The majority of tissues in the body grow only in specific areas, but endometrial tissue is an exception. It lines the inside of the uterus and sometimes shows up in areas that are far away from the uterus. This causes the disease “endometriosis”. During your periods, endometrial tissue outside of the uterus builds up before breaking down, as if it were in the uterus. Those who suffer from endometriosis also experience chronic pain. Pills that are progesterone-only prevent menstrual bleeding that makes endometriosis worse.
Every month, endometrial tissue outside and inside the uterus thickens due to female hormones in order for an embryo to implant. If you do not get pregnant, menstrual bleeding occurs as the endometrial tissue is shed. Irritation and even scarring can happen in areas affected by endometriosis, which usually includes the intestines, ovaries, or bladder. More of this irritation and scarring can occur each time the tissue bleeds. Women with this disease often have some degree of infertility that is caused by damage to the fallopian tubes or ovaries. Progesterone pills get in the way of the normal hormone cycle and prevent endometrial tissue from becoming thick and shedding.
Usually progesterone is present in only small amounts in the first half of the menstrual cycle. Progesterone is a female hormone that’s responsible for changing the uterine lining post-ovulation in order for an embryo to implant. After ovulation, levels increase and drop if you don’t get pregnant. When levels drop, the uterine lining breaks down. If you take progesterone each day throughout your menstrual cycle, your ovaries don’t develop an egg in the month because your body is tricked by high progesterone levels, into thinking that it has already made an egg. Taking progesterone continuously means you won’t get your period and bleeding won’t happen in the places impacted by endometriosis.
Certain birth control pills contain what is called “progestin” (artificial progesterone). There isn’t any estrogen in progestin-only pills and since the ovary produces an egg each month just under estrogen’s influence, regular menstrual periods don’t happen. Women often experience spotting in the first three to six months on the pill as their body gets used to hormone levels that are changing.
Approximately 75 percent of women with endometriosis experience an easing of pain with progesterone therapy. Taking progesterone pills does not get rid of damage that has already been caused by endometriosis, but they do help prevent further damage to the tissues. Speak with your doctor about the possible side effects of progesterone supplements.