Effectiveness of the Progesterone-Only Birth Control Pill for Breastfeeding and Non-Breastfeeding Women
by Anne Eglash MD, IBCLC, FABM
Most physicians or other providers who work with postpartum women identify that the progesterone-only birth control pill (POP), aka the mini pill, is an appropriate birth control option because it is less likely to decrease milk production as compared to a combination oral contraceptive with estrogen (COC). However, according to the Centers for Disease Control Medical Eligibility Criteria, the COC is rated as generally safe for breastfeeding women starting at 6 weeks postpartum, with its advantage generally outweighing theoretical or proven risks.
In contrast, the World Health Organization medical eligibility criteria recommends not using the COC until 6 months for breastfeeding women, with a recommendation for follow up as needed.
Physicians often recommend a switch from the POP to the COC at some point during lactation to decrease the risk of pregnancy. The question is what do we know about the risk of pregnancy for breastfeeding women on the POP, and does it differ from non-breastfeeding women? Does it differ from the COC?
According to the authors of this week’s systematic review, the POP is now available without a prescription in UK pharmacies, and there is an initiative to submit an application to the US Food and Drug Administration to allow the over-the-counter sale of the POP. Therefore, the goal of the review was to explore the rate of pregnancy on the POP for breastfeeding and non-breastfeeding women, with anticipation that it may be available at some point in US pharmacies without a prescription.
The review identified 6 studies of 3184 women who were not breastfeeding, and 7 studies included 5445 women who were breastfeeding at some time. None of the 7 trials defined the degree or duration of breastfeeding.
Overall, this review found that the rate of pregnancy on the POP did not differ significantly between breastfeeding and non-breastfeeding women.
And, although the authors did not compare the rate of pregnancy with the POP vs the COC, they state in their introduction that research has not shown a difference in pregnancy rates between COC and POP users.
- For every 100 non-breastfeeding women, 2.2 became pregnant each year.
- For every 100 non-breastfeeding women, 5 became pregnant each year.
- For every 100 breastfeeding women, 0-4.9 became pregnant each year.
- For every 100 breastfeeding women 5-8% became pregnant each year.
See the Answer
Abstract
Objectives
To review published data on the effectiveness of a progestogen-only pill containing norgestrel 75 μg/day which should be under consideration by the FDA in 2022 for sale over the counter in the US.
Study Design
A literature search in MEDLINE, EMBASE, and COCHRANE REVIEWS using specified search terms and adding related cross-references.
Results
We identified a total of thirteen relevant studies of women using norgestrel 75 μg/day. None were reported with the rigor characteristic of trial reporting today. Nevertheless, six studies provided data on 3,184 women who were not breastfeeding, followed for over 35,000 months and reported a range of overall failure rates during typical use of norgestrel 75 μg/day from 0 to 2.4/hundred woman-years giving an aggregate Pearl Index of 2.2. Seven additional studies involved 5,445 women some of whom were breastfeeding for at least part of the period of follow-up. More than 36,000 months of use yielded 12-month life table cumulative pregnancy rates for norgestrel 75 μg/day ranging from 0 to 3.4. We were unable to calculate an aggregate Pearl Index for the breastfeeding studies because of lack of crucial data.
Conclusions
The data support that norgestrel 75 μg/day is highly effective in clinical use, with similar estimates of failure in breastfeeding and non-breastfeeding women, providing support to the case for approval without the need to see a healthcare provider.
In this study, the differences in pregnancy rates for breastfeeding vs non-breastfeeding women on the POP were not considered significantly different.
They state in their introduction that the failure rate of the POP is the same as the COC, with 9% of US women experiencing pregnancy in the first year of use if not used perfectly, and 0.3% with perfect use for either type of contraceptive tablet.
Based on this statement, breastfeeding women should not be coaxed into switching to the COC, unless they have an interest in lowering their milk production.
The authors discuss that the POP is considered a very safe form of birth control. Therefore, it would be a low risk medication for over-the-counter use, and certainly more effective than the barrier methods currently available over the counter, including condoms, the vaginal sponge, or spermicides.
The Centers for Disease Control Medical Eligibility Criteria list only 4 relative or strict contraindications to the POP, including breast cancer, liver cirrhosis, non-cancerous liver tumors, and ischemic heart disease.
If and when the POP is available over the counter in US pharmacies, it would be reasonable to advise breastfeeding women that the POP is a safe and effective form of contraception.
Nikki Lee
While the review indicates that the POP pill is safe and effective, there is no mention in the study of any impact on lactation or milk supply.
The absence of that important information, in view of the experiences of many mothers over my career of nearly 50 years in the field of breastfeeding management and lactation education, makes me reluctant to promote the POP.
That said, I much prefer the POP to progestin-only IUDs or implants, or the depot-provera shot because if milk supply is negatively impacted by the POP, it is easy for the mother to stop taking the pill.
I also like the idea of having a strong contraceptive method available in the OTC route, especially in view of the US’s steady assault on reproductive rights.
Victoria Anzalone
If POP can decrease milk production in a breastfeeding woman, why should POP be promoted? What about Natural Family Planning, which, if practiced corrrectly, is 98% effective last time I looked. Also, why is it ok to subject breastfeeding babies to unnecessary hormonal drugs through their mother’s breastmilk?
What about Lactation Amenhorrea Method? In my experience, women are not given information regarding Natural Family Planning and/or LAM.
IABLE
I have to say that over time, I have been less impressed with LAM effectiveness. Most of the studies have been done in countries where women are not as supercharged nutritionally as they are in the USA. I have been surprised at the # of women I see who resume menses in the first few months despite exclusively breastfeeding day and night, who have not gone back to work and are not pumping and bottle feeding. Whether this is related to not bedsharing, or the effect of green smoothies/nutritionally packed diets, it is hard to say, but we need contemporary research on LAM to determine if the same outcomes apply to high resource populations. My experience over 33 years of practicing family and breastfeeding medicine is that the POP and the IUD are the most efficacious contraceptive options for lactating women with the least risk of pregnancy and drop in milk production. I rarely see a drop in milk production on POP, as compared to norgestrel or depo medroxyprogesterone, and that may be due to my ability to counsel women appropriately. Unfortunately we cannot rely on good research evidence to substantiate our observations because it just is not available. I don’t think it is fair to assume that the POP has no legitimate role as a good contraceptive option for lactating women, and all lactating women should not be relegated to less effective contraceptive options. Women at highest risk for a drop in milk production from hormonal contraceptives are likely those who already struggle with low production, have premature infants, or have multiples, as per the ABM guidelines on contraception and breastfeeding. Lactating women who have a healthy milk production are much less likely to have a drop in milk production from the POP.