Antibiotics Home > Macrobid and Pregnancy

Unless you're going to deliver soon, Macrobid is generally considered safe to take during pregnancy. In fact, this antibiotic is one of the most commonly used antibiotics for treating urinary tract infections in pregnant women. It should not be taken by women who are more than 38 weeks pregnant, however, as this could increase the risk of red blood cell problems in the newborn.

Is Macrobid Safe While Pregnant?

Macrobid® (nitrofurantoin monohydrate/macrocrystalline) is a prescription antibiotic used to treat bladder infections. This drug is usually considered safe for use during pregnancy, although the full risks are not currently known.

What Is Pregnancy Category B?

The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category B is given to medicines that have not been adequately studied in pregnant humans but do not appear to cause harm to the fetus in animal studies.
In most animal studies, large doses of nitrofurantoin (the active ingredient in Macrobid) did not cause any problems during pregnancy. One animal study suggested that extremely high doses might be linked to poor growth and minor birth defects, but such problems were not seen with lower doses, which were still higher than those used in humans.
Another study suggested that high doses of nitrofurantoin may cause lung tumors. It is unclear what exactly the results of these animal studies mean for human use of the drug.
It should be noted that problems seen in animal studies, which often involve very high doses of medication for long periods, do not necessarily reflect what happens with humans. Pregnant women can be assured that Macrobid and other nitrofurantoin products are some of the most commonly used antibiotics for urinary tract infections during pregnancy.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
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