Are Pregnant Women Really More Xenophobic?

Dear Annie,

Your optimism is contagious. You write persuasively about the hope of reducing childhood obesity by helping women with gestational diabetes. The study you cite, which suggests the benefit of controlling blood sugar during pregnancy, is compelling to me, too. If I were to pick the area in which outreach to pregnant women might most improve children’s later health, I’d choose diabetes control (in addition, of course, to basics like prenatal vitamins and omega-3 fatty acids). At the same time, I have not seen comparable evidence that reducing pregnant women’s stress can improve kids’ cognitive development to the extent that educational programs can. I’m also cautious about the promise that prenatal dietary supplements will turn out to forestall cancer later in life, another possibility you dangle in the book based mainly, it seems, on a small amount of early work in mice. (“It’s not science fiction,” a researcher tells you. “I think that’s where we’re headed.”)

When you say fetal origins research is “moving forward,” of course I agree. But maybe we should float even larger questions about how, exactly, a scientific field matures and becomes coherent. Certainly, it takes larger, better-designed studies, often involving federal money and broad institutional cooperation. The National Children’s Study, which plans to follow pregnant women and their kids until age 21, is an exciting and hopeful example. At the same time, new research tends to produce tensions – hypotheses that contradict each other, results that are at odds, mechanisms that are in dispute. Confronting these conflicts head-on is one way a field can advance. Like when journals see an emerging controversy and ask researchers to revise papers or perform more experiments to address the challenges of critics.

You seem wary, though, of a fetal-origins smack-down. You note that researchers Ralph Catalano and David Barker are both concerned with “the same process of fitting the fetus to the particular world on the other side of the womb” and that they are “not necessarily in tension.” (Catalano talks about natural selection in utero to “cull” weaker male fetuses; Barker stresses training fetuses in the womb for the metabolic environment they may encounter later on.) But to some extent, the two make different empirical predictions and have gathered contradictory evidence about how exposures in utero affect later health and longevity. In fact, in one of the papers you cite (regarding the lifespan of Swedish men), Catalano states explicitly that his results “conflict with the ‘fetal origins’ inference” of David Barker. When researchers you respect throw down the gauntlet, why not welcome the debate? What does Barker have to say about Catalano’s data?

In other words, as I think we agree, fetal-origins research has quickly become a crowded, motley field. To help it both mature and influence policy for the benefit of mothers’ and children’s health, I’d argue that some quality control is in order—call it “culling.” You are in a special position here, as the author of this thoughtful and engaging book. You have a real opportunity to help define this field in the popular imagination, to say which scientists belong at its center and which are peripheral, who’s serious and who’s a quack (and, let’s be honest, every trendy new science attracts its share of those).

I understand why you want to counteract the “poisonous emotional climate” in which pregnant women often find themselves. So I’m curious how you decided when to include speculative claims that might not make women feel so good. To choose just one: the assertion that during pregnancy women tend to become more xenophobic—and that this flows from an evolutionary adaptation. You cite an evolutionary psychologist-anthropologist who studied pregnant women’s responses to two essays, one written by a foreigner criticizing the United States and one written by an American praising it. This researcher, Daniel Fessler of UCLA, reported that women in their first trimester reacted more negatively to the critical essay and more positively to the praising one than women later in pregnancy. He interprets this as evidence that women early in pregnancy are more distrustful of foreigners—and that this is driven in part by an evolved, protective mechanism. Early in pregnancy, Fessler suggests, the immune system is most suppressed and women are most susceptible to infectious disease. “The motivation behind such evolved protective reactions remains below our awareness,” you write, “even as these feelings steer us away from potential harm—say, from outsiders who might be carrying diseases against which we lack immunity.”

I have to ask: What was it about this work that caught your fancy? Surely not the quality of the science: This researcher relied on a small, unrepresentative sample of pregnant women recruited on the Internet. And his measure of “xenophobia”—responses to two essays about the United States—seems somewhat indirect. I wonder, too, about the assumption that pregnant women are most vulnerable to infectious disease in the first trimester. I might believe fetuses are more susceptible to many pathogens early on. But when it comes to pregnant women, I’m not sure it’s so easy to generalize. During last year’s last year’s swine flu outbreak, pregnant women seemed more likely to suffer serious complications or die during their third trimesters. And at least a few other infectious diseases seem to follow similar patterns. Fessler cites a review of immune cell function, but it doesn’t strike me as terribly up-to-date.

My point is, it’s as if you threw a large party and had to contend with an unwieldy guest list. In the living room, you’ve got serious public health-minded researchers talking soberly about obesity. But out on the fire escape, some guy is carrying on about pregnant women hating foreigners. Reading the book—and your smart, passionate, entries here, steeped in concern for women and children’s health—I just know that your heart is with the former group. And I imagine that as a gracious host, you were simply too polite to give the other guests a hard time. But, Annie, you are now a prominent voice on fetal origins research, and as your fan (and friend), I’d love for you to begin to challenge xenophobia man and his ilk, if not disavow them. I think your argument would be stronger for it.

If you disagree, of course, I’ll have to plead my case again another time, since this is where I sign off. It’s been a great pleasure chatting with you here, as it always is in person.


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