Mirena IUD – what you need to know

I’m often asked: Is the hormonal IUD, like the Mirena, the better option for hormonal birth control?

Hmmm, it’s a toughie.

As hormonal intrauterine devices (IUDs) allow ovulation at least some of the time, I would reluctantly agree that, yes, they are the better choice of hormonal contraceptive.

BUT… to make a truly informed decision over your birth control it’s important to understand how the hormonal intrauterine devices (IUDs) work, as well as their pros and cons.

Hormonal IUDs go under a number of brand names including Mirena, Liletta, Kyleena and Skyla which can be used for 3-5 years depending on the brand. The reason some women do better with one brand of hormonal IUD than another can be the different amounts of progestin it contains (13.5mg-52mg) and amount of progestin that is released every day (this ranges from 14-20 mcgs).

So how do hormonal IUDs work? 

A hormonal IUD is a T shaped plastic device about 3cm wide/tall that is placed in the uterus. It has 2 thin threads that hang down a little way from your womb into the top of your vagina. The IUDs release progestin into your body, which is a synthetic version of the hormone progesterone. Can I be clear. It is NOT progesterone and does NOT have any of the benefits.

IUD progestin prevents you getting pregnant in 3 ways:

  1. It affects the communication between your brain and ovaries so some people with some brands don’t ovulate (yep, it depends on each individual and on each brand of IUD! More on that below.)
  2. It thins the uterine lining out making implantation of a fertilised egg impossible
  3. Progestin can also thicken cervical fluid, which makes it more difficult for sperm to reach an egg

These are the advantages of the hormonal IUD:

  • They are a highly effective and convenient way to not get pregnant – it’s over 99% effective and you don’t need to remember to take a pill every day.
  • Lightens periods – for people suffering with heavy periods the lighter periods that the hormonal IUD can bring can be a much needed relief. As the uterine lining is thinned you can have lighter periods or if you’re not ovulating your period could disappear completely (but see below why this is NOT a good thing).

So now turning to the disadvantages of the hormonal IUD:

  • Insertion may be extremely painful
  • Cramping and bleeding after insertion
  • Irregular bleeding and spotting common during the first 3-6 months
  • Suppresses ovulation: a study suggested that the Mirena coil suppresses ovulation only in the first year of use, but after that ovulation returns for all but 25% of users (PMID: 19920976/2113816). HOWEVER, what colleagues and I see in the clinic is actually the opposite. Around 70% of women on the Mirena coil are not ovulating (and this is a BIG deal!) Remember: women only make hormones by ovulating so we really really don’t want to be messing with that.
  • Acne
  • Hair loss
  • Hirsutism
  • Depression (PMID: 28593268)
  • Anxiety
  • Headaches
  • Breast pain or tenderness
  • Weight gain
  • 5% chance of developing ovary cysts (PMID: 12971147)
  • Damages the vaginal microbiome and increases the risk of yeast infections and bacterial vaginosis (PMID: 29458551)
  • 5% change of explosion (yes, the IUD can come out!)
  • 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
  • Many women report a long wait to get their IUD removed
  • Cannot protect against sexually transmitted infections
  • Not really a disadvantage but I think we need to consider whether having an object in our body every day releasing a synthetic hormone is actually necessary when we are only fertile for 6 days a month!

Similar to what I recommend when you are taking the pill, I always encourage you to read the patient information leaflet for the brand of contraception you are taking or considering taking to see the side effects that the manufacturer shares. It is always very eye opening. You can find this easily online with a quick search.

There are many non-hormonal contraceptives that you can explore, as well as learning the steps to replenish your body after taking the pill.

If you’re keen to be fully informed about your contraceptive choices and ways to support your health through perimenopause, you will love my 6-week live course Embrace Your Cyclical Power.

“PMS kind of switched me into a Mr Hyde every month and I was very upset about it - I felt I was fighting a losing battle of self-control. Now I have learned to be kinder to myself and I can handle PMS and perimenopause much better”.

Christel Ong, Massage Therapist, Singapore