The longitudinal relationship between prenatal maternal cortisol and preschool internalising problems

Intro: Prenatal exposure to synthetic glucocorticoids may increase the risk of emotional symptoms in childhood partly by reducing fetal growth. We explored if physiological levels of prenatal maternal cortisol were associated with internalising problems in boys and girls and if this was mediated by birth weight. Methods: Mother-child dyads from the prospective Odense Child Cohort (n=1162) were included if maternal serum cortisol (3rd trimester), offspring birth weight, and Child Behaviour Checklist (CBCL) assessments in preschool age were available. Crude and adjusted associations between cortisol and internalising problems were determined in linear mixed models stratified by offspring sex. Covariates included parental psychiatric history, parity, maternal age, education, smoking during pregnancy, and gestational age at birth. In the presence of significant associations, we evaluated the potential mediating role of birth weight. Results: The study sample included 601 boys and 561 girls and internalising problems were assessed at mean ages 2.3 (±0.4) and 5 (±0.5) years. In the crude analysis, cortisol was positively associated with internalising problems in boys (p-value 0.017) and in girls (p-value < 0.0001). In the adjusted analyses, there was no statistically significant association between cortisol and offspring internalising problems in boys or girls (all p-values > 0.15). There was no mediation by birth weight. Discussion: Maternal serum cortisol was positively associated with offspring internalising problems in boys and girls, but there was no association following adjustment for potential confounders and no mediation through birth weight. Maternal third-trimester cortisol levels do not predict preschool offspring internalising problems in our study.