ACOG approves use of some antibiotics in first trimester-with reservations

June 2, 2011

A new committee opinion issued by the Committee on Obstetric Practice of the American College of Obstetricians and Gynecologists (ACOG) concludes that giving sulfonamide and nitrofuran antibiotics during the first trimester of pregnancy is appropriate when no other suitable alternative antibiotics are available.

A new committee opinion issued by the Committee on Obstetric Practice of the American College of Obstetricians and Gynecologists (ACOG) concludes that giving sulfonamide and nitrofuran antibiotics during the first trimester of pregnancy is appropriate when no other suitable alternative antibiotics are available.

Sulfonamides and nitrofurans, which are often prescribed to treat urinary tract infections, were implicated as possible first-trimester teratogens in a 2009 report by researchers from the National Birth Defects Prevention study. But the committee opinion calls the evidence linking the antibiotics to birth defects “mixed.”

William H Barth, Jr, MD, chair of the Committee on Obstetric Practice, notes that the 2009 study had “several significant limitations, including recall bias” because women were asked about antibiotic use after pregnancy. “Furthermore, this was an observational study, so it’s impossible to know whether the birth defects were caused by the antibiotic or the infection itself, or some other factor,” Barth says. A third limitation was that the medical records didn’t confirm prescription of antibiotics; about 35% of patients couldn’t remember the specific name of the drug.

Because of these limitations and because other studies haven’t found an association between sulfonamides and nitrofurans and birth defects, ACOG says that the 2 antibiotics may be given during the first trimester in the absence of an alternative drug. During the second and third trimesters when the risk of birth defects is less, they can be used as first-line agents to treat and prevent urinary tract and other infections.

“Pregnant women should not be denied appropriate treatment for infection because untreated infections can commonly lead to serious maternal and fetal complications,” the committee opinion states. It cautions that “as with all patients, antibiotics should be prescribed for pregnant women only for appropriate indications and for the shortest effective duration.” The statement, “Committee Opinion No 494: Sulfonamides, nitrofurantoin, and risk of birth defects,” has been published in the June issue of Obstetrics & Gynecology (2011;117[6]:1484-1485).