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HealthPartners study shows commonly used antibiotic is safe during pregnancy


November 24, 2015

BLOOMINGTON, Minn. — A new study by HealthPartners Institute for Education and Research answers safety questions about the use during pregnancy of a commonly used antibiotic. The medication is a combination of trimethoprim and sulfonamide (TMP-SUL) and is sold under brand names including Bactrim and Septra. It is often prescribed to treat infections including urinary tract infection, bronchitis, pneumonia, middle ear infection and traveler's diarrhea.

Evidence about the safety of TMP-SUL has been mixed, with some studies suggesting that use during the first trimester is associated with congenital malformations such as cleft palate, club foot or heart defects.

The HealthPartners study by researcher Pam Pawloski and colleagues looked at records for more than 7,000 infants at 11 U.S. health plans who were exposed to TMP-SUL. Researchers compared that group to infants who were exposed in the womb to penicillin and to infants that were not exposed to any antibiotic. Researchers found that the rates of heart, cleft palate, clubfoot and urinary system birth defects was relatively small (less than 1.5 percent) and was the same for all groups. The study is published in the Nov. 24. 2015 issue of Pharmacoepidemiology and Drug Safety.

“These results can give mothers and their providers reassurance that this antibiotic is safe to treat some of the most common illnesses,” said Pam Pawloski, a research investigator with HealthPartners Institute for Education and Research. Research about health issues affecting pregnant women and children are part of HealthPartners Children’s Health Initiative. It includes 10 areas of focus aimed at improving the health and well-being of children from pregnancy to age five. It’s Important because research shows there is a strong link between health and well-being early in life and health and well-being later in life.

About HealthPartners Institute for Education and Research

The HealthPartners Institute for Education and Research is part of HealthPartners, the largest consumer-governed, non-profit health care organization in the nation with a mission to improve health and well-being in partnership with members, patients and the community. It’s a 501c (3) nonprofit organization that conducts public-domain health research proposed and led by our researchers and in collaboration with investigators across the nation. Our health professional educators provide accredited graduate education, clinical simulation and other learning resources. For more information, visit

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Patricia Lund
Senior communications consultant
612-527-1921 (pager)

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