Foods for Your Baby’s Healthiest Future

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A pioneering study of prenatal influences on a child’s later health has yielded a trove of intriguing findings, including links between Vitamin D and asthma, fish and cognition. By Annie Murphy Paul, author of Origins: How the Nine Months Before Birth Shape the Rest of Our Lives

In a research lab located just outside Boston, there is a freezer filled with the physical artifacts of more than two thousand pregnancies: vials of blood drawn from women during pregnancy; tubes filled with their babies’ umbilical cord blood, collected immediately after delivery; more blood samples from women and their offspring, taken when the children reached three and then seven years of age. This corporeal evidence is supplemented by voluminous records kept on the mother-child pairs, beginning in pregnancy and extending through childhood. The files include women’s weight and blood-pressure readings during pregnancy, as well as the results of blood tests and details of labor and delivery; the answers to detailed questionnaires about women’s diets, physical activity, and home environment during pregnancy; the scores on developmental tests given to children at periodic intervals beginning in infancy; children’s medical diagnoses, medication use, and bodily measurements.

All this information has been gathered for Project Viva, a pioneering study of prenatal influences on later health. This longitudinal cohort study — that is, one that follows a single group of people over many years — is the brainchild of Matthew Gillman, professor of population medicine at Harvard Medical School. I met with Gillman one afternoon in his sunny office in a brick medical building in Boston. Balding and bushy-browed, Gillman has a steady intensity leavened by an appealingly dry sense of humor. In the mid-1990s, he became intrigued by the emerging idea that what happens very early in life can have effects on the health of babies, children, and perhaps even adults. “When I first read the work of David Barker on birth weight and later health, I was skeptical. There’s a lot that happens between birth and adulthood, and I wasn’t convinced that prenatal influences had much impact,” Gillman tells me. But he kept reading, and within a few years he published an article charting the evolution of his thinking, titled “The Fetal Origin of Adult Disease: From Skeptic to Convert.” Gillman wanted to conduct a study of the effects of childhood experience on later health, “but Barker had started me wondering: when does childhood really begin? I think it begins before birth, and so my study would have to start there, too.”

With a grant from the National Institutes of Health, Gillman began recruiting subjects for Project Viva in 1999, ultimately enrolling 2,670 pregnant women. All of the participants in the study were members of a Harvard-affiliated health-maintenance organization, and so (with participants’ permission) Gillman and his staff were able to have unusual access to their subjects’ complete medical records in addition to the questionnaires and biological samples gathered specifically for the study. From the beginning of Project Viva, Gillman decided to focus on the early life origins of three outcomes in particular: asthma and allergies, neurocognitive development, and obesity and heart disease. The study has already yielded a trove of intriguing findings.

Such as: The children of women who have a higher intake of vitamin D during pregnancy are less likely to show early signs of asthma. A study of 1,194 Project Viva mothers and their three year-old offspring, published in 2007 in the American Journal of Clinical Nutrition, found that women who consumed the greatest amount of vitamin D had children with the lowest risk of asthma. This was the case whether the nutrient came from supplements or from dietary sources like liver, eggs, and dairy products.

And: Eating a lot of fish during pregnancy seems to produce smarter kids. A study of 135 Project Viva mothers and their six month-old babies, published in 2005 in the journal Environmental Health Perspectives, found that greater fish consumption during pregnancy was associated with better infant cognition. The highest scores on a test of visual recognition memory were found among the offspring of women who ate more than two servings of fish a week during pregnancy, but had relatively low levels of mercury in their blood; similar results were found when another group of 341 Project Viva children were tested at three years of age. Pregnant women should eat plenty of fish, concluded Harvard Medical School assistant professor and Project Viva investigator Emily Oken, but they should choose varieties low in mercury and high in the “good” omega-3 fats, such as sardines and salmon.

And: Women who gain less than the recommended amount of weight during pregnancy are less likely to have overweight children. A study of 1,044 Project Viva mothers and their children found that greater weight gain during pregnancy was associated with a higher body mass index in three-year-old children. Women who gained excessive or even appropriate amounts of weight, according to the guidelines set by the Institute of Medicine, were four times more likely to have an overweight toddler than were women who gained less than the IOM advises (between twenty-five and thirty-five pounds for normal-weight women). “New recommendations for gestational weight gain may be required in this era of epidemic obesity,” concluded the study — and indeed, data from Project Viva were instrumental in devising the most recent set of recommendations, which places a stricter limit on the amount of weight obese women should gain during pregnancy.

The goal of Project Viva is not simply to generate research findings, Gillman says, but to devise effective interventions during pregnancy to improve the later health of the offspring. He knows this is a tall order. “Behavior is not easy to change. And pregnant women may encounter social and behavioral contexts that make change even more difficult — they may live in communities where fast-food restaurants far outnumber stores selling fresh fruits and vegetables, for example.” Still, he says, “Women want to do the best they can by their fetuses, and pregnancy is a time when they may be more open to change. If we can intervene in the right way, we can achieve beneficial health outcomes without freaking women out.” On this point, he is adamant: “This is not about blaming women or making them more anxious than they already are.”

Gillman’s colleague Emily Oken agrees. “There does seem to be a lot that a woman can do during pregnancy to improve the health of her offspring, but that doesn’t mean we should place all the responsibility on her shoulders,” she tells me. “For one thing, the mother’s physiology and behavior may well have been shaped by her prenatal experience, and the same with her mother, so how far back do you go?” And, Oken points out, prenatal experience isn’t the end of the story. “If a woman gains a lot of weight during pregnancy, for example, that doesn’t mean that her offspring are doomed to a lifetime of obesity. It means that they’ve been pointed on a particular trajectory, but if they go on to eat sensibly and exercise — perhaps with the help of an intervention program — that trajectory can be altered. So, our research can help target for intervention children who are at higher risk because of their fetal experience.”

What makes us the way we are? Some say it’s the genes we inherit at conception. Others are sure it’s the environment we experience in childhood. But could it be that many of our individual characteristics — our health, our intelligence, our temperaments — are influenced by the conditions we encountered before birth? In her new book Origins: How the Nine Months Before Birth Shape the Rest of Our Lives, Annie Murphy Paul, a journalist whose writing has appeared in The New York Times Magazine, Slate, Discover, and The Best American Science Writing, among other publications, explores the rich history of ideas about how we’re shaped before birth. You can follow her on Twitter @anniemurphypaul.



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