The hormonal IUD is different from all types of hormonal birth control in that it does not suppress ovulation and therefore can permit natural cycling.
Other benefits of the hormonal IUD are that it dramatically decreases menstrual flow and can relieve symptoms of endometriosis.
Pros of the hormonal IUD:
Unlike all other types of hormonal birth control, Mirena does not completely shut down ovulation and hormone production. Officially it doesn’t suppress ovulation at all, but one study found that it does suppress ovulation in 85 percent of cycles during the first year (when the dose of the levonorgestrel drug is higher), and then in 15 percent of cycles after that. Remember, ovulation is beneficial because it’s the only way to make estradiol and progesterone.
Compared to pills and implants, the hormonal IUD delivers a lower dose of a contraceptive drug. The blood level of levonorgestrel in Mirena-users is about one-tenth of pill-users. Unfortunately, even that low dose can cause mood and other side effects (see below).
It’s more effective than almost any other method of contraception, with a failure rate of just 0.7 percent.
After insertion, you don’t need to do anything or take anything, and it lasts three years (Skyla) or five years (Mirena).
In theory, fertility returns to normal almost as soon as you remove a hormonal IUD. (In practice, it can take a little longer.)
It can relieve some of the symptoms of endometriosis. For other endometriosis treatment ideas, read Endometriosis? Treat the immune system.
Cons of the hormonal IUD:
The hormonal IUD releases the contraceptive drug levonorgestrel, which is not progesterone. Side effects of levonorgestrel include acne, hair loss, hirsutism, depression, anxiety, headaches, breast pain, yeast infections, weight gain, and anxiety. (Interestingly, anxiety is also reported by some women with the copper IUD which suggests the anxiety could be the result of something else such as a vagal nerve response to the IUD or the string.)
It causes ovarian cysts in 5 percent of users.
It damages the vaginal microbiome and increases the risk of yeast infections and bacterial vaginosis.
It suppresses ovulation some of the time. (Not all the time like the pill, implant, injection, or Nuvaring.)
It can cause irregular bleeding and spotting during the first three to six months of use. After that, it may completely suppress bleeding or permit a light period. (And in case you’re wondering—yes, that light period is the result of a real menstrual cycle that includes ovulation and progesterone.)
Insertion might be painful. But just to clarify: It’s an in-office procedure that takes a few minutes—it’s not surgery. You’ll probably be instructed to take a painkiller like ibuprofen to ease the cramping, or your doctor may decide to use a local anesthetic (or more rarely, a general anesthetic ).
It could come out. The chance of expulsion is about 5 percent, but it’s more common in younger women, breastfeeding women, and in women who had it inserted immediately following childbirth.
It might cause pelvic inflammatory disease (PID) but only during the first three weeks after insertion, and only if you have a pre-existing infection with gonorrhea or chlamydia.
It carries a small risk of uterine perforation, which could lead to surgery. Perforation occurs in 0.1 percent of users (1/1000) but is more likely if you are breastfeeding.
If and when you want it out, you need to see your doctor. See the copper IUD post for more information about IUD-removal.
It cannot protect against sexually transmitted infections.
It’s riskier if you’re breastfeeding. There’s a greater chance of IUD expulsion and uterine perforation while breastfeeding. Also, levonorgestrel does enter breast milk and reach the baby.
The bottom line about the hormonal IUD (Mirena)
The hormonal IUD is not as healthy as non-hormonal methods such as condoms, fertility awareness methods, Daysy contraceptive device, and the copper IUD. However, it does have the major advantage of reducing menstrual flow and helping to relieve the pain of endometriosis and adenomyosis. The hormonal IUD can be a better choice than surgery or other types of hormonal birth control.
Also, because Mirena does permit ovulation at least some of the time, it is probably the best option of all the types of hormonal birth control.
Is it okay to suppress periods?
Because the hormonal IUD suppresses bleeding, it inevitably raises the question: “Is it okay to not have a period?”
There’s no need to have a menstrual bleed per se, and certainly no need to have a pill-bleed (which is not a period anyway).
But there is a need to have hormones, and ovulation is the only way to make them. According to endocrinology professor Jerilynn Prior, “regular menstrual cycles with consistently normal ovulation…will prevent osteoporosis, breast cancer and heart disease.”
The hormonal IUD is unique in that it suppresses bleeding but permits ovulation and natural cycling. Therefore, if “menstrual suppression” is your goal, a hormonal IUD is really the only way to go.
With the pill, you bleed but don’t cycle.
With the hormonal IUD, you cycle but might not bleed.