Long-Acting Hormonal Contraception
Oral contraception (“OCPs”) uses hormones similar to natural estrogen and progesterone but of greater potency. Long-acting injectables use similar analogues of progesterone, taken by intramuscular injection (Depot-Provera) or by implanting a tiny pellet in the upper arm (Nexplanon). Depot-Provera, available since 1992, is given quarterly. Nexplanon is good for three years. These cause the pituitary to cease producing the ovarian stimulatory hormone LH, thus shutting down ovulation, inhibiting the cervical mucus and making the lining of the uterus inhospitable to pregnancy. This combination of three effects provides very effective and reliable contraception. The failure rate for Depot-Provera is less than 1% per year and there are no known failures of the Nexplanon device.
Most oral contraception requires the patient to take one pill daily, at about the same time. To receive similar contraception by taking an injection every three months or by having a minor insertion every three years saves substantial trouble.
In the 1990s a device similar to the Nexplanon, the Norplant, was used in the United States. This six-pellet method was also extremely effective but, by having six parts, was much more trouble than the Nexplanon. As a local Norplant instructor, I taught about a hundred Massachusetts physicians how to insert and remove that device. Placing a Nexplanon is much easier and free of complications.
Side effects of both of these methods are irregular bleeding, since the lining of the uterus may respond incompletely to the progestin analogue.