This depends on whether you are breastfeeding or not. If you are not breastfeeding, your first period will occur about two months after childbirth. However, there is no way to know when you begin to ovulate again - 90 percent of women will not ovulate before their first period. So contraception is essential if you have sex soon after childbirth.
If you are breastfeeding, your period may resume at any time from about two months after childbirth. Some women only get their period back once they stop breastfeeding. It is important to know that breastfeeding is not a form of contraception. It is the sensation of the baby sucking that send a message to the brain to suppress the hormone that stimulates ovulation.