Most methods of contraception that women use are not considered to be harmful to their breastfed children, but some forms of contraceptives can be very harmful to milk supply.
Estrogen-containing contraceptives have been linked to low milk supply and a shorter duration of breastfeeding even when started when baby is older, after milk supply is well established. Not all mothers who take contraceptives containing estrogen will experience a low milk supply, but these unaffected mothers appear to be a very small minority. Thomas Hale, PhD (author of Medications and Mothers’ Milk) notes, “Mothers who have problems with milk production and those who are breastfeeding an older child (one year old or more) should be especially cautious.”
Progestin-only contraceptives are the preferred choice for breastfeeding mothers when something hormonal is desired or necessary.
Progestin-only contraceptives come in several different forms:
- progestin-only pill (POP) also called the “mini-pill”
- birth control injection (Depo-Provera)
- progesterone-releasing IUD (Mirena, Skyla)
- birth control implant (Implanon, Nexplanon)
For most mothers, progestin-only forms of contraception do not cause problems with milk supply if started after the 6th-8th week postpartum and if given at normal doses. However, there are many reports (most anecdotal but nevertheless worth paying attention to) that some women do experience supply problems with these pills, so if you choose this method you still need to proceed with some caution.
If you’re interested in one of the longer lasting progestin-only forms of birth control (the Depo-Provera injection lasts at least 12 weeks, but effects may be seen up to a year; the progesterone-releasing IUDs and implant last 3-5 years), it is recommended that you do a trial of progestin-only pills (mini-pill) for a month or more before deciding on the longer-term form of birth control. If you find that you are among the women whose supply drops significantly due to progestin-only birth control, you can simply discontinue the pills – rather than struggling with low milk supply for several months until the injection wears off or you get the implant or IUD removed.
Do note that the progesterone-releasing IUD delivers its hormone directly to the lining of the uterus, which only leads to a slight increase in progesterone levels in the blood stream (much lower than that found with the progesterone-only pill). As a result, there is much less chance of side effects from the progesterone than from the injection or mini-pill.
Milk composition: At higher doses than normal this type of pill can affect the content of breastmilk. At these higher doses it has been shown to decrease the protein/nitrogen and lactose content of the milk. At regular doses, this does not seem to be as likely.
Morning-after pills should be used only as a last resort (whether you are breastfeeding or not).
There are currently two types of products on the market packaged specifically as “morning-after pills:”
- a combination pill containing estrogen and progestin
- a progestin-only pill
Milk supply: Estrogen, in particular, has been linked to low milk supply in nursing mums. There may be a slight drop in milk supply a few days after taking the morning-after pill, but milk levels should rebound thereafter.
Safety: The morning after pill is considered compatible with breastfeeding, but should only be used rarely. Not the first choice for routine birth control, it should be used only as a last resort (whether breastfeeding or not). Both progestin and estrogen are considered compatible with breastfeeding by the AAP.
Milk supply: As noted above, hormonal birth control pills (particularly those containing estrogen) have the potential to decrease milk supply, sometimes dramatically.
Effects on baby: There have been no adverse reports of side effects to the baby. Children whose mothers used hormonal birth control while nursing have been followed as late as 17 years of age. The exception to this is the very young baby – less than 6 weeks old. There may be some concern about the baby’s immature liver being able to metabolize the hormones passed through the milk well enough.
Any hormonal birth control may cause fussiness in the baby (not reported in the literature but often anecdotally by mothers). This may be due to the hormones causing a minimal decrease in the protein/nitrogen/lactose content of the milk. Some mothers have reported marked improvement in their baby’s degree of fussiness once they come off hormonal birth control.
Effects on mother: If you had gestational diabetes during pregnancy, talk to your doctor about the safety of using the mini-pill while breastfeeding. A 1998 study conducted at the University of Southern California School of Medicine in Los Angeles (Kjos SL, et al. Contraception and the risk of type 2 diabetes mellitus in Latina women with prior gestational diabetes mellitus. JAMA. 1998 Aug 12;280(6):533-8.) indicated that for certain women, taking the mini-pill while breastfeeding may increase the risk of chronic, non-insulin-dependent diabetes. This study of more than 900 Latinas found that those who had been diagnosed with gestational diabetes and then took mini-pills while breastfeeding had an almost threefold risk of developing type II diabetes within a year, compared with those who used different contraception. This study concentrated on Hispanic women, and thus it is not clear whether the results can be applied to all ethnic groups. Other, smaller studies on the mini-pill did not show any increased rates of diabetes, so more research in needed on this subject.
- Use any hormonal type of birth control with caution (particularly the forms that contain estrogen).
- Use as low a dose as possible.
- If you experience supply problems (or if baby’s weight gain slows more than expected or stops) and are using any type of hormonal birth control, it’s a good idea to discontinue using it for a time and see if your supply rebounds as a result
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