The effects of prenatal social stress on behaviour: mechanisms and function

In this review, we summarise experimental animal studies on the effects of the social environment during pregnancy on the offsprings' behaviour, brain, and neuroendocrine function. We show that in non-human mammals the stability of the social environment in which the pregnant females live is critical for the offsprings' social and sexual behaviour later in life as well as for reproductive functioning, endocrine state and androgen and estrogen receptor distribution in specific parts of the brain. Based on these findings, we discuss different neuroendocrine mechanisms mediating the influence of the social environment during pregnancy on the offsprings' behaviour. We conclude that maternal steroids play a decisive role in shaping foetal brain development. However, a pituitary adrenocortical pathway need not always be involved. At least in some cases an involvement of the sympathetic adrenomedullary system seems to be possible. Concerning function, we favour the hypothesis that the behavioural effects of prenatal social stress are not necessarily the 'pathological' consequences of adverse social conditions (non-adaptive explanation). Contrarily, mothers could be adjusting their offspring to the environment in which they live during pregnancy in an efficient way (adaptive explanation).