If wombat has been prescribed 175 mcg then this is way lower than protocols anywhere! Of course if possible dosage can and should be individualised but only within certain limits and with appropriate monitoring. There are sometimes mistakes made by the medical profession, especially from general partcitioners, as reported on here, and several of us have helped members get these corrected.
As I understand it, The mini pill suppresses ovulation in some women - so then there is no oestrogen surge as follicles do not develop - so the progestogen is sufficient to keep the lining thin from your background level of oestrogen. If ovulation is not suppressed then you will produce your own progesterone which should be sufficient to protect the lining (in addition to the progestogen from the mini pill). This is why it is a lower dose (I believe!). If HRT you need to take the progestogen dosage that is sufficient to protect the lining from the additional dose of oestrogen - as you said. Of course when women ovulate their own progesterone is also added to the mix but this cannot be assumed in peri-menopause which is characterised by skipped or longer cycles, hence the dosage.
The risks are taken into account with age. If you look at the scales on this page - balancing risks and benefits:
https://www.menopausematters.co.uk/balance.php - although this is a crude measure you can see the risk/benefit ratio varies with age. Therefore although there are risks - the benefits are thought to outweigh them for women aged under 60 and equal them between 60 and 70. Every woman needs to be counselled about the risks especially when over 60. In any case as I understand it the absolute risk of BC is still very small, when taking HRT and lifestyle factors (body weight, alcohol consumption etc) are equally if not more important:
https://www.menopausematters.co.uk/risks.phpThanks wombat - I only have some general knowledge about the subject - and it's just a question of reading about it - which takes time and not everyone has this to spare!
Hurdity x