Over the last few days, science writers Amanda Schaffer and Annie Murphy Paul have been having a fascinating exchange about Paul’s new book Origins: How The Nine Months Before Birth Shape The Rest Of Our Lives.
The two writers dissect studies of how a mom’s behavior, diet, and environment affect her baby, but they also pull apart big ideas about evolution and the push and pull between mom and fetus.
As we know, when pregnancy studies make the news we often see big, flashy, guilt-inducing headlines, but Paul makes the distinction between small studies that we should approach with skepticism and those that are large and well-designed.
For example, a study published in the Lancet in 2007 looked at 12,000 women and found those who eat less than 12 oz of seafood per week are more likely to have children with increased risk for low verbal IQ, social and communication problems, and poor fine motor skills.
Another substantial study in the American Journal of Obstetrics and Gynecology found that women who gain more weight in pregnancy, even within the 25-35 pound guidelines, are more likely to have a heavier three year old.
But according to Paul, it’s not just about isolated variables like fish and pregnancy weight. What’s going on around the woman during pregnancy — the greater environmental conditions — shape what’s going on in the womb.
For example, in times of extreme stress (like in the wake of an earthquake), fewer boys are born. Why would that be?
Some studies of large-scale stress, like an earthquake in Kobe, Japan or the collapse of the Berlin wall, found a dip in boy births following the event. The theory is that weak boy babies are less likely to survive than weak girl babies. So in stressful times, boy fetuses will be more likely to abort, giving the mom another chance to get pregnant and have a girl, or a stronger boy.
Indeed, there is evidence that newborn boys are slightly more vulnerable than girls. And as Paul writes, Berkeley professor Ralph Catalano studied records of males born between 1751 to 1912 and found that when proportionally fewer boys were born (indicating times of stress), those men that were born had longer lifespans. Survival of the fittest?
It’s a truly fascinating field and I highly recommend reading the full discussion between the two writers, as well as a review of the book by Babble writer Ceridwen Morris.
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