Low oestrogen or progesterone?

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I’m struggling to find out for definite what this is a sign of, but the day before my period begins I get an itchy labia (sorry tmi). It stops as soon as my period begins and I don’t have it any other time. I’m assuming it’s related to a drop in hormones. It’s not thrush or anything nasty, it’s happened to me for the past 3 years.
Last month I had a miscarriage, a couple of days before the bleeding began I had the itch in the same place and it was unbearable. Would this indicate a drop in either oestrogen or progesterone? I have pcos. I didn’t have issues conceiving my other children.
My gp will only test if I have 3 or more miscarriages, but I do not want to lose another pregnancy so if I can understand it now I may be able to prevent it happening again? Any experience or advice please?

I think this will be due to the hormones dropping before AF - low oestrogen can cause dryness. It’s supposed to be low at the point before AF so I wouldn’t think it is anything to worry about. In terms of your miscarriage it will be difficult to tell if the drop in oestrogen/progesterone caused the miscarriage or they dropped because the pregnancy wasn’t developing. Was your GP not able to give any advice?