SAN FRANCISCO — In the general ob.gyn. practice of Amy Meg Autry, M.D., visits with pregnant patients have evolved from giving equal time to examination and counseling to about 2% to examination and 98% to counseling.
Dr. Autry of the University of California, San Francisco, researched answers to some of their most common safety concerns regarding pregnancy and offered an overview of her findings at a meeting on antepartum and intrapartum management sponsored by the university:
▸ Fish. While eating fish can be good for maternal cardiovascular health and fetal growth and development, fish accumulate methyl mercury in their muscles from industrial pollution, which may cause neurotoxic symptoms in neonates that resemble cerebral palsy.
Only one retrospective study has found severe neurotoxic effects in children born to Japanese women who ate a steady diet of fish with high levels of mercury, even though the mothers showed minimal or no effects of mercury ingestion. Three other studies found neurologic effects in Japanese adults who ate a similar toxic-fish diet or Iraqi adults who ate grain that had been pretreated with mercury.
Two prospective studies produced conflicting results. In one, a diet high in whale blubber was associated with delays in attention, memory, and small-motor function in serial testing of children through age 6 in the Faeroe Islands of Norway. A separate study of residents of the Seychelles Islands who ate 12 meals of fish per week found that they had mercury levels 10–20 times higher than average levels in U.S. residents, yet this exposure produced no long-term neurologic effects. Other prospective studies are ongoing.
A 2004 joint advisory for consumers issued by the Environmental Protection Agency and the Food and Drug Administration recommended that pregnant women not eat shark, swordfish, king mackerel, or tilefish, because they are high in mercury.
The advisory emphasized the positive benefits of fish and stated that pregnant women may eat up to 12 ounces (two average meals) per week of fish low in mercury, such as salmon, shrimp, pollack, and catfish. Canned light tuna has less mercury than albacore tuna. For local fish, consult local and tribal advisories that apply to your area, or limit ingestion to 6 ounces per week.
▸ Cheese and hot dogs. One-third of an estimated 1,500 cases of listeriosis each year in the United States are in pregnant women. They are more susceptible to the infection due to compromised immune systems. One in five pregnant women with listeriosis experiences a spontaneous abortion or stillbirth.
Although cases of listeriosis in pregnancy are rare and sporadic, it's prudent to avoid high-risk foods such as hot dogs or luncheon meats, unless they've been reheated to steaming. Avoid soft cheeses, refrigerated patés or meat spreads, unpasteurized milk, and raw or undercooked meats.
▸ Caffeine. No data substantiate concerns about adverse pregnancy effects caused by light to moderate caffeine consumption.
Many studies that suggested caffeine may raise the risk for low birth weight, spontaneous abortion, congenital anomalies, or conception delays are poorly designed and demonstrate study bias, she said. Most of these studies were confounded by an association between caffeine intake and cigarette smoking.
▸ Alcohol. Multiple small studies show deleterious effects of drinking even small amounts of alcohol during pregnancy. A 2002 study that followed children from birth to age 6, for example, found persistently smaller head circumferences, height, and weight in children of women who had less than one drink per day during pregnancy. A 2001 study found more aggressive behavior in children of mothers who had one drink per week during pregnancy.
▸ Hot tubs. Animal data suggest that maternal hyperthermia (a body temperature of 102 degrees) may lead to first-trimester spontaneous abortion or neural tube defects. A very poorly designed study in human subjects, which was published in 2003, found a higher rate of first-trimester losses in women who used a hot tub more than weekly within 4 weeks of their last menstrual period. A 2005 metaanalysis of 42 studies suggested an 86% increase in risk for neural tube defects if the mother used a hot tub, sauna, or electric blanket and developed a fever.
On average, a pregnant woman's core body temperature will reach 102 degrees after 15 minutes of soaking in 102-degree water or 10 minutes in 106-degree water.
Skip hot tubs in the first trimester, and limit soaking times or water temperature after that, Dr. Autry advised.
▸ Exercise. Getting hot from exercise is okay; there's no evidence that hyperthermia from exercise is teratogenic, she said. Even exercise at high altitudes appears safe.