PERIODS & CONTRACEPTIVES
Some women start menstruating as early as six weeks after delivery. But in some women who breast-feed, menstruation is usually delayed longer than that sometimes for as much as 18 months. Menstruation stops because ovulation (egg production) stops. And a woman who does not ovulate does not get pregnant.
So, breast-feeding, because it delays ovulation, helps to space children. But this effect wears off, and menstruation often starts again, long before you stop breast-feeding. Once menstruation starts after the delivery, you are as fertile as before. But the first ovulation occurs two weeks before the periods start so you can conceive before menstruation reappears. So breast-feeding is not a reliable way for you to prevent pregnancy even if you haven't started menstruating. There is no way of knowing exactly when you will begin to ovulate again whether it will be two, six, twelve, or eighteen months. You should therefore use some form of contraception unless you want another child in a years time.