Summary Safety Review - Birth control hormone systems (intrauterine) - Assessing the potential risk of less breast milk production
September 21, 2017
Birth control hormone (levonorgestrel, LNG)-releasing systems that are placed into the uterus (intrauterine systems, IUS) - Mirena, Jaydess and Kyleena
Potential Safety Issue
Decreased breast milk production (suppressed lactation)
- LNG-IUS products (Mirena, Jaydess and Kyleena) are prescription drug-releasing devices authorized for sale in Canada for birth control. Mirena is also authorized for the treatment of heavy periods (menstrual bleeding) without a known cause.
- Health Canada reviewed the risk of decreased breast milk production with the use of LNG-IUS products because of Canadian reports regarding women using Mirena.
- Health Canada's review concluded that there is currently limited evidence to suggest a link between LNG-IUS products and the risk of decreased breast milk production. Health Canada is considering updating the LNG-IUS product information to mention that cases of decreased breast milk production in women using LNG-IUS have been reported.
Health Canada reviewed the risk of decreased breast milk production with the use of LNG-IUS products because of Canadian reports in women using Mirena. The current Canadian product information for LNG-IUS mentions that these methods of birth control do not seem to affect the amount and quality of breast milk.
Use in Canada
- LNG-IUS products (Mirena, Jaydess and Kyleena) release the birth control hormone levonorgestrel. These products are placed into a woman's uterus to provide birth control for up to 3 to 5 years depending on the product.
- Mirena, Jaydess and Kyleena have been marketed in Canada since 2001, 2013 and 2017, respectively.
- In 2016, most of the prescriptions filled for LNG-IUS products were for Mirena.
Safety Review Findings
- 24 published studies about women who were breastfeeding and using LNG-IUS products were reviewed. The studies concluded that the use of LNG-IUS provides highly effective birth control and that these products do not affect breastfeeding.
- At the time of the review, Health Canada had received 19 Canadian reportsFootnote a of decreased breast milk production in breastfeeding women using LNG-IUS. All the reports were for Mirena. For 13 reports, it was considered that the use of LNG-IUS may have played a role in breastfeeding difficulties. For 3 of these reports, it was considered that the LNG-IUS was probably associated with breastfeeding difficulties, as breast milk production returned to normal when the LNG-IUS was removed. The remaining 3 reports did not have enough information to conclude that the LNG-IUS affected breast milk production.
Conclusions and Actions
- Health Canada's review concluded that there is currently limited evidence to suggest a link between LNG-IUS products and the risk of decreased breast milk production.
- Health Canada is considering updating the product information for these products to mention that cases of decreased breast milk production in women using LNG-IUS have been reported.
- Health Canada will continue to monitor safety information involving LNG-IUS products as it does for all health products on the Canadian market, to identify and assess potential harms. Health Canada will take appropriate and timely action if and when any new health risks are identified.
The analysis that was carried out for this safety review took into consideration information from scientific and medical literature, Canadian and international adverse reaction reports, as well as what is known about the use of these health products in Canada and internationally.
For additional information, contact the Marketed Health Products Directorate.
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