The findings, published in the journal Nature Communications, revealed that the trauma children experience from living in war zones, natural disasters or perhaps even epidemics can have unexpected effects that resurface later in their lives.
During the Second World War, thousands of Finnish women and girls volunteered to aid in the war effort as part of the paramilitary organisation 'Lotta Svard' exposing some to the trauma of war.
The researchers from the University of Turku and the University of Helsinki in Finland used extensive data collected on these volunteers to study the effects of childhood trauma on adults.
The study showed that young girls and women who served in the war became mothers earlier and had more children compared to women of the same age who did not participate in the war effort.
"If we can measure the effects of trauma on basic things such as the timing of motherhood, then it almost certainly has major effects on many of our other important behaviours, such as overall aversion to risk, sociality or the pace of sexual development," said study lead author Robert Lynch from the University of Turku.
The study has clear relevance for the millions of children and adults worldwide who experience trauma through wars.
However, relevance likely also extends to other sources of trauma, such as natural disasters or even the current Covid-19 epidemic.
According to the researchers, evolutionary theory predicts that individuals experiencing an unstable environment with high mortality are better off reproducing sooner rather than taking the risk of not having the chance later.
"A childhood trauma can influence people's adult lives in ways that they are unaware of, such as the timing of their motherhood," said Professor Virpi Lummaa from the University of Turku.