MEDICATION: Intrauterine System (IUS) 

A progestin-releasing intrauterine device (IUD) is a small, T-shaped contraceptive device that's inserted into the uterus. It's also known as a hormonal IUD or intrauterine system (IUS). 


In New Zealand we have 2 funded intrauterine system options - the Mirena and the Jaydess.  They both release the same type of progestin (levonorgestrel - a synthetic progesterone) but the Mirena contains more progestin than the Jaydess and is also bigger in size.    


Here's a quick rundown:


What it is:

  • A flexible plastic device that releases a small amount of progestin hormone (usually levonorgestrel) directly into the uterus
  • Brands include Mirena, Kyleena, Liletta, and Skyla (each with slightly different hormone doses and durations)

How it works:

  • Thickens cervical mucus to prevent sperm from reaching the egg
  • Thins the uterine lining, making it less hospitable for implantation
  • May suppress ovulation in some cases
  • Protects the lining of the uterus from thickening in conditions of polycystic ovarian syndrome, and other cases of irregular periods with high estrogen.

Key benefits:

  • Highly effective contraception (>99% with perfect use)
  • Can significantly reduce menstrual bleeding and pain
  • Can be used as endometrial protection as part of hormone replacement therapy.  
  • Lasts 3-8 years, depending on the brand and the reason it is being used for (and the age in which it is inserted)
  • Quickly reversible when removed (ie no prolonged impact on contraception)
  • Can be used (under close supervision) to treat endometrial precancer cells and also some endometrial cancer which can enable women to retain their fertility (I think this is really exciting!)

Things to note:

  • Requires insertion by a healthcare provider
  • May cause irregular bleeding, especially in the first few months
  • Some women experience hormonal side effects, though these are usually mild
  • Rates of depression/low mood I (Dr Sam) believe are under recognised, but for most women this improves over 3-6 months and therefore the Mirena is often still beneficial.  The Mirena has higher rates of anovulation and lower mood due to higher doses of progestin that it contains

The hormonal IUD is a popular choice for many due to its effectiveness, convenience, and potential to improve menstrual symptoms. However, as with any method, it's important to discuss the pros and cons with your healthcare provider to determine if it's the right option for you.


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