To bury the myth once and for all: women who breastfeed are not necessarily infertile and can, in fact, get pregnant.
However, women who are breastfeeding have anovulatory cycles over the course of several months. This means that during breastfeeding, no oocytes are maturing and therefore they are infertile. This does not extend over the entire breastfeeding period and depends on factors such as the woman’s age and the frequency and duration of breastfeeding. Generally speaking, the more frequent and longer the episodes of breastfeeding are, the longer the period of anovulation and thus infertility persists.
If the woman has been breastfeeding for more than six months and the breastfeeding periods are not regular and sufficiently consistent, then there is a possibility of becoming pregnant. This can also be the case even if menstruation has not yet occurred, as postpartum ovulation can take place without previous menstruation, which actually is relatively common.