Scarring in utero, or damage to the fetus’ natural development during pregnancy, is a scientific argument that explains a phenomenon where populations who undergo damaging stressors like famines or infectious disease epidemics end up with infants who have a low life expectancy.
In a study published in the Journal Epidemiology, co-author, Tim Bruckner, PhD, professor of health, society, and behavior at the UC Irvine Joe C. Wen School of Population & Public Health, found an unexpected result that contradicts the previous understanding of scarring in utero. Bruckner and his colleagues analyzed male and female life expectancy and birth cohort data from 1751-1800 in Sweden, due to their famine in 1773.
The results showed that as a birth cohort ages, the frailest members die leaving behind a smaller but more resilient group. When environments become more damaging, we found that genetically weaker members passed away leaving behind fewer, but more robust members, who exhibit lower-than-expected mortality rates at later ages. This theory aligns not only with the results from using historical Swedish data but also with other empirical research studies at other places and historically damaging periods such as the Finnish famine (1866–1868) and China’s Great Leap Forward Famine (1959–1961).
These unexpected findings of an inverse association add to the need for further research on scarring and selection in utero. Understanding the diversity of frailty as characterized by their risk for disease, disability, and death will help us identify individuals who need public health interventions.
