A contraceptive that only contains the hormone progestin is safe to use while breastfeeding. BabyCenter states that contraceptives that also include estrogen should be avoided because this hormone may cause a decrease in milk supply.
Birth control pills that contain a low dose of progestin, also known as mini-pills, help prevent pregnancy by thickening cervical mucus so sperm cannot pass. It's important to take the mini-pill at the same time every day to maintain its effectiveness.
Other forms of acceptable contraceptives for use while breastfeeding include birth control shots such as Depo-Provera, flexible progestin-delivering rods that are implanted into the upper arm, and IUDs. Barrier methods such as condoms and cervical caps are also suitable for this period.