other abnormality is known. A
mere five to six weeks before viability (the earliest age at which babies can be born
and still survive), the mother is then offered an abortion. At the time of the abortion A
FEW of these babies will be born alive and die shortly afterwards with breathing
difficulties (most will be born dead).

Cordocentesis:
This test is rarely performed, but may be suggested to clarify a diagnosis in doubt, such
as is caused by the effects of mosaicism in cell culture lines: Under ultrasound
guidance a needle is passed into the umbilical cord to draw a sample of baby’s blood.
One in fifty babies will die from this procedure to determine its chromosomes.




                                            8
I HAVE HEARD OF COUPLES SELECTING THEIR CHILDREN - WHAT DOES
THAT MEAN?
This is Pre -implantation Genetic Diagnosis (PGD)
This is a relatively new development in the field of prenatal diagnosis and it is
available exclusively within the IVF (in vitro fertilisation) services of private
industries. It involves biopsying an embryo that is three to five days old. This method
has been used to select the gender of the baby.

At this stage of a baby’s development, three or five days after conception, it normally
would be passing down the fallopian tube of the mother towards the womb to nestle or
implant there and continue its growth. The babies tested in pre-implantation genetic
diagnosis have only ever existed in the laboratory. They have been formed using
Assisted Reproductive Technology (ART).

Under this technology a woman is given hormones to stimulate her ovaries to produce
an excessive number of eggs. These eggs are then surgically removed from the woman
and fertilized with sperm “in vitro” which means literally “ in glass” i.e. in a glass
receptacle in the laboratory. Each baby formed by this procedure will then begin to
grow by normal cell division. When he or she is three days old the embryo will contain
about eight cells. One of these cells is then removed and biopsied from each eight cell
baby formed from the couples eggs and sperm. Each of the cells biopsied contain all
the genetic information of that individual; its sex, physical characteristics, and also its
imperfections. It can then be tested for errors within a specific gene (e.g. looking for
cystic fibrosis) or for abnormal DNA patterns within a region of a chromosome. The
sex will be determined, which is relevant in some sex chromosome linked disorders
(such as haemaphilia and Duchene muscular dystrophy) so that the technician can
ascertain which male children are affected, which female children are carriers of the
disorder and which children do not have the gene in question at all. The technician can
also identify certain chromosomal abnormalities at this time using the rapid FISH
technique mentioned above.

Babies which are shown not to be affected by the abnormalities for which they are
tested are then transferred into the mother’s uterus, or frozen for possible use later.
Those babies who appear to have the defective genes or chromosomes tested for, and
those babies who are found to have a disorder as well as most carriers are discarded.
Like other prenatal tests, PGD is imperfect with false positives and false negatives
noted. It is promoted by private industry, obstetricians and many geneticists, genetics
educators and counsellors as a test “for couples with a moral or religious objection to
pregnancy termination.” (‘PRENATAL TESTING’ The centre for genetic education April 2004)
Obstetric text books list PGD’s advantage as providing a diagnosis ‘pre-pregnancy,
reducing the need for pregnancy termination’. (Oxford Handbook of Obstetrics and
Gynaecology)


                                             9
These claims are false. Their misleading assurances are derived from new definitions
of pregnancy as commencing only when the baby implants in the womb, when it is
approximately 5 or 6 days old. That is, a pregnancy is said to begin on day 5 or day 6
of the pregnancy. This is at odds with the science of embryology and the teaching of
the Church. It is convenient, however, for the IVF industry, and for the marketing of
abortifacient (causing an abortion) pharmaceuticals and devices which are promoted as
contraceptives. This re-defining of pregnancy which international organisations (FIGO
the Federation of Gynaecologists and Obstetricians) first initiated, is rarely explained
to mothers making these decisions.

FUTURE DEVELOPMENTS

As DNA technology advances, current prenatal screening tests and diagnostic tests
may change. Baby’s nucleated cells (the nucleus contains the chromosomes) can be
found in the mothers’ blood stream and in the cervix. These cells can now
experimentally be collected on blood tests and Pap smears, separated from the
mother’s cells and examined for genetic and chromosomal anomalies. It has been said
that such tests will change ante-natal care by being offered to all mothers regardless of
their age and level of risk, hence all babies would potentially be screened for
untreatable conditions for which abortion is considered best practice between 6 and 20
weeks gestation.

At present the Pap method of cell collection is proposed only as a screening tool,
which, it is envisaged could be released in the next 12 months. Positive results would
still need to be followed by amniocentesis and chromosome analysis; although
experimenters are claiming high levels of accuracy. Insufficient Pap smear sample
numbers have been studied to validate the reliability of this test. A maternal blood test
has also been researched to pick up the baby’s DNA in her blood stream , to determine
foetal chromosomal numbers. it still needs to be followed up with an invasive
diagnostic test, because it is not sufficiently accurate. (Lancet, 2007)

After 20 weeks gestation there are medical conditions which require investigations for
therapy for mother and baby, such as amniocentesis in the case of some blood
disorders. These are in no way to be confused with the screening programme of the
first half of pregnancy. Almost all investigations later in the pregnancy are to help the
baby live and grow to its full potential. The prenatal diagnosis outlined in one NSW
Health Department pamphlet “The Importance of Checking Your Baby’s Health before
Birth” reflects the importance assigned to ensuring abnormal babies will not be born.




                                           10
This document was written and compiled by Dr Deirdre Little M.B.B.S.,
D.R.A.N.Z.C.O.G., F.A.C.R R.M, with assistance from members of the Catholic
Women’s League of the Lismore Diocese. Dr Little is a GP obstetrician involved in
antenatal and intrapartum care in Bellingen NSW and is a member of the Bellingen
Branch of the Catholic Women’s League.




Bibliography:
   • Royal Australian and New Zealand College of Obstetrics and Gynaecology (RANZCOG)
Guides for parents
           1. Why Aren’t All Babies Perfect? Ed.2004
           2. Prenatal Screening for Down Syndrome and Other Chromosomal Conditions
              Ed.2 2006
           3. Amniocentesis and Chorionic Villus Sampling Ed. 3 2006
           4. Antenatal Care and Routine Tests During Pregnancy Ed 2 2004
   • Pre-Conception Health Care
       Australian Doctor 18 June 2004
   • “Sullivan Nicholaides Pathology” Patient handout “Pre-natal Testing for Down Syndrome
       and Other Abnormalities. The Role of Pathology Testing.
   • ‘Advances in Pre-natal Screening” Andrew McLennan Australian Family Physician Vol 32
       no.3 March 2003
   • “Screening for Down Syndrome” Dr Bruce Campbell
   • Sullivan Nicolaides Pathology “First trimester screening for Down Syndrome”
   • The Importance of Checking Your Baby’s Health Before Birth NSW Dept of Health
   • Prenatal Tests- Special tests for you r Baby – Centre for Genetic Education April 2004
   • Pre-implantation Genetic Diagnosis – Sydney IVF
   • The Oxford Handbook of Obstetrics and Gynaecology 2004
   • Lancet 2007, Pages 369,474 -81
 Support Groups
Pregnancy Help
The Association of Spina Bifida and Hydrocephalus
The Down Syndrome Association (NSW)




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