That old wife’s tale that women who get ‘big’ in pregnancy give birth to boys might have something in it after all. For it does indeed now seem that those of us who gain more weight during pregnancy are more likely to have a boy. Or so a new study suggests.
After analysing data on more than 68 million births over 23 years, US researchers at the University of Georgia found that, overall, 51% of babies born are boys. But the likelihood of having a boy does increase according to the amount of pregnancy weight gained.
So when we gain 20lb during pregnancy, roughly 39% of babies we have are boys. But, if we gain 40lb, then 52.5% of our babies are boys. And at 60lb, about 54% are boys. But above 60lb the correlation disappears.
The researchers say it’s not yet clear why there’s this correlation in mums’ weight gain with the sex of their baby. But study leader and endocrinologist Kristen J Navara says that male embryos and foetuses have higher metabolic rates so they require more nourishment to develop successfully. Therefore, putting on less weight in pregnancy may be more harmful to a boy foetus than a female one.