Relation between maternal antenatal anxiety and infants' weight depends on infants' sex: A longitudinal study from late gestation to 1-month post birth

Objective: To test for gender-differences in the relation between mothers' antenatal anxiety and infants' body weight during gestation, at birth, and at 1-month of age. Methods: Two hundred and twelve randomly-recruited women were divided into two groups: Controls (n = 105) and Anxious Group (n = 107) based on a standard cut-off of the Beck Anxiety Inventory. Outcome measures were Fetal Weight derived from biometrics obtained from an ultrasound scan in the 3rd trimester and infants' weight at birth and at 1-month of age, both obtained from medical records. Results: Multivariate analyses showed main effects of Gender on infants' birth weight (P = .001) and on infants' weight at 1-month of age (P = .004), but no main effects of Anxiety Group at any time-point. Gender x Anxiety Group interactions at all three time points (Fetal weight: P = .05; Birth weight: P = .03; 1-month of age: P = .10) reflected gender differences (males > females) among infants in the anxious group, but not among controls. Distinct trends regarding same sex comparisons across groups (Control vs. Anxiety) were in line with predictions (male controls < male anxious; female controls > females anxious). Controlling for Postpartum Anxiety and Antenatal and Postpartum Depression in the models did not affect primary results. Conclusion: Gender differences in fetal and birth weight were more substantial among infants of anxious mothers than among controls due to the seemingly accelerated growth of "anxious" males and the diminution of weight among "anxious" females.