Birth control options while breastfeeding are limited. Many of the hormones required in birth control are transferred to breast milk. Of these hormones, those that are safe during lactation may have an affect on your breast milk supply. Currently, progestin-only contraceptive devices, like the Mirena, are the recommended option for long term birth control for the breastfeeding mother.
Mirena is an intrauterine device (IUD) that is shaped like a 'T' and placed in your uterus for up to five years. During the time that the Mirena is in place, it releases a low dose of progestin. An IUD is a contraceptive device that can only be placed and removed by your health care provider. Contraindications for placement of a Mirena include pregnancy, an anomaly that affects the shape of your uterus, acute pelvic inflammatory disease, postpartum uterine infection or an abnormal Pap smear.
Hormones and Lactation
After your baby is born, the placenta is delivered. Once the placenta is delivered, progesterone levels in the mom's body significantly decrease. This reduction of progesterone is required for the initiation of breast milk secretion.
Hormones in Birth Control
The most common hormones in birth control pills, patches and rings are estrogen and progesterone. Birth control options that contain estrogen are not harmful to babies; however, you should avoid them while breastfeeding because estrogen decreases a woman's milk supply. Progestin is the synthetic form of progesterone. Progestin-only birth control options are available by pill, shot or IUD. While there is no proof that progestin-only birth control negatively affects milk supply, concerns are still present.
Progestin and Milk Supply
For the majority of nursing moms, progestin-only methods of birth control do not cause a decrease in milk supply. However, there are reports of moms stating that they did notice a decrease in their milk supply after starting a progestin-only contraceptive. Unfortunate, there are no absolutes with birth control and breastfeeding.
If you are considering a Mirena while breastfeeding, but concerned about your milk supply, it would be beneficial to try a progestin-only birth control pill for a few months. This will give you a chance to see if you experience any decrease in milk supply with a progestin-only contraceptive, but still allow you the option to discontinue use easily. You can stop taking the progestin pill at any time. Removal of a Mirena requires a doctor's appointment and will not be as convenient. If you find that while taking a progestin-only pill there is no affect on your milk supply, a Mirena would be a viable option.