Negative Temperamental Reactivity in Infancy and Toddlerhood: Are They Related to Maternal Depression and Anxiety in Pregnancy? Background Alterations of neurodevelopment underlying behavioral problems and psychopathology have been shown to have their origins in prenatal life. We prospectively studied the relationship between maternal anxiety and depression during pregnancy and individual differences in negative reactivity during infancy and toddlerhood. Methods In a prospective-longitudinal study, maternal anxiety was measured at 5-14, 15-27 and 28-40 weeks of pregnancy with the State Trait Anxiety Inventory (STAI), Pregnancy Anxiety Questionnaire (PRAQ-R) and Edinburgh Depression Inventory (EDI), in 155 pregnant women. Infant negative reactivity was measured at 4-8 months with the Infant Behavior Questionnaire-Revised (IBQ-R) and at 30-36 months with the Early Childhood Behaviour Questionnaire. Data were analysed with hierarchical regression analyses (SPSS 17.0). Parity, maternal educational level and postnatal maternal state anxiety, birth weight and sex of the baby were added as covariates if they were significantly correlated with infant reactivity. Results State anxiety in first trimester (STAI; Mean=35.96; SD=9.92) was significantly associated with offspring negative reactivity; it explained 8 % of the variance at 4-8 months (IBQ-R; F (2, 102) = 5.95; p = .004) and 6.5 % of the variance at 30-36 months (ECBQ; F (2, 125) = 7.23; p = .001). Of specific pregnancy related anxieties (PRAQ-R), only third trimester fear for changes was significantly associated with infant reactivity at 4-8 months, explaining 7 % of the variance (IBQ-R; F (2,102)=7.151; p= .001). Postnatal maternal anxiety was in all analyses significantly associated with infant reactivity, but it did not account for the influence of prenatal anxiety. Discussion Our results provide evidence for an association between maternal anxiety during pregnancy and negative reactivity in infancy and toddlerhood that is independent of key sociodemographic and obstetric factors and concurrent postnatal maternal anxiety.