Pregnancy and Lactation: Erythromycins cross the placenta, resulting in low fetal plasma concentrations (5 to 20% of maternal plasma concentrations). Erythromycin estolate has been associated with an increased risk of reversible, subclinical hepatotoxicity in approximately 10% of pregnant women; its use during pregnancy is not recommended. However, problems with other Erythromycins have not been documented.
There was no evidence of teratogenicity or any other adverse effect on reproduction in female rats fed Erythromycin base (up to 0.25% of their diet) prior to and during mating, during gestation, and through weaning of 2 successive litters.
Erythromycins are distributed into breast milk. However, problems in humans have not been documented.