The concept is called prenatal flavor learning.
The flavor and odors of what mothers eat show up in the amniotic fluid, which is swallowed by the fetus, and in breast milk. There is evidence that fetal taste buds are mature in utero by 13 to 15 weeks, with taste receptor cells appearing at 16 weeks, researchers say.
“With flavor learning, you can train a baby’s palate with repetitive exposure,” said Kim Trout, director of the nurse midwifery/women’s health nurse practitioner program at Georgetown University.
Trout recently co-authored a paper that reviews the evidence on prenatal flavor learning and its implications for controlling childhood obesity and diabetes, among the country’s most pressing health problems. She is incorporating the concept into the curriculum of Georgetown’s two-year midwifery master’s degree program. Starting in January, the reproductive health course for first-year students will include that concept in the section on prenatal care and nutrition, she said.
As a practicing midwife, she also advises patients who want to know what they can do to maximize their baby’s health.
“I tell them there is good evidence that their babies could develop flavor preferences based on what they’re eating, and I also tell their partners if they are doing the cooking,” said Trout, who commutes between Washington and Philadelphia, where she sees patients at a private obstetrics-gynecology practice that is part of the University of Pennsylvania’s medical school and health system.
Some expectant mothers say the concept makes sense, and for those who enjoy eating a variety of food, so much the better.
“I’m not a picky eater. I love all foods,” said Elizabeth Hooks, 29, of Philadelphia, who is one of Trout’s patients. Hooks, 19 weeks pregnant, said she does not want her child to “be a member of the fast-food nation.” She added: “If I can start now, that’s wonderful.”
Hooks works in the corporate office of the retailer Anthropologie. Her lunch on a recent weekday included a wide sampling from the cafeteria salad bar: chicken and cranberry salad, asparagus, tomato and mozzarella salad, and fresh kiwi.
The concept of prenatal flavor learning is not widely known among the general population or among health-care professionals who take care of pregnant women.
But even those who aren’t familiar with the research say they don’t see a downside if the science can be used to encourage healthy eating.
“It’s a new one on me,” said Cynthia Bullock Flynn, a nurse-midwife and general director of the Family Health and Birth Center in the District. “It sounds very interesting. We certainly counsel moms to eat their vegetables when they’re pregnant.”
Sumi Sexton, a family-medicine physician in Arlington County and an assistant professor at Georgetown’s medical school, said practitioners encourage mothers-to-be to eat healthy foods as a way to model that behavior for their children.
“If the science supports it and the baby is getting an acquired taste through the amniotic fluid and breast milk, great,” she said. “It’s only reinforcing what I’m telling you to do anyway.”
Of course, that’s not to say that this approach will somehow lead to kids reaching for another helping of broccoli over chocolate cake. Children’s preference for sweets most likely evolved because sweet-tasting foods are high in energy, according to research, and their preference for salty foods is related to the need for minerals. Their rejection of bitter tastes most likely evolved because most poisonous compounds are bitter.
Exposing infants in the womb to the somewhat bitter flavor of vegetables, for example, makes those vegetables more palatable when offered as solid foods, researchers said.
Obviously, there are other factors that determine what people like to eat. And it’s very possible that a child will never learn to like broccoli no matter how much of it Mom ate while pregnant, Trout said.
She said researchers have also found that flavor learning prepares babies for the foods of their culture. If that culture features fast foods and large amounts of sweets, however, children will be at higher risk of developing diabetes and obesity.
Trout said she sees evidence in her own life. When she was pregnant with her daughter, she adhered to a strict nutritional plan that she taped to her refrigerator. Her daughter has a good diet and is a great cook, she said. Her son prefers fast food such as chicken wings, the kind of food Trout ate while working as an intern.
Just another reason to go heavier on the greens this Thanksgiving.