SAN FRANCISCO – Dr. Meg Autry typically spends a first prenatal care visit talking about what her pregnant patient may have heard – the myths and the facts – regarding the dos and don’ts during pregnancy.
She’s not alone. Patients hear plenty of prenatal myths perpetuated not only by their peers but by some health care providers, she said at a meeting on antepartum and intrapartum management sponsored by the University of California, San Francisco.
An informal electronic poll of the physicians, nurses, and nurse-midwives at the meeting showed that 63% discuss diet at a new patient visit, 17% talk about environmental exposures, 12% discuss exercise, and 8% discuss dietary supplements. These topics were generated more by the health care providers than by the patients, they said.
Deli meats were the leading dietary topic, discussed by 34%, followed by cooked fish, sushi, vegetarian diets, and cheese, in that order. Most of the questions about exercise come from women who exercise a lot, 73% of respondents said, than from women who don’t exercise enough (27%). Iron led the list of supplements discussed (by 36%), followed by omega-3 fatty acids, and (in a third-place tie) calcium and vitamin D.
Dr. Autry, professor of ob.gyn. and reproductive sciences at the university, offered the following myth busters and evidence-based advice for prenatal care. "My goal is to give you a basis for what you talk about with patients," she said.
• Fish: A food that’s high in quality protein, low in saturated fat, and full of beneficial omega-3 fatty acids comes with a downside: Methylmercury that can impair fetal and newborn motor and cognitive skills. Two prospective studies of dietary fish’s effects in pregnancy produced conflicting results. One study that found adverse effects from daily eating of fish was conducted in the Danish Faeroe Islands, where much of what they ate was whale. The other study, in the Pacific Ocean’s Seychelles Islands, found infant neurodevelopmental benefits when mothers ate fish in 12 meals/week, including types of fish that were more similar to those eaten in the United States, Dr. Autry said.
The Food and Drug Administration and Environmental Protection Agency in 2004 advised consumers to eat up to 12 ounces (two average meals) per week of a variety of fish that are low in mercury and to check local advisories about the safety of locally caught fish.
Encourage women to eat fish, she said, "but don’t eat fish that live for a long time and that eat lots of other fish," such as shark, swordfish, king mackerel, tilefish, whale, or albacore tuna.
• Sushi: Very rare infectious diseases from raw fish are virtually a nonproblem in the United States, because most sushi is flash frozen, which kills most pathogens. "I don’t think you need to tell patients they need to stop eating sushi," she said. "Talk to them more about mercury" and talk about the benefits of eating moderate amounts of fish.
• Supplements: There’s no evidence that taking a supplement to get omega-3 fatty acids is beneficial, especially compared with eating fish. "We’re just supposed to eat it, we’re not supposed to have a pill to fix everything," she said.
A standard prenatal vitamin supplies the iron and other vitamins and minerals needed, and it’s good to advise patients to eat foods that promote iron absorption and are high in vitamin C, such as strawberries or broccoli. Warn women that their prenatal vitamin should be their maximum dose of vitamin A, a known teratogen. There’s no good evidence that taking extra calcium or vitamin D supplements generally is helpful in pregnancy, but the American College of Obstetricians and Gynecologists recommends considering vitamin D supplementation in women at risk of deficiency.
• Cheese: A third of U.S. cases of listeriosis occurs in pregnant women and is associated with miscarriage and stillbirth. Nationally, the bacteria Listeria reaches people most commonly through hot dogs. In California, it’s the queso fresco. The FDA and/or the U.S. Department of Agriculture advise pregnant women not to eat hot dogs or luncheon meats unless they’re reheating to steaming, and to avoid soft cheeses; refrigerated pâtés or meat spreads; smoked seafood; raw or unpasteurized milk; and raw or undercooked meats.
• Caffeine: Approximately 85% of U.S. women report eating or drinking caffeine-containing food or drinks, Dr. Autry said. Concerns that caffeine consumption might be associated with low birth weight, congenital anomalies, delay in conception, or miscarriage were poorly designed and confounded by an association between caffeine intake and cigarette smoking. More recent studies predominantly have been negative, and a randomized, controlled trial found no association between moderate caffeine intake and gestational age or birth weight (BMJ 2007;334:409).