In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to erythromycin may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is erythromycin?

Erythromycin is an antibiotic. Some common brand names include Eryc®, E.E.S.®, E-mycin® and Ery-Tab®. It can be taken by mouth to treat several infections, particularly those of the skin, upper respiratory tract and pelvis. It can also be used in topical forms for treatment of skin conditions and as an ointment for eye infections.

Can taking erythromycin in the first trimester cause a miscarriage?

There are no studies looking specifically to see if exposure to erythromycin taken in the first trimester would increase the risk for having a miscarriage. However, no studies that have looked at the risk for birth defects have noted a higher rate of miscarriage.

Can taking erythromycin use in the first trimester cause a birth defect?

Not likely. A couple of studies have suggested that exposure to erythromycin in the first trimester might be associated with a small increased chance for heart defects. This association has not been confirmed. In fact, the majority of studies have not found an increased chance for birth defects above the background risk when erythromycin is taken in pregnancy.

Can erythromycin cause other pregnancy complications?

Some reports suggest that exposure to erythromycin during pregnancy might be associated with an increased chance of pyloric stenosis (a narrowing of the opening from the stomach to the small intestines). Other studies have not supported this finding. In addition, the majority of studies have not shown an increased chance for adverse outcomes when erythromycin in used later in pregnancy.

Can I take erythromycin when I am breastfeeding?

You should not stop taking your medication without talking to your health care provider. Small amounts of erythromycin can get into breast milk. In one study, a higher chance of pyloric stenosis was seen in infants whose breastfeeding mothers were prescribed erythromycin at the time of birth or within ninety days after. While we know the mothers were prescribed the medication we do not know if it was actually taken. A more controlled study did not support an association between exposure to erythromycin while breastfeeding and a higher chance for pyloric stenosis. Presently, short-term use of erythromycin is generally considered to be compatible with breastfeeding. As with exposure to any antibiotic, the breastfed infant should be closely observed for adverse effects such as diarrhea.

What if the father of the baby takes erythromycin?

There are no studies looking at possible risks to a pregnancy when the father takes erythromycin. In general, medications that the father takes do not increase the risk to a pregnancy. For more information, please see the OTIS factsheet on Paternal Exposures at:


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