Study finds link with birth defects, common antibiotics

CHICAGO (AP) — Researchers studying antibiotics in pregnancy have found a surprising link between common drugs used to treat urinary infections and birth defects. Reassuringly, the most-used antibiotics in early pregnancy — penicillins — appear to be the safest.

Bacterial infections themselves can cause problems for the fetus if left unchecked, experts said, so pregnant women shouldn’t avoid antibiotics entirely. Instead, women should discuss antibiotics choices with their doctors.

The new study is the first large analysis of antibiotic use in pregnancy. It found that mothers of babies with birth defects were more likely than mothers with healthy babies to report taking two types of antibiotics during pregnancy: sulfa drugs (brand names include Thiosulfil Forte and Bactrim) and urinary germicides called nitrofurantoins (brand names include Furadantin and Macrobid).

It was the first time an association had been seen between urinary-tract treatments and birth defects, said lead author Krista Crider, a geneticist with the Centers for Disease Control and Prevention, which funded the research.

Used for many decades, the antibiotics in question predate the Food and Drug Administration and its requirements for rigorous safety testing. The FDA now grades all drugs for safety to the fetus based on available research, but rigorous studies are so lacking in many cases, that no antibiotics get the highest grade of “A.”