Some hormonal contraceptives contain only progesterone. These formulations may be recommended for women who are breastfeeding, because they have less effect on milk production than combined hormonal contraceptives. They may also be recommended for women who need to avoid estrogen for other reasons (e.g., because of a history of blood clots).
Progesterone-only contraception works by changing the body’s hormonal balance. This often prevents ovulation. It also alters the consistency of the mucus produced by the cervix, endometrium, and Fallopian tubes in a way that inhibits conception.
Some women continue to menstruate while taking this type of pill, others stop bleeding entirely (amenorrhea).
There are several different formulations of progesterone-only contraceptive pills (the “minipill” or “POP”). The pills are taken daily, without a break.
Progesterone is also available as an injection administered every three months (Depo Provera) and as an implant inserted under the skin of the upper arm for up to three years (Implanon, Nexplanon). There are also IUDs that releases progesterone, discussed here. In some countries (not including the US or Israel), progesterone is available as a vaginal ring.
The progesterone-only pill is approximately 91% effective with typical use. The implant is over 99% effective, and the injection about 94% effective.
About 40-70% of women experience irregular bleeding during the first three months with progesterone-only contraception. For most women, this bleeding diminishes after a few months, although it may not resolve as quickly as breakthrough bleeding on combined hormonal contraceptives.
Taking the pill at the same time each day may help reduce the likelihood of spotting (and is important in maintaining the maximum contraceptive effect). A woman who nevertheless experiences continued staining beyond the initial adjustment should discuss possible solutions with her physician. They may suggest changing the dosage, or the formulation (if available), or other strategies.
While many women will reach a point where staining stops or becomes manageable, sometimes it will be necessary to explore alternative methods of contraception. (Combined hormonal contraceptives are safe for use when breastfeeding, although they can affect milk supply. See here for more on this topic.)
Other potential side effects include mood changes (especially depression) and weight gain.
Injections and implants
Both injections and implants are more likely to cause irregular spotting or bleeding than other hormonal methods of contraception. An implant can be removed only with a medical procedure and is generally a less-preferred option. With injections, bleeding cannot easily be resolved, and the contraceptive effect is also irreversible for at least three months. Therefore, injections are generally not recommended for observant women.
Progesterone-only contraception is considered a halachically permissible method when contraception is allowed. It has a number of halachic advantages: Its effect is temporary and reversible, it does not destroy sperm, and it does not interfere in any way with the normal course of marital relations. On the other hand, the irregular bleeding and spotting associated with progesterone-only contraception can raise halachic questions.
Because of the risk of bleeding, it is important to review the laws of stains (ketamim) before starting progesterone-only contraception. As always, one should wear colored underwear when not in niddah, take precautions with toilet paper, and ask halachic questions rather than assuming that a stain has made one niddah. If breakthrough bleeding occurs during the shivah neki’im (seven clean days), one can ask a halachic question about reducing the number of bedikot.
Couples should be prepared for the possibility of a difficult beginning, and should be prepared to test the method for several months before abandoning it.
Postpartum, a woman may wish to consult her physician about waiting until after her first immersion to begin the pills, and using short-term contraception such as spermicide in the interim. In this way, she can avoid the more difficult halachic questions that arise with staining during the shivah neki’im.
This article was updated in April 2022.