Effect of Mirena on menstrual bleeding

A woman’s bleeding pattern can influence whether or not she decides to continue with a particular contraceptive. For example, a telephone survey of 1300 women in the Netherlands revealed that 80% of them would prefer a change to lighter, shorter or less painful menstruation¹. Mirena offers this benefit as the menstrual blood loss decreases and the number of bleeding days declines^2,3 although initially there may be an increase in total bleeding days (menstrual and inter-menstrual spotting days combined). Excessive bleeding and spotting may lead to premature Mirena removal while those with infrequent bleeding or amenorrhea have a higher continuation and satisfaction rate with Mirena⁴.

Counselling about changes in menstrual bleeding can ensure unnecessary removals and hence high continuation rates and user satisfaction. Information received at the placement visit, particularly on the possibility of occasional missing periods, has been shown to improve the level of user satisfaction⁵.

Women should be informed that Mirena will produce changes in menstruation patterns during its use, including:

• irregular spotting and scanty (i.e. light) bleeding, with a gradually decreasing total bleeding volume during the first 3–6 months
• some 20% of women will experience no monthly bleeding at all within the first year of use

Counselling can be aided by the use of simple and easy-to-understand menstrual diary (see Figure15 and also the Resources section to download a copy of the chart) to keep track of the changes in bleeding pattern when using Mirena.

Figure 15: Mirena menstrual diary.

Effective counselling helps women to understand and accept the change in their bleeding pattern as a positive health benefit. The advantages of diminished monthly bleeding, duration of bleeding and dysmenorrhea are supported by the positive and objective benefits of increased hemoglobin and ferritin levels⁶.

A survey of Mirena users in clinical practice showed that infrequent bleeding or absence of menstruation was strongly associated with Mirena continuation⁴ i.e. it is seen as a benefit.

Patients using Mirena should be reassured that the absence of bleeding is most unlikely to signify pregnancy (in case of doubt, a pregnancy test should be performed). Similarly, women should be advised that the absence of bleeding does not indicate a hormonal abnormality and that normal menstrual bleeding will return within the first month after removal of Mirena³.

It can prove helpful to advise women on the difference between bleeding and spotting, thus avoiding any confusion between them, as some women may perceive spotting as bleeding.

While some patients take Mirena to control heavy menstrual bleeding, for others, it is an added value to their contraceptive method.