Methoxy polyethylene glycol-epoetin beta is a synthetic form of erythropoietin that slowly releases the active drug, epoetin beta (recombinant human erythropoietin). Erythropoietin is a normal component of human milk. The excretion of exogenous methoxy polyethylene glycol-epoetin beta in breastmilk has not been studied; although the similar drug epoetin alfa has been studied and is considered to be acceptable during breastfeeding. Since no information is available on its use during breastfeeding, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.