The Mirena is a contraceptive device so delivers progesterone locally to the uterus thereby preventing pregnancy but also keeps the womb lining thin. In the peri meno stage some women will often still get some bleeding with the Mirena if using oestrogen alongside but when post menopause there is less likely to be any bleeding.
The progesterone in oral HRT or combined HRT patches will not protect the womb lining as efficiently as the Mirena in the peri stage so the sequential HRT regime works better. If you use conti HRt in the peri stage then you are likely to get erratic or heavy bleeding.
This is a bit rambling but hopefully explains things??
Here is the section on this site that explains about the Mirena:
MIRENA
Mirena is a levonorgestrel (type of progestogen) releasing system which sits inside the womb, gradually releasing the progestogen into the womb. It is licensed in the UK and Ireland as a contraceptive agent, for treatment of heavy periods and, from August 2004, also for the progestogen component of HRT. It can be used in both the perimenopause and postmenopause and it is particularly useful for:
Persistent progestogenic side effects from systemic HRT despite changes in type and route of progestogen.
When contraception is required along with HRT in the perimenopause.
When withdrawal bleeds on sequential HRT are heavy, after investigation if indicated. (see WHEN TO BE REFERRED )
With Mirena in place, systemic estrogen alone can be taken as the Mirena provides adequate protection of the womb lining and the estrogen dose and route can be tailored to meet the individual's needs.
Progestogenic absorption throughout the body is minimal so reducing progestogenic side effects. The effect of Mirena on the womb lining can significantly reduce bleeding and when used as part of an HRT regimen, in time, 30 to 60% of women have no bleeding at all. Although Mirena used for contraception is licensed for 5 years, the license for use for the progestogen part of HRT is currently 4 years.
DG x
Price: £88.00
