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You Had a Baby Girl Because You Were Stressed as Hell, Study Says

File this one under Studies We Don’t Exactly Know What to Do With:

A study from Columbia University Vagelos College of Physicians and Surgeons and New York–Presbyterian claims that maternal stress during pregnancy may actually affect fetal and child development — including the sex of your baby. Hey, there are currently studies out there searching for the “gay gene” too, so just go with it.

The study appeared online in PNAS, the journal of the Proceedings of the National Academy of Sciences. Catherine Monk, Ph.D., is a professor of medical psychology at Vagelos College as well as director of women’s mental health at the Department of Obstetrics & Gynecology at New York–Presbyterian/Columbia University Irving Medical Center. Monk served as the study leader.

“The womb is an influential first home, as important as the one a child is raised in, if not more so,” Monk said of the reasoning behind the study. We beg to differ with Monk, as the womb is a short-term rental, more like an AirBnB stay for baby. The family one is born into is, well, a life sentence, if we’re being frank. But we get the idea: The stress levels of a mother-to-be may affect a fetus more than previously realized.

Monk and her colleagues studied in depth 27 indicators of stress — including physical, emotional, psychosocial, lifestyle — in 187 healthy pregnant women between the ages of 18 and 45. We were surprised to find that only 17% (that’s just 32) of the pregnant women were psychologically under stress, showing diagnosable levels of anxiety and depression. Another 16% (30 women) presented with high blood pressure or high caloric intake and were considered physically stressed. The rest of the women were considered to be healthy (67%, 125 women).

So what of these numbers? Well, the research was intriguing: The sex ratio of male births to female births in the stressed subsets of women showed more females born.

“Other researchers have seen this pattern after social upheavals, such as the 9/11 terrorist attacks in New York City, after which the relative number of male births decreased,” Monk explained. “This stress in women is likely of long-standing nature; studies have shown that males are more vulnerable to adverse prenatal environments, suggesting that highly stressed women may be less likely to give birth to a male due to the loss of prior male pregnancies, often without knowing they were pregnant.”

So…that double X chromosome is a powerhouse, is our takeaway. (Can’t say we’re shocked, exactly. Have you met any women?)

The study offered other insights as well. For instance, physically stressed moms were more likely to experience premature labor and birth than unstressed moms. And researchers wrote that fetuses of stressed moms showed “reduced heart rate…an indicator of slower central nervous system development — compared with unstressed mothers.”

Interestingly, the amount of social support offered to a mother seemed to make it more likely that the mother would give birth to a male child. But again, that would suggest that the mother-to-be was already receiving plenty of everyday support before she presumably got pregnant — and the sex organs of the baby were formed. A baby shower and spa day at 20 weeks pregnant does not magically revert a female fetus to a male fetus, in other words. (Duh.)

So, um, let’s say if all women were waited on hand and foot and screened daily for depression; would we then be risking…a planet full of men? Because, uh, it already feels like we’re living ON A PLANET FULL OF MEN. I, for one, am happy to take some hard knocks during pre- and early pregnancy to ensure the planet gets all the females it needs.

But that girl-making stress is far from a boon: Thirty percent of pregnant women in the study reported job stress or mental illness issues, both of which are linked to premature births, which in turn are linked to higher rates of infant death — as well as higher rates of ADHD and other issues in childhood.

“We know from animal studies that exposure to high levels of stress can raise levels of stress hormones like cortisol in the uterus, which in turn can affect the fetus,” Monk explained. “Stress can also affect the mother’s immune system, leading to changes that affect neurological and behavioral development in the fetus. What’s clear from our study is that maternal mental health matters, not only for the mother but also for her future child.”

Yeah, but a lot of other things also supposedly matter when it comes to fetal development; e.g. if Dad has been pounding too many IPAs. Let’s just say there’s still a whole lot to unpack regarding conception and pregnancy, and this is yet another study we’re taking lightly. No one wants stress raining down on pregnant women, but maybe the human race has found way to reset itself after wars and terrorist attacks and other violence perpetuated (primarily) by men — by creating stress that actually limits how many more males can enter the world. Not hard science, but definitely food for thought.

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