The human fetus has evolved mechanisms to acquire information about the environment and guide its development. The human placenta is both a sensory and effector organ that incorporates and transduces information from its maternal environment into the fetal-developmental program. The fetal–placental unit’s detection of stress signals from the maternal environment (e.g., cortisol) ‘informs’ the fetus that there may be a threat to survival. This information primes or advances the placental clock, resulting in earlier delivery and escape from the hostile environment. Concurrently, the fetus adjusts its developmental trajectory, modifying its nervous system to ensure survival.
There is evidence that maternal cortisol and psychological distress during the prenatal period are associated with delayed cognitive development, at least through adolescence. The first study showing that a mother’s elevated pregnancy-specific anxiety (i.e., anxiety about her pregnancy and the health of her fetus) early in her pregnancy was associated with reduced gray matter volumes in her 6- to 9-year-old children was recently published. The affected regions were those associated with higher cognitive functions including reasoning, planning, attention, working and recall memory, language, and social and emotional processing.