A Guide to IUDs
by Dr Peta Wright
L to R: Mirena IUD, Copper IUD
The Mirena IUD is a small T-shaped device that sits in the uterus as a barrier to prevent pregnancy. It also contains a synthetic progestin called levenorgesterol which thins the lining of the uterus and also thickens the cervical mucous.
The mirena is often used for contraception alone or for heavy and painful periods and endometriosis. It is over 99% effective in preventing pregnancy. It can be useful for women who have troubling menstrual cycles, as the progestin inhibits the growth of the lining of the uterus to make periods very light or non-existent for up to 90% of women. It lasts for five years.
The mirena does not routinely suppress ovulation. In this way it is quite different to the pill which completely switches off the ovaries. The mirena allows the ovaries to continue making Oestradiol, progesterone and testosterone and the brain and ovaries keep talking to each other and making and releasing eggs in the background even though most women won’t get a regular period. This means that fertility returns to normal almost as soon as the mirena is removed.
The mirena can cause some cramping but this usually dissipates within the first few days. The other most common side effect of the Mirena is that it usually causes some light unpredictable bleeding for the first few months after insertion.
Some women can have significant hormonal side effects like with any hormonal contraceptive. Only 1/10th of the progestin dose can be measured in the blood so blood hormone levels are very low, however I definitely see some women who are sensitive to the hormone and may have side effects such as skin and hair changes (acne, hair loss), breast tenderness, bloating or mood changes and less than 5% of women report weight gain.
Studies on the impact of mirena on mood and rates of depression and anxiety are mixed. While on one hand a large 2016 Finnish study showed an association (not causation) between young women using the mirena and the pill with a small increased use of anti-depressants, a recent meta-analysis showed no difference in depression rates in women with or without the Mirena.
There are of course many limitations with these studies and my number one guide is to listen to each woman sitting in front of me and believe what she is feeling in her body.
It is difficult to know who will get troubling side effects and who won’t. And while most women have no issues, it is important that if you do experience side effects you have a doctor who listens and validates your experience and concerns. I am sure to tell women about the possible side effects so if they do experience any symptoms we can address them or try something different. In women with a history of depression or known sensitivity to progestins with no period issues and only requiring contraception, I would usually recommend the non-hormonal copper IUD instead.
The risk of infection is very low for IUDs, less than 1 in a thousand. Your doctor will usually test for any STIs before insertion of the IUD to ensure the risk remains low.
Perforating the uterus or migration of the mirena into the pelvis is also very rare occurring in less than 1/1000 insertions.
Occasionally the Mirena may fall out or become malpositioned and this often results in pain or abnormal bleeding. It is easily remedied by removing and/or inserting a new mirena.
The strings from the mirena sit just below the cervix and you can usually only feel them if you felt for them like inserting or removing a tampon. Most partners are unable to feel the strings during sex but if they do, the strings just may need to be trimmed a little by your doctor.
Insertion usually takes place in the doctor’s office for women who are sexually active. It takes around 5 minutes and can be a little uncomfortable. It is a little like a pap smear at first but the passage of the Mirena into the uterus often causes some period like cramps. I recommend that you take some simple analgesia such as two ibuprofen and two Panadol twenty minutes before hand and arrange for someone to drive you home afterwards. Most women tolerate the procedure well and are fine to attend work/school the following day. If the mirena is for a young woman who is not sexually active or for anyone who is not comfortable with insertion while awake, it can be inserted under a general anaesthetic.
While Mirena is a good option for women with difficult periods, the copper IUD can be a better choice if women have normal periods but only require contraception and don’t want or are sensitive to hormonal methods. The copper IUD is a small intrauterine device that acts as a barrier within the uterus to prevent conception. The copper also works to repel sperm. It lasts for 5 years, is as effective as the mirena and has the advantage of being non-hormonal. It can however, make your periods slightly heavier at first.
While the Mirena usually gets all the attention, the copper IUD is a little known excellent choice for women who want reliable, set and forget, contraception without the risk of any hormonal side effects.
The important thing when considering either type of IUD is to be informed, and work with a practitioner who will work with you if you are experiencing any problems. Both options are as reliable as it gets when it comes to contraception and safe and relatively simple to insert (and remove if it’s not for you).
