The progestins of contraceptive injections and implants can cause depression, weight gain, and irregular menstrual bleeding.
Side effects occur because: 1) progestins are not progesterone, and 2) progestins at that dose can suppress ovulation and cause anovulatory bleeding. Keep reading to learn the difference between a real period, an anovulatory bleed, and a pill-bleed.
Progestins are not progesterone
Progesterone is a beneficial hormone for mood, hair, thyroid, bones, skin, metabolism, and immune function. Unfortunately, there’s no progesterone in any type of hormonal birth control. Instead, contraceptive injections and implants contain the progestin steroid drugs medroxyprogesterone acetate, levonorgestrel, or etonogestrel, many of which have a high androgen index and so can cause weight gain.
Medroxyprogesterone acetate is the progestin in the Depo-Provera injection. It suppresses ovarian function so strongly that it can cause bone loss due to estrogen deficiency. Medroxyprogesterone acetate can also cause insulin resistance and unstoppable weight gain.
Levonorgestrel is the progestin in Norplant and Jadelle. It’s derived from testosterone and so can cause androgenic (male hormone) side effects such as acne, hair loss, and weight gain. Levonorgestrel can increase the risk of ovarian cysts and has been linked with anxiety and depression.
Etonogestrel is the progestin in Nexplanon or Implanon. It can increase the risk of ovarian cysts and mood problems but is less androgenic (testosterone-like) than levonorgestrel so is less likely to cause acne, hair loss, and weight gain.
Anovulatory bleeding from progestin-only birth control
A real period is a withdrawal bleed from the body’s own progesterone. It occurs at the end of an ovulatory menstrual cycle, which is a menstrual cycle in which ovulation occurred and progesterone was made. The timing of a real period is about the healthy functioning of the ovaries.
👉🏽Tip: Ovulation is the main event of a menstrual cycle.
An anovulatory bleed is the bleed that happens when the uterine lining has been exposed to estrogen, but not progesterone. Anovulatory bleeds occur with perimenopause, PCOS, and progestin-only methods of birth control.
👉🏽Tip: The only type of hormonal birth that permits natural ovulatory menstrual cycles is the hormonal IUD.
Finally, a pill-bleed is a withdrawal bleed from the contraceptive drugs ethinylestradiol and progestin. The timing of pill-bleed is about the dosing of those drugs. There’s no medical reason to bleed monthly on hormonal birth control. For more information, see my book Period Repair Manual.