Study Finds Serious Side Effects in Drug to Delay Preterm Labor

SAN FRANCISCO (KCBS) -- A new study by Stanford researchers found that magnesium sulfate, used to delay preterm labor in women, has side effects that include vomiting, shortness of breath and double vision.

Researchers compared magnesium sulfate to another drug called nifedipine, which they say often leaves women feeling better, and has a much lower rate of causing the serious side effects.

In terms of delaying delivery, there are no differences between the two drugs, according to Dr. Deidre Lyell of Stanford University's Lucille Packard Children's Hospital. "With magnesium, the side effects that we saw most commonly were things that are pretty unpleasant. Vomiting, shortness of breath, lethargy, blurry vision, double vision, so to a woman who is actually in preterm labor and trying to face the terrorizing prospect that she may have a very premature newborn, it's pretty troubling to lay on those side effects on top of all the other anxiety," Lyell said.

Researchers also found no difference in the birth weight of infants who received magnesium and those who were given nifedipine. However, Lyell says nifedipine does lower blood pressure by about 10 percent, and for that reason, can be dangerous for women who already have low pressure. "We're all different biologically and what works well with one person may not work as well with another," she said. In one rare case a woman on nifedipine had a heart attack.

Lyell said neither drug should be used unless a doctor is certain the woman is in labor.

Link to this article
Listen to the full interview