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Catherine Monk, an assistant professor of psychiatry at Columbia University, has advanced an even more startling proposal: that a pregnant woman's mental state can shape her offspring's psyche. "Research indicates that even before birth, mothers' moods may affect child development," Monk says. "Can maternal mood be transmitted to the fetus? If so, what is the mode of transmission? And how do such moods affect fetal development? These are new questions to be asking," she says. "We're still figuring out how to get fetuses to answer."
In fact, Monk and her colleagues have gone some way toward putting the fetus on the couch. At her lab, pregnant women who are depressed or anxious and pregnant women with normal moods are hooked up to devices that measure their respiration, heart rate, blood pressure and nervous-system arousal, as well as the movements and heart rate of their fetuses, and then subjected to challenging mental exercises. All of the women show physiological signs of stress in response to the tests, but only the fetuses of depressed or anxious women display disturbances of their own.
"This difference suggests that these fetuses are already more sensitive to stress," Monk says. "Perhaps that's because of a genetic predisposition inherited from the parents. Or it could be because the fetuses' nervous systems are already being shaped by their mothers' emotional states." Women's heart rate and blood pressure, or their levels of stress hormones, could affect the intrauterine milieu over the nine months of gestation, Monk explains, influencing an individual's first environment and thereby shaping its development.
The differences Monk has found among fetuses appear to persist after birth. And because basic physiological patterns like heart rate are associated with more general differences in temperament, Monk says, "it may be that the roots of temperamental variation go back to the womb."
It could even be the case that a pregnant woman's emotional state influences her offspring's later susceptibility to mental illness. "We know that some people have genetic predispositions to conditions like depression and anxiety," Monk says. "And we know that being raised by a parent with mental illness can increase the risk of mental illness in the offspring. It may be that the intrauterine environment is a third pathway by which mental illness is passed down in families." This kind of research, says Monk, "is pushing back the starting line for when we become who we are."
Back to the Future
Ten years ago, when Matthew Gillman, a professor of population medicine at Harvard University, launched Project Viva a study tracking more than 2,000 Boston-area children since they were fetuses he knew he wanted to explore the effects of childhood experiences on later health. "But David Barker's research had started me wondering: When do these experiences really begin?" says Gillman. "I came to think they begin before birth, and so my study would have to start there too." Already the project has begun to illuminate the fetal origins of asthma, allergies, obesity and heart disease, as well as the role of gestational factors in brain development.
There are more revelations on the way. This year, the first of 100,000 pregnant women began enrolling in the National Children's Study, a massive, federally funded effort to uncover the developmental roots of health and disease. Researchers are conducting interviews with the women about their behaviors during pregnancy; sampling their hair, blood, saliva and urine; and testing the water and dust in their homes. The women and their children will be followed until the offspring turn 21, and the first results from the study, concerning the causes of premature births and birth defects, are expected in 2012.
Another line of research is developing interventions aimed at preventing disease. David Williams, a principal investigator at the Linus Pauling Institute at Oregon State University, is testing the notion that certain substances consumed during pregnancy can provide offspring with lifelong chemoprotection from illness. In Williams' studies, the offspring of mice that ingested a phytochemical derived from cruciferous vegetables like broccoli and cabbage during pregnancy were much less likely to get cancer, even when exposed to a known carcinogen. After they were weaned, the offspring in Williams' experiments never encountered these protective chemicals again, yet their exposure shielded them from cancer well into maturity. He predicts that one day, pregnant women will be prescribed a dietary supplement that will protect their future children from cancer. "It's not science fiction," he says. "I think that's where we're headed."
Knowledge gleaned from fetal-origins research may even benefit those of us whose births are in the past. "I always ask my adult patients what their birth weight was," says Mary-Elizabeth Patti, an assistant professor at Harvard Medical School and a physician-scientist at the university-affiliated Joslin Diabetes Center. "Patients are often surprised at the question they expect me to ask about their current lifestyle. But we know that low-birth-weight babies become adults with a higher risk of diabetes, so having that information gives me a more complete picture of their case." Patti is researching how data about patients' birth weight could translate into tailored courses of treatment.
These possibilities may seem strange and surprising, but then the notion that we owe anything about our mature selves to our experiences during childhood was once considered preposterous too before Sigmund Freud first pointed our attention to those formative years. With time and evidence, the idea that our health and well-being are shaped during gestation could also come to seem commonsensical. Perhaps our children, whose first snapshots were taken not in a hospital bassinet but inside a uterus, won't find the idea of fetal origins odd at all.
As for me, the baby in my belly for those nine months is now a sandy-haired toddler named Gus. Where did his particular qualities come from? Will he be strong or sickly, excitable or calm? What will his future hold? These are the questions parents have long pondered about their children. More and more, it looks as if many of the answers will be found in the womb.
Adapted from Origins: How the Nine Months Before Birth Shape the Rest of Our Lives, by Annie Murphy Paul, published in September by Free Press