No information is available on the use of selinexor during breastfeeding. Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy. The manufacturer recommends that mothers should not breastfeed during treatment with selinexor and for one week after the last dose. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[1] Women who receive chemotherapy during pregnancy are more likely to have difficulty nursing their infant.[2]