Background:This exploratory study investigates the influence of maternal cortisol and emotional state during pregnancy on fetal intra-uterine growth (IUG). We expected higher basal cortisol levels, or more depressive and anxious complaints during pregnancy, to be associated with slower IUG and lower birth weight.Methods:91 pregnant women were recruited from the antenatal clinic and were seen once each trimester. Next to psychological assessments, a diurnal cortisol profile was derived from saliva samples. IUG was evaluated using ultrasound.Results:In mid-pregnancy (T2) basal cortisol levels significantly predicted the variance of weight (Proportion of variance in growth variable explained (PVE)=11.6%) and body mass index (BMI) at birth (PVE=6.8%). In late-pregnancy (T3) emotional state, particularly depressive symptoms (BMI at Birth: PVE=6.9%; Ponderal Index (PI) at birth: PVE=8.2%; head circumference at T3: PVE=10.3%; head circumference at birth PVE=9.1%) and attachment (BMI at Birth: PVE=6.9%; PI at birth: PVE=7.2%) had an influence on growth.Analysis of growth between T2 and T3 showed that attachment and cortisol in T3 had an influence on the variation in increase in estimated fetal weight (PVE=12.5% - PVE=8.6%).Conclusion:These data indicate basal cortisol levels were more important in T2. Whereas emotional state was more important in T3.