Agents that can cause mental and/or physical birth defects in the fetus when a woman is exposed to them during pregnancy are termed ‘teratogens.’ Alcohol, a number of prescription medications (including several antibiotics such as tetracycline), cocaine, certain heavy metals (lead, mercury), radiation, and some bacterial and viral infections are known teratogens. Fetuses are most vulnerable to teratogens in the first trimester when their organs and nervous system are forming.
“Antibiotics are commonly prescribed during pregnancy for a variety of bacterial infections, so there is considerable data now on the relationship of antibiotic exposure to birth defects,” said William H. Barth Jr, MD, chair of The College’s Committee on Obstetric Practice. Commenting on the 2009 study, Dr. Barth noted, “This study had several significant limitations, including patient recall bias. 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.”
Due to the limitations of this one study, and because other studies have found no risk of birth defects with nitrofurans and sulfonamides, The College says that these two antibiotics can be used by pregnant women in the first trimester if there is no alternative antibiotic. After the first trimester when the potential risk of these two antibiotics causing birth defects is lessened, they can be used as first-line agents for the prevention of urinary tract infections and other infections.
Committee Opinion #494 “Sulfonamides, Nitrofurantoin, and Risk of Birth Defects” is published in the June 2011 issue of Obstetrics & Gynecology.
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The American College of Obstetricians and Gynecologists (www.acog.org) is the nation’s leading group of physicians providing health care for women. As a private, voluntary, nonprofit membership organization of approximately 55,000 members, The American College of Obstetricians and Gynecologists strongly advocates for quality health care for women, maintains the highest standards of clinical practice and continuing education of its members, promotes patient education, and increases awareness among its members and the public of the changing issues facing women’s health care. Follow us on Twitter at www.twitter.com/acognews.