If you take the contraceptive pill, there is no known adverse effect on your baby if you are breastfeeding. Sometimes the pill can reduce the amount of breast milk delivered to the baby, but this is not significant if you have a well established breastfeeding program. Your periods will be light while on the pill. If you want to avoid a period while on the pill you can skip the placebo week (after 3 weeks) and start on a new pack of pills.