Lessons From the Womb
We must begin with the water-balloon condoms. In the 1950s, researchers balanced these on the bellies of pregnant women and sent sound waves through them, as part of the invention of medical ultrasound. This allowed them to peer into the womb for the first time, as you describe in your elegantly written book Origins. Early glimpses, like "grainy footage beamed back from the first moon landing," begot more sophisticated images, like the clay-colored, sculptural ones you got to see of your own son when he was in utero. I love these details, both for their own sake and as emblems of the scientific desire to eavesdrop on fetal life.
As you write, researchers have increasingly probed how a little "lima bean with a beating heart" interacts with its mama, her womb, and the chemical and sensory "postcards" it receives, care of her, from the outside world. You argue that old-school Western medicine often viewed the fetus as a "perfect parasite," relatively impervious to external influence—yet today, a burgeoning literature lays out the lasting influences of the mother's environment and behavior, including her diet, stress level, mood, and chemical exposures.
Much of the science you cite is powerful. Famine, poverty, obesity, disaster, war—all seem to cast long shadows over the future health of babies born following these exposures. You tell the story of Holland's "Hunger Winter," a devastating period at the end of World War II. Persuasive research suggests that the Dutch who were in utero at the time have a higher risk of heart disease, diabetes, and obesity as adults. Similarly, strong data suggest that people whose mothers were in early pregnancy during the 1967 Arab-Israeli War were more likely to develop schizophrenia later on.
Other studies left me doodling questions in the margins. You follow ongoing work, for instance, on a group of Canadian children who were in utero during a devastating 1998 ice storm, which left many of their mothers without heat or electricity for as many as 40 days. Researchers have published studies showing lingering effects of this stressful period on the cognitive and language skills of the children at age 2 and age 5 and a half. "Now ten years old, the children of women who encountered great adversity during the ice storm have displayed differences at every stage from kids whose mothers had an easier time," you write.
But what mechanisms do you think were at play? In the paper on the 5-and-a-half-year-olds, those whose mothers experienced high "objective stress," like more days without electricity or phone service, performed worse on cognitive tests. But those whose moms reported the greatest "subjective distress," meaning the most suffering in response to these events, were not worse off. Elsewhere, you talk about the possible role of maternal levels of the hormone cortisol in mediating stress-related effects on the fetus. So wouldn't you expect the kids whose moms felt most overwhelmed during the crisis to be the ones absorbing the greater impact? Also, most of the high-stress kids still perform above average on IQ tests, just not as well as the low-stress ones, as you note. So how meaningful do you think the disparities will be for them?
Of course, we all want to know how more quotidian factors, like tough work deadlines or summer margaritas, might affect the little lima bean. You sift, rather heroically, through the available evidence, which is often fragmented or contradictory, and conclude that in many cases no one really knows. For example, some data suggest that moderate anxiety in a pregnant woman doesn't harm her fetus—and may in fact boost his later development. (I buy this argument.) But not all researchers are convinced, and you judiciously describe both views. I wonder, now that you have a little more distance from the material, where do you come down?
I ask because when it comes to your own pregnancies, you seemed inclined to avoid risk when the evidence is murky or missing. While pregnant, you say you chose to avoid all alcohol, caffeine, and most medications, so far as possible. It's the better-safe-than-sorry approach, and for women who don't need, say, an antidepressant to feel sane, it's sensible. But what about the harder cases? You also worried about listeria, mercury, BPA, polyaromatic hydrocarbons, and other toxins (and I certainly relate to that). Yet at the same time, you argue that we should not misconstrue fetal research merely as "one long ringing alarm bell," a chorus of "No, Don't, Stop!" You're committed to a brighter spin, noting that a pregnant woman can have "a powerful and often positive influence on her child before it's born."
Philosophically, I'm with you. There is surely much continuity between "the individual in utero and the individual in the world," as you put it. More tangibly, though, what are the positive influences that a woman can exert and that science validates? Yes, she can take her vitamins, including folic acid, which protects from neural tube defects. She can eat fish rich in omega-3 fatty acids—or, my preferred solution, take fish oil supplements, which have little mercury. Overall, though, the research showing bad things to be bad (famine, poverty, war, thalidomide, DES, heavy alcohol) strikes me as far more extensive and powerful than the data suggesting good things to be good (yoga, meditation, therapy, cruciferous vegetables, green tea). What evidence am I missing?
Amanda Schaffer is a science and medical columnist for Slate.