Pregnant Women Often Prescribed Unsafe Antibiotics

Diana Phillips

January 11, 2018

Despite recommendations against using sulfonamide antibiotics and nitrofurantoin in early pregnancy, both are commonly prescribed to women with urinary tract infections (UTIs) during their first trimester of pregnancy, a new study shows.

In an examination of antibiotic prescriptions filled by pregnant women with urinary tract infections in 2014, researchers from the Centers for Disease Control and Prevention (CDC) determined that the most frequently prescribed antibiotics during the first trimester were nitrofurantoin, ciprofloxacin, cephalexin, and trimethoprim-sulfamethoxazole. The researchers reported their findings in the January 12 issue of Morbidity and Mortality Weekly Report.

Because of the potential risk for birth defects, the American College of Obstetricians and Gynecologists recommends against prescribing sulfonamides and nitrofurantoin in the first trimester of pregnancy except in situations where other antibiotics are not clinically appropriate.

In the current study, Elizabeth C. Ailes, PhD, from the CDC's National Center on Birth Defects and Developmental Disabilities, and colleagues assessed compliance with these recommendations, which were issued in 2011. Using private insurance claims data from 2013 to 2015 derived from a commercial insurance database, the researchers identified 482,917 pregnancies among women aged 15 to 44 years with estimated delivery dates in 2014.

In the pregnancy cohort, 34,864 (7.2%) had an initial outpatient UTI claim 90 days before their estimated last menstrual period or during pregnancy. Of those, 41% occurred during the first trimester of pregnancy, the authors write.

Among pregnant women diagnosed with a UTI, 68.9% filled an antibiotic prescription, compared with more than 76.1% of women diagnosed during the 90 days before their estimated last menstrual period.

The type of antibiotic dispensed for women diagnosed during vs before pregnancy differed. Specifically, fluoroquinolones and sulfonamides were more commonly given to women before pregnancy (any trimester), whereas nitrofurantoin, cephalosporins, and penicillins were more commonly dispensed during pregnancy.

The most common antibiotics given during the first trimester of pregnancy were nitrofurantoin (34.7%), ciprofloxacin (10.5%), cephalexin (10.3%), and trimethoprim-sulfamethoxazole (7.6%), they report. Thus, more than 4 in 10 women treated received an antibiotic not recommended for use during pregnancy.

The findings highlight important considerations for antibiotic prescribing practices, both in general and specifically as they relate to sulfonamide antibiotics and nitrofurantoin in early pregnancy.

"Improving antibiotic selection is an important aspect of antibiotic stewardship and these antibiotics have potential risks associated with early pregnancy use, particularly during organogenesis," the authors write. "Given the recommendations to avoid these medications in early pregnancy if possible and the fact that nearly 50% of pregnancies in the United States are unintended, it is important that health care providers of various specialties be aware of these recommendations and that they might be 'treating

for two' when prescribing antibiotic treatments for UTIs to pregnant women and women who might become pregnant in the near future."

The authors note several limitations related to study design, including the fact that the pregnancies and UTI diagnoses were derived from diagnostic and procedure codes and not validated, the lack of clinical details related to the UTI diagnoses, reliance on a convenience sample from a commercial database, and exclusion of antibiotic prescriptions that were paid for out of pocket.

The authors have disclosed no relevant financial relationships.

MMWR Morb Mortal Wkly Rep. 2018;67:18-22. Full text

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