Birth Defect Risk Linked to Antibiotics Like Bactrim and Macrobid

A new study has found that certain types of antibiotics, such as Bactim, Thiosulfil Forte, Furadantin and Macrobid, could increase the risk of birth defects when used by pregnant women.

The study, published in the November issue Archives of Pediatrics and Adolescent Medicine, suggests that there is an increased risk of birth defects from sulfa drugs (sold under the brand names Bactrim and Thiosulfil Forte) and nitrofurantoins (sold as Furadantin and Macrobid). The drugs are often used to treat urinary tract infections, however, the most commonly used antibiotics during pregnancy, penicillins, were not found to have the same risk for unborn children.

The antibiotic birth defects study is the first large investigation of the risks of antibiotic use by pregnant women, researchers said. Doctors looked at about 18,000 women, including more than 13,000 women who gave birth to children with birth defects, and 5,000 women from the same geographic regions who gave birth to healthy babies.

Focusing on antibiotics used for urinary tract infections, the researchers interviewed the women about their antibiotic use during the months before conception and through the first trimester of their pregnancy. Researchers warned that some of their data is based on the subjects’ memories, which can be faulty. At least a third of the women interviewed could not remember which antibiotics they were prescribed.

Researchers found that sulfa drugs were linked to six different types of birth defects, including an increase in rare brain problems, heart defects, and stunted limbs. Nitrofurantoins were linked to four different types of birth defects, including cleft palate and heart problems.

However, the scientists warned that even with the increased risks, the chances of birth defects from antibiotics were very rare. The study authors said that they believe the risk to the baby from untreated infection was far greater, and suggested that pregnant women who need to take antibiotics discuss their options with their doctor.

Researchers said more studies were needed before a determination could be made on which antibiotics were safe for pregnant women to take and which ones were not.