Antenatal maternal psychological distress may be associated with reduced placental circulation, which could lead to lower birthweight. Studies investigating this in humans show mixed results, which may be partially due to type, strength and timing of distress. In addition, the arterial vascular resistance measures often used as outcome measures do not detect smaller changes in placental volume blood flow. We aimed to investigate the effect of a specific stressor, with increased levels of stress early in pregnancy, on the fetoplacental volume blood flow in third trimester.
This was a prospective observational study of 74 pregnant women with a congenital malformation in a previous fetus or child. Psychological distress was assessed twice, around 16 and 30 weeks' gestation. Psychometric measures were the General Health Questionnaire-28 (subscales anxiety and depression), Edinburgh Postnatal Depression Scale, and Impact of Event Scale-22 (subscales intrusion, avoidance, and arousal). Placental circulation was examined at 30 weeks, using Doppler ultrasonography, primarily as fetoplacental volume blood flow in the umbilical vein, normalized for abdominal circumference; secondarily as vascular resistance measures, obtained from the umbilical and the uterine arteries.
Maternal distress in second but not third trimester was associated with increased normalized fetoplacental blood flow (P-values 0.006 and 0.013 for score > mean for depression and intrusion, respectively). Post-hoc explorations suggested that a reduced birthweight/placental weight ratio may mediate this association. Psychological distress did not affect vascular resistance measures in the umbilical and uterine arteries, regardless of adjustment for confounders.
In pregnant women with a previous fetus or child with a congenital malformation, higher distress levels in second trimester were associated with third trimester fetoplacental blood flow that was higher than expected for the size of the fetus. The results do not support placental blood flow reduction as a pathway between maternal distress and reduced birthweight.