Hi everyone, welcome to the LactFact podcast, which highlights recent, clinically relevant research, policy statements, and protocols that you, as a practicing lactation professional, should know about. I am your host, Dr Anne Eglash. I am a board-certified family physician and breastfeeding and lactation medicine specialist at the University of Wisconsin School of Medicine and Public Health.

This podcast is written and produced by the nonprofit organization IABLE, which is the Institute for the Advancement of Breastfeeding and Lactation Education. There are no commercial funders for this podcast series.

Today’s Lactfact comes from the recently published 2025 WHO contraceptive medical eligibility criteria. This guideline advises on the safety of contraceptives in the context of medical illness, age, and postpartum and breastfeeding status. The last WHO MEC guidelines were published in 2015.

The Centers for Disease Control, which I am going to now call the CDC, also publishes medical eligibility criteria for contraception and just like the WHO, they categorize contraceptives in 4 categories, 123 or 4.

Contraceptives in category 1 are considered unrestricted and can be used without concern.

Category 2 contraceptives are considered safe because their benefits generally outweigh the theoretical or proven risks. However, I would emphasize that there are identified risks, which I will come back to.

Both Category 1 and Category 2 are colored Green on the CDC chart that summarizes their recommendations, implying that they are both fine to use during lactation.

Category 3 contraceptives are considered concerning and their risks generally outweigh the advantages, so are discouraged but not contraindicated.

Category 4 medications are considered unacceptable in terms of health risk and should not be used.

Both Category 3 and category 4 are colored red on the CDC chart to imply caution.

Contraception during lactation has been a contentious topic because the published research evidence is in conflict with published case reports demonstrating decreased milk production, and in some cases, a complete lack of secretory activation among women, particularly among a few who had progesterone implants placed within the 1st 24 to 48 hours postpartum.

There are also case reports of a drop in milk production when progesterone implants are placed at 4-6 weeks postpartum.

Nevertheless, These progesterone contraceptives are labeled green because they are either category one or category 2 during lactation.

So Let’s review the updated World Health Organization medical eligibility criteria for birth control during lactation:

Let’s start with the immediate pp period-

All estrogen-containing contraceptives, whether oral, injectable, or vaginal ring preparations are considered category 4, or contraindicated, until 6 weeks postpartum. This is also true for non-breastfeeding women because of the risk of blood clots within the first six weeks after birth.

They recommend that the progesterone only contraceptives which include the progesterone only pill, depo medroxyprogesterone acetate, AKA Depo Provera, and the levonorgestrel or etonogestrel implants that are typically placed under the skin in the inner arm are category 2. This means that the benefits are considered to outweigh theoretical or real risks to lactation. This is the major change from 2015 to 2025. In 2015, the injectable progesterone Depo was categorized as Level 3, with the perceived risks being greater than the benefits because of the risk of insufficient milk production, and the fact that it is not reversible, since it cannot be removed like the progesterone implants or IUDs.

The WHO admits that the quality of the evidence for these recommendations ranges from low to very low.

IUDs are also used within the first 48 hours postpartum and the copper IUD is considered to be category 1, so no concern regarding lactation. The progesterone IUD’s are considered category 2, so although acceptable, they have a risk of impacting milk production. As in 2015 they recommend avoiding either form of IUD between 48 hours and four weeks postpartum because of the risk of expulsion.

After four weeks postpartum the progesterone and copper IUDs are considered category one.

Let’s move on to birth control beyond the immediate postpartum. The WHO has maintained their 2015 recommendations that combined hormonal contraceptives containing estrogen are category 3 should be avoided until six months due to the risk of dropping milk production. After six months they are category 2 meaning that there is still a theoretical risk although the benefit is considered to outweigh that risk.

The progesterone contraceptives are considered category 1 after 6 weeks pp. This means that the POP, depo provera, the progesterone IUD and progesterone implants are considered to have no risk to milk production. This is a good example of where our clinical experiences diverge from these recommendations .

In terms of emergency contraception the World Health Organization Identifies 3 options, combined oral contraception, levonorgestrel tablets or ulipristal acetate. Both the combined oral contraceptive and the levonogestrel emergency contraceptive agents are considered category 1 because they are typically taken as just 2 doses. Ulipristal acetate is considered category 2 because the WHO recommends expressing and dumping milk for a week after taking it, to avoid infant exposure. However, the US FDA no longer requires withholding breastfeeding after taking it because the milk levels are low.

The major update in the 2025 WHO MEC compared to 2015 is switching Depo Provera from a category 3 to category 2 immediately postpartum.

The CDC, on the other hand, has always considered Depo Provera to be level 2 early postpartum, so now the WHO is more inline with the CDC.

There are a few remaining major differences between the CDC and World Health Organization medical eligibility criteria.

1. The CDC switches a few of the progesterones from category 2 immediately pp to category 1 at 21 days postpartum whereas the WHO makes this switch from category 2 to category 1 at 6 weeks.

2. The most significant difference is the category of combined hormonal contraception under six months pp. The CDC recommends that after one month postpartum the combined hormonal contraceptives are category 2, so therefore considered reasonably safe in terms of milk production. However the World Health Organization recommends that combined hormonal contraceptives remain as category 3 between 6 weeks and 6 months postpartum, and then are category 2 after 6 months.

Here’s my opinion- We have to remember that a 2 is not a 1. The CDC’s downloadable MEC chart uses a green color, as I mentioned, for both category 1 and 2 , and a red color for categories 3 and 4. The green color is a ‘good to go’ signal, even though these category 2 contraceptives, such as progesterone implants and Depo, can seriously impact lactation.

The same problem occurs with combined hormonal contraception after one month because they are considered category 2 in the United states. Again many physicians do not understand why they are category 2 vs category 1. They see the green color on the chart, so they don’t worry about risks.

My suggestion is that the CDC needs to use a different color for category 2 contraceptives, such as yellow as the international signal for caution.

We need more research to understand who is most impacted by hormonal contraception during lactation.

The World Health Organization recognizes that the studies on contraception during lactation do not include vulnerable populations such as women with premature infants or women with other risk factors for low milk production such as older age, insulin resistance or gestational hypertension.

And sadly I would say that when I have talked to obstetrician gynecologists about the categorization of these contraceptives during lactation particularly category 2 they generally had no idea that they should be counseling patients about the theoretical risks to lactation.

If we’re going to make significant changes to enable women and other lactating parents to have agency to balance contraception and lactation, physicians and other providers should be required to have lactation education so that they can provide evidence based shared decision making with their patients. Otherwise patients are at risk of experiencing unintended loss of milk production, which unfortunately, to this day, is still a real phenomenon in my breastfeeding medicine practice.

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