Kids born on the wrong side of town disproportionately suffer addiction, stress, and depression. Girls from poor neighborhoods menstruate early and are more likely to face teenage pregnancy than their wealthier peers. Put succinctly, poor kids seem to mature faster — and suffer the disadvantages that come with facing adult challenges as children. Now, a collection of animal studies offers one possible reason why: Maternal stress may impact offspring, causing them to age prematurely.
The study was not conducted on humans and therefore cannot definitively answer any questions about how human children develop, cautions co-author on the study Andreas Berghanel of the University of New Mexico, in a statement. Still, he’s quick to add that “these new results may bear some translational value for understanding why girls start their menstrual cycles earlier in poorer neighborhoods.”
Poor kids certainly hit puberty before rich kids. Studies have shown that economically disadvantaged girls in the UK are twice as likely to start their periods early and that poor boys in Australia have a four-fold increase in rates of early puberty, as compared to rich kids. Unfortunately, early puberty puts kids at risk of a battery of health issues, including emotional, behavioral, and social problems, including eating disorders and early sexual debut. Preliminary research has also linked early puberty to reproductive cancers and heart disease later in life.
Figuring out why poor kids hit puberty early, then, ought to be a public health priority. In this new study involving 21 different mammalian species, Berghanel and colleagues found that prenatal maternal stress causes mothers’ bodies to invest fewer resources in their fetuses. In these cases, the fetus develops in “compensation mode”—essentially reprogramming itself to make the best of a bad situation and speed up growth as much as possible so that it’ll have a better chance of reproducing before it dies. One of the recurring outcomes of this pattern of development in mammals is early puberty, with all of its evolutionary advantages, and medical disadvantages.
This study is one of basic science and won’t solve the more complex problem of early puberty in poorer populations. But it might point other researchers in the right direction. The results indicate that maternal stress in early pregnancy increases the risk of babies developing in compensation mode, and imply that allocating more resources for disadvantaged pregnant women in their first trimesters could have long-term positive effects for their children.
“Maternal stress during gestation causes numerous effects on infant physiology that extend well into adulthood,” according to the study. “The results support an adaptive life history perspective on maternal effects that is relevant for evolutionary biology, medicine, and psychology.”