Foetal exposure to maternal depression predicts cortisol responses in infants: findings from rural South India

Background Maternal depression during pregnancy is associated with an increased risk of adverse child outcomes. One potential mechanism is the influence of antenatal depression on the foetal hypothalamic‐pituitary‐adrenal axis. This can be observed as disturbances in baseline cortisol secretion during childhood. The influence of antenatal depression on infant cortisol reactivity to a stressor may provide further insight into this association. In addition, the dose–response relationship between foetal exposure to antenatal depression and infant cortisol reactivity is unclear. Methods A consecutive sample of 133 pregnant women in their third trimester was recruited from an antenatal clinic in Karnataka, South India. Women were assessed for depression before and after birth on the Edinburgh Postnatal Depression Scale (EPDS) and the Kessler 10 Scale. Salivary cortisol response to immunization was measured in 58 infants at 2 months of age. We aimed (i) to investigate the association between antenatal depression and infant cortisol reactivity to immunization and (ii) to explore whether the relationship is dose‐dependent. Results Exposure to antenatal depression independently predicted elevated infant cortisol responses to immunization (β = 0.53, P = 0.04). The association was found to be U‐shaped, for antenatal depression measured on the EPDS, with the infants exposed to the highest and lowest levels of maternal antenatal EPDS scores during intra‐uterine life showing elevated cortisol responses to immunization (R2 = 0.20, P = 0.02). Infants exposed to moderate levels of maternal antenatal depression showed the lowest cortisol response to immunization. Conclusions These findings suggest that the association between antenatal depression and infant cortisol reactivity is dose‐dependent and U‐shaped, implying that infants exposed to both low and high levels of maternal depression showed greater reactivity. The study provides the first evidence of such an association from a low‐income setting.