Morning sickness is such a hallmark of early pregnancy that for some women, it's the first sign that they're expecting.
But despite the pervasiveness of pregnancy-related nausea, there is still no easy treatment, since most expecting mothers and their doctors aren't keen on exposing a still developing fetus to medications. Now, researchers from Israel and Canada report in the New England Journal of Medicine that a commonly prescribed heartburn drug, which also has anti-nausea properties, may be used in pregnant women without causing harm to babies.
The drug, metoclopramide, is not approved by the U.S. Food and Drug Administration (FDA) for use in pregnant women, but it is dispensed widely in Europe and other places to treat morning sickness. In the new study, the largest one of maternal metoclopramide use to date, involving nearly 3,500 babies born between 1998 and 2007 in a region in southern Israel, the rate of congenital birth defects in babies born to mothers who used the anti-nausea drug was about the same as that in babies whose mothers had not (5.3% vs. 4.9%). What's more, the length of time pregnant women used the drug appeared to not affect the rate of abnormalities in their babies: 4.9% of women who took metoclopramide for up to one week in their first trimester went on to have babies with birth defects, compared with 6.1% of women who used the drug for more than three months.
"There are very few drugs approved for use in the first trimester of pregnancy," says Dr. Jennifer Niebyl, a professor of obstetrics and gynecology at the University of Iowa. "But this study could lead to metoclopramide getting approved to treat morning sickness because this is good data with big numbers."
Until now, there have been only about half a dozen studies looking at metoclopramide as a treatment for morning sickness. Even taken together, these studies include only about 500 babies. Because of the paucity of data, most doctors have prescribed the drug for nausea infrequently and only as a last resort for instance, in cases where nausea and vomiting are so severe that a woman cannot function. Most mothers-to-be in the U.S. are given antihistamines instead, which help calm queasiness with few lasting effects on the fetus; the only downside for moms is side effects like drowsiness.
Overseas, however, physicians have prescribed metoclopramide more liberally, and Dr. Gideon Koren, director of the University of Toronto's Motherisk Program for the study of antenatal drugs, saw an opportunity to address divided concerns about the medication. Collaborating with a large HMO in Israel, he and his multinational colleagues studied metoclopramide use in pregnant women and its association with babies' health outcomes specifically, birth defects, premature birth, low birth weight, Apgar score (which provides an immediate measure of a baby's physical condition at birth) and infant death.
The group was able to study six times as many babies exposed to metoclopramide as had ever been studied before, giving the results considerable weight. "I do think the FDA should look at it as a treatment for morning sickness," says Koren.
But before that can happen, he warns, more studies need to be done on how well metoclopramide actually controls nausea. At the moment, the drug, which calms digestive activity by slowing the contraction of intestinal muscles, is approved by the FDA only for the treatment of heartburn and other intestinal disorders. The drug's mechanism is believed to combat nausea by relieving the spasms that prompt queasiness. "What happens when people vomit or feel nauseous is that everything is stopped up," says Koren. "Metoclopramide helps move things forward and does not cause sedation like antihistamines."
Only additional studies can determine whether metoclopramide or an antihistamine is the better treatment for the nausea that accompanies hormonal changes in pregnancy. The new study should help those future studies along, since it now appears that exposing babies to metoclopramide does not put them at increased risk of developmental abnormalities. "These findings may change practice and help people to be less hesitant to use the drug," says Niebyl.