Stressed Mothers Have More Girls — a Lot More Girls

Here’s some advice for men who want a son: Be nice to his future mother. Yet more research has now demonstrated that women harrowed by physical and psychological stress during pregnancy are less likely to have a boy.

– Haaretz Weekly Ep. 44

Haaretz Weekly Ep. 44Haaretz

How less likely, exactly? In general, human procreation is biased toward males: Globally, 105 boys are born for every 100 girls. This make evolutionary sense if you figure that young boys are more likely to die than young girls — whether because they’re more daring, more annoying, or more stupid (to sum up: more likely to play chicken). Our long-term evolution did not factor in polygamy.

But physically stressed women produce nine girls to every five boys; that’s almost twice as much. Psychologically stressed women produced three girls for every two boys, report researchers at Columbia University Vagelos College of Physicians and Surgeons and NewYork-Presbyterian.

The statistical study was published this week in the Proceedings of the National Academy of Sciences.

That is quite the difference. It bears adding that the study was a very small one: The team examined 187 healthy women, that’s all. Of these, 32 (17 percent) were found to be psychologically stressed with clinically meaningful levels of depression, anxiety and perceived stress. Thirty (16 percent) were physically stressed, with high blood pressure and overeating; and the majority, 125 (nearly 67 percent), were not stressed.