To keep a population steady, research shows it’s necessary to have an average of about 2.1 babies per family — known as a replacement rate. In Ukraine, fertility rates have remained under that threshold since 1990. Over the last two decades, the rate has often dropped below what experts call a “very low” fertility rate of 1.3, when a population begins to shrink at an ever increasing rate. In January 2021, a year before Russia’s full-scale invasion, the fertility rate was 1.16, according to national statistics.

“Ukraine had one of the lowest birth rates on the planet. And then a war broke out,” explains Brienna Perelli-Harris, a professor of demography at the University of Southampton who studies fertility rates in Ukraine. She says Ukrainian demographers are projecting the fertility rate could fall as low as 0.55 in 2023, though official statistics are not available.

Often after a war, there is a baby boom. It happened in the U.S. after World War II. Families are reunited and safety returns in peacetime. But in Ukraine, the preexisting low rates combined with the mass exodus of more than 8 million people have the potential to leave the country with historically low numbers of potential parents, rendering a boom unlikely.

Ukraine’s birth rate was already dangerously low. Then war broke out : NPR