Ophthalmia neonatorum is a newborn eye infection and in the United States occurs in 1-2% of newborns. This infection can be caused by sexually transmitted infections, viruses, and bacteria. Administering erythromycin eye ointment to newborns is standard procedure in the United States to prevent ophthalmia neonatorum. As with any intervention, there are pros and cons to consider. This article examines the evidence on the efficacy and safety of erythromycin eye ointment so you can make an informed choice for your baby.