BACKGROUND: Maternal symptoms of depression constitute an early adversity for infants that is considered to exert its effects via the maternal-placental-fetal neuroendocrine axis. Previous research implicates associations between maternal prenatal symptoms of depression and infants' glucocorticoid (GC) levels shortly after birth. To date, associations have not been investigated in the early postnatal period. The current study aimed to investigate the influence of maternal perinatal symptoms of depression on infants' neonatal and postnatal hair GCs providing a retrospective reflection of integrated cortisol secretion in the intrauterine and early postnatal period, respectively.

METHODS: As part of a prospective cohort study, hair samples of infants were taken up to two weeks after delivery (N = 152) and again eight weeks after delivery (N = 165). Liquid chromatography-tandem mass spectrometry was used to determine hair cortisol and cortisone in scalp-near 2-cm hair segments. Maternal symptoms of depression were assessed during pregnancy and eight weeks postnatally based on the Edinburgh Postnatal Depression Scale.

RESULTS: Higher maternal prenatal symptoms of depression showed a significant association with higher infants' neonatal hair cortisol, when controlling for confounding variables (i.e., gestational age, mode of delivery, parity, storage time, pregnancy complications). A non-significant trend for this effect was found for the hair cortisol-to-cortisone ratio while no effect occurred for hair cortisone. No association of maternal postnatal symptoms of depression with infants' postnatal hair GCs was observed. Further exploratory analyses revealed no relationship between a change of maternal prenatal to postnatal symptoms of depression with the change from infants' neonatal to postnatal hair GC levels or postnatal hair GCs.

CONCLUSION: Our results suggest that maternal prenatal symptoms of depression are associated with dysregulated infants' hair cortisol levels mainly incorporated in the intrauterine period which, in turn, might contribute to increased susceptibility for later diseases. However, no relationship was observed in infants' hair samples additionally reflecting hair GCs of the early postnatal period. Future studies should consider research on associations between maternal symptoms of depression and infants' hair GCs also later in life and take into account additional risk factors with potential impacts on GC secretion during early infancy.