Will breastfeeding keep my spouse from getting pregnant?
When your spouse breastfeeds, her ovaries can stop releasing eggs, making it harder for her to get pregnant. Her periods can also stop. But according to the U.S. Department of Health & Human Services, there are no guarantees that she will not get pregnant while she is nursing.
The only way to make sure pregnancy does not occur is to use a method of birth control. If you and your spouse want to use a birth control pill while breastfeeding, the safest type is the "mini-pill." However, you should talk with your doctor or nurse about what birth control method is best to use while breastfeeding.