This 2017 UC Irvine human review subject provided details of how fetal hypothalamic-pituitary-adrenal components and systems develop, and how they are epigenetically changed by the mother’s environment:
“The developmental origins of disease or fetal programming model predicts that intrauterine exposures have life-long consequences for physical and psychological health. Prenatal programming of the fetal hypothalamic-pituitary-adrenal (HPA) axis is proposed as a primary mechanism by which early experiences are linked to later disease risk.
Development of the fetal HPA axis is determined by an intricately timed cascade of endocrine events during gestation and is regulated by an integrated maternal-placental-fetal steroidogenic unit. Mechanisms by which stress-induced elevations in hormones of maternal, fetal, or placental origin influence the structure and function of the emerging fetal HPA axis are discussed.
Human gestational physiology and fetal HPA axis development differ even from that of closely related nonhuman primates, thereby limiting the generalizability of animal models. This review will focus solely on studies of prenatal stress and fetal HPA axis development in humans.”
Every time I read a prenatal study I’m in awe of all that has to go right, and at the appropriate time, and in sequence, for a fetus to be undamaged. Add in what needs to happen at birth, during infancy, and throughout early childhood, and it seems impossible for a human to escape epigenetic damage.
1. The reviewers referenced human research performed with postnatal subjects, as well as animal studies, despite the disclaimer:
This review will focus solely on studies of prenatal stress and fetal HPA axis development in humans.”
This led to blurring of what had been studied or not with human fetuses regarding the subject.
2. The reviewers uncritically listed many dubious human studies that had both stated and undisclosed severe limitations on their findings. It’s more appropriate for reviewers to offer informed reviews of cited studies, as Sex-specific impacts of childhood trauma summarized with cortisol:
“Findings are dependent upon variance in extenuating factors, including but not limited to, different measurements of:
- early adversity,
- age of onset,
- basal cortisol levels, as well as
- trauma forms and subtypes, and
- presence and severity of psychopathology symptomology.”
3. It would have been preferable had the researchers stayed with their stated intention and critically reviewed only a few dozen studies with solid evidence of the review title: “Developmental origins of the human hypothalamic-pituitary-adrenal axis.” Let other reviews cover older humans, animals, and questionable evidence.
I asked the reviewers to provide a searchable file so that their work could be better used as a reference.
https://www.researchgate.net/publication/318469661_Developmental_origins_of_the_human_hypothalamic-pituitary-adrenal_axis “Developmental origins of the human hypothalamic-pituitary-adrenal axis” (registration required)