Pregnant women are public property

Take Back Your Pregnancy

When I got pregnant three years ago, I knew that I'd face lots of decisions—whether to have coffee or a glass of wine, what kind of prenatal testing to do, whether to use an epidural. I figured that I'd study the pros and cons and then make my own informed choices, as I normally did (with guidance and information from my doctor, of course).

This isn't what it was like at all.

In reality, medical care during pregnancy seemed to be one long list of rules. Being pregnant was a good deal like being a child again. There was always someone telling me what to do, but the recommendations from books and medical associations were vague and sometimes contradictory. It started right away. "You can only have two cups of coffee a day." I wondered why. What did the numbers say about how risky one, two or three cups were? This wasn't discussed anywhere....

When I asked my doctor about drinking wine, she said that one or two glasses a week was "probably fine." But "probably fine" isn't a number. In search of real answers, I combed through hundreds of studies—the ones that the recommendations were based on—to get to the good data. This is where another part of my training as an economist came in: I knew enough to read the numbers correctly. What I found was surprising.

The key problem lies in separating correlation from causation. The claim that you should stop having coffee while pregnant, for instance, is based on causal reasoning: If you change nothing else, you'll be less likely to have a miscarriage if you drink less coffee. But what we see in the data is only a correlation—the women who drink coffee are more likely to miscarry. There are also many other differences between women who drink coffee and those who don't, differences that could themselves be responsible for the differences in miscarriage rates....

I knew I didn't want to snack directly on listeria bacteria, but I wondered how much I could limit my risk by avoiding certain foods. What share of listeria infections was due to soft cheeses, for instance? It turns out that queso fresco, a Mexican soft cheese, has been implicated in about 20% of listeria outbreaks since 1998, and deli turkey in 10%. The rest of the recent outbreaks seemed random. One involved cantaloupe, another one, celery.

I concluded that avoiding queso fresco and deli turkey was a good idea, but in the end I didn't feel that it made sense even to exclude other deli meats. My best guess was that avoiding sliced ham would lower my risk of listeria from 1 in 8,333 to 1 in 8,255. I just didn't think it was worth it. It would have made more sense to avoid cantaloupe.