What Would Happen If A Man Took Birth Control?

To prevent pregnancy, birth control pills contain female hormones — estrogen and progestin, or just progestin alone. The pill​​ that contains both hormones prevents pregnancy by blocking ovulation from occurring and by changing the uterine lining to make it inhospitable to a fertilized egg (via Medline Plus). Pills that have only progestin prevent pregnancy mainly by thickening the cervical mucus, which decreases the ability of sperm to reach and fertilize an egg (via American College of Obstetricians and Gynecologists). 

Men who were born male don't have a uterus, cervix, or ovaries, so the pill would have nothing to act on, right? Well, not exactly. The effect of a man taking a birth control pill depends on a few factors. If a man were to take one pill accidentally or intentionally, the result would be different than if he were to take a pill every day for a period of time. In addition, a transgender man might experience different effects than a cisgender man.

A birth control pill is lying on the counter next to a man's vitamin or decongestant, and he absent-mindedly swallows the birth control pill instead of his intended pill. Or maybe a curious guy downs a pill just to see the result. So what would be the result? Nothing really.

A single birth control pill or even a couple of them don't contain enough female hormones to do anything to a male body (per Planned Parenthood). A man who mistakenly swallows the pill doesn't have to worry about low sperm production, impotence, or growing breasts overnight. A man who takes birth control consistently, however, may undergo some physical changes.

According to Science Focus, if the pill he takes contains both estrogen and progestin, over time it will make his body appear more feminine, including increased breast tissue and wider hips. If the pill contains only progestin, both his sperm production and sex drive would be reduced. Cisgender men should keep in mind that even though regular use of the pill produces a slight feminization of the body and has an effect on fertility, there are not enough female hormones in it to stop sperm production and prevent pregnancy in a partner (via Greatist). The pill shouldn't be used as contraception in this case.

If a transgender man has not had bottom surgery and thus has a uterus and ovaries, he can become pregnant. Therefore, as Greatest explained, "taking birth control can help control monthly flows and prevent pregnancy."

Pregnancy can also occur while undergoing masculinizing hormone therapy (MHT). MHT includes the use of testosterone to suppress the menstrual cycle and decrease estrogen production (via Mayo Clinic). Although MHT contains testosterone, it may not consistently block ovulation even if menstruation stops, and shouldn't be depended on to prevent pregnancy (per Contraception Journal). 

Trans men have a few options for contraception. The pill with just progestin may be one, although how it interacts with MHT isn't clear, according to research published in the Contraception Journal. It's recommended that estrogen-containing contraceptives — such as the vaginal ring, the pill, and the patch — be avoided, as there aren't a lot of data on the potential risks and side effects of taking them while undergoing MHT.