Numerous studies have shown that prenatal stress (PNS) can have profound effects on postnatal well-being.
Here, the domestic pig (Sus scrofa) was used to investigate PNS effects owing to the direct relevance for farm animal
welfare and the developing status of the pig as a large animal model in translational research. Pregnant primiparous
sows were exposed, in mid-gestation, to either a social stressor (mixing with unfamiliar conspecifics)
or were kept in stable social groups. The ratio of levels of mRNAs for corticotropin releasing hormone (CRH) receptors
1 and 2 in the amygdala, measured for the first time in the pig, was substantially increased in 10-week old
female, but not male, PNS progeny indicating a neurobiological propensity for anxiety-related behaviour. Mature
female offspring were observed at parturition in either a behaviourally restrictive crate or open pen. Such
PNS sows showed abnormal maternal behaviour in either environment, following the birth of their first piglet.
They spent more time lying ventrally, more time standing and showed a higher frequency of posture changes.
They were also more reactive towards their piglets, and spent longer visually attending to their piglets compared
to controls. Associated with this abnormal maternal care, piglet mortalitywas increased in the open pen environment,
where protection for piglets is reduced. Overall, these data indicate that PNS females have their brain development
shifted towards a pro-anxiety phenotype and that PNS can be causally related to subsequent impaired
maternal behaviour in adult female offspring.