Foetal programming and cortisol secretion in early childhood: A meta-analysis of different programming variables.

It is widely recognized that different events may take place in the intrauterine environment that may influence later developmental outcome. Scholars have long postulated that maternal prenatal stress, alcohol or drug use, and cigarette smoking may impact foetal formation of the hypothalamus-pituitary-adrenal (HPA) axis, which may later influence different aspects of early childhood socioemotional and cognitive development. However, results linking each of these factors with child cortisol secretion have been mixed. The current meta-analysis examined the relation between each of these programming variables and child cortisol secretion in studies conducted up to December 31st, 2012. Studies were included if they were conducted prior to child age 60 months, and if they reported an index of effect size linking either maternal prenatal stress, alcohol or drug use, or cigarette smoking with an index of child cortisol secretion. In total, 19 studies (N=2260) revealed an average effect size of d=.36 (p<.001). Moderator analyses revealed that greater effect sizes could be traced to maternal alcohol use, to the use of retrospective research methodology, where mothers are questioned after childbirth regarding programming variables, and to the use of baseline measures of cortisol secretion, as opposed to recovery measures. Discussion focuses on processes that link the environment to foetal development and how both are linked to later adaptation.