Clinical minute: Effects of birth control on lactation

What providers need to know when counseling patients about their birth control options and achieving their lactation* goals

by Elizabeth Elsagga, DO, CCL

published 04/18/22

The Scenario:

AE is interested in starting birth control four weeks after having their first child. They are providing human milk via breastfeeding but need to supplement formula one to two bottles a day because of “not having enough milk.” Prior to pregnancy they were happy with a hormonal implant but is unsure if this method is safe while producing milk.

How would you counsel AE about their birth control choices today?

Is birth control safe during lactation?

Hormonal birth control has long been considered safe to use during lactation for both parents and infants. Safety can be separated into parent safety and infant safety. Parent safety includes risk to the health of the birthing person, including high blood pressure and blood clots, the likelihood which are elevated in the postpartum time period. Infant safety includes potential for harm from exposure to hormonal birth control (considered low) as well as losing the benefit of exclusive feeding with human milk. However, individual decisions about birth control go beyond safety and include considerations of how birth control can affect the milk supply.

Parent safety

Birth control safety in the postpartum period depends on the type of hormonal birth control used, how long it’s been since delivery, if someone is lactating, and an individual’s risk of venous thromboembolism (VTE). However, by 42 days postpartum, all birth control methods can be used by people who are lactating without restrictions according to the U.S. Medical Eligibility Criteria for Contraceptive Use (as long as they don’t have other contraindications).

Progestin-only options, including progestin-only pill, implant, shot, and hormonal IUD, can all be started immediately postpartum and have less of a risk in decreasing milk production, however counseling should include that there is a risk of decreased supply and how to quickly change methods should this occur. All non-hormonal and behavioral methods are safe to use in the postpartum period and offer the least risk of impacting milk supply.

Infant safety

All birth control methods are safe to use while lactating in terms of infant safety. No progesterone only method has been noted to show differences in growth or development when compared with other babies whose parent was not taking a hormonal birth control method. Use of estrogen-containing methods are also safe as the exposure is low because estrogens are not excreted into milk at a high level. There are case reports of neonatal breast development with combination pill use, however that subsides when pills are stopped and no differences in growth of development were noted. For more information about the safety of individual methods (and other medications), the National Center for Biotechnology Information has a free online database.

What are the consequences of hormones while lactating?

Although all methods of birth control are safe from an exposure standpoint, a reduction in the amount of milk can lead to an increased need for supplementation and eventually early weaning if not recognized.

Progesterone and estrogen are important hormones in pregnancy and lactation. An increase in these hormones after delivery can both impede lactogenesis II, which is needed for the production of milk after delivery, and limit the amount of milk that is produced. However, there is variability between individuals in the amount that exogenous estrogen and progestin decrease milk supply.

While all estrogen-containing methods, such as combination pills, patches, and rings, will cause a decrease in the amount of milk produced, combination pills are the most likely to cause a decrease in milk production. Milk production declines with combination pills may be significant enough that they can be utilized when someone wants to stop production of milk altogether. Some progestin-only methods have also been documented to decrease milk supply, with the shot having the greatest risk for milk supply reduction of all the progestin-only methods and the implant is slightly more likely than a hormonal IUD to cause a decrease in the amount of milk produced. However, the studies looking at these effects have very small sample sizes and are limited.

What about LAM (lactational amenorrhea method)?

Lactation, in and of itself, can be highly effective birth control. LAM is 98% effective at preventing pregnancy if the following three criteria are met:

  • No return of menses.
  • All infant nutrition is from human milk directly (versus expressed milk) with no more than four hours between feedings, including overnight.
  • Infant is less than six months of age.

However, as soon as any one of these criteria are not met (for example, AE in this scenario), particularly if milk removal is spaced out overnight, then LAM quickly loses its efficacy. Education on LAM should include information on how to follow up for alternative birth control options, including hormonal and non-hormonal options, in the first six months if any of these criteria are no longer met.

Back to our scenario – Do you offer AE another implant?

It depends on what they want! Although the implant is safe during lactation, it may affect the amount of milk AE produces.

It is important to ask questions to understand AE’s birth control preferences as well as their long- and short-term goals for lactation. Counseling should include information on the safety of all methods and consideration of how starting an implant today could impact milk production and how that may impact long-term breastfeeding goals. However, if the supplementation is going well and AE feels the most important aspect of today’s visit is avoiding pregnancy, an implant may be the best option. What is most important is giving AE the best information so that they can choose the method that’s right for them based on both contraceptive needs and their goals for lactation.

*We know that words matter, and we aim to use the most inclusive language on Bedsider Providers. In this article, we are using lactation to include anyone who is giving human milk through direct chest or breastfeeding as well as those who are giving expressed milk.

Dr. Elsagga is an OB/GYN and specializes in Breastfeeding Medicine. She practices in upstate New York.
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