Breastfeeding can be used as birth control!

After a woman has a baby, she can remain free of the risk of pregnancy so long as she breastfeeds her child. This happens because of the amount of hormones in her body. The act of breastfeeding naturally changes a woman’s hormones to not allow ovulation.

If a woman can’t ovulate, she can’t become pregnant. This method is effective for up to six months and can work better than mainstream contraception.

(Source)