Hi Tc
INteresting of you to raise this...
Sorry I'm too tired to write about it now in detail but didn't want you to think you were being ignored...
In a nutshell it's all about oestrogen receptors -we have two (maybe more?) and estriol is weaker in respect of one of them (either alpha or beta) whereas it has greater affinity for the other one ( either alpha or beta - I can never remember which way round.
It is some years since I read about all of this so the refs aren't to hand but the doses are worked out for both etriol and estradiol products to be equivalent and to do approx the same job (maturation of vaginal tissues and alteration of ph etc) - trials have shown this and the research has been published. Will look them up if you would like me to find them?
If the dose you are on is not working for you then it maybe needs increasing or changing to the other product - as we all react slightly differently the dose and preparation may need tweaking.
In fact there
is only one are two estradiol products - Vagifem,
and the Estring , and two estriol products - generic 0.01% cream and Gynest 0.1% cream and they all have different fillers too.
They are all listed here: https://www.menopausematters.co.uk/local.phpThe pregnancy issue is a red herring in the sense that we have the receptors and the hormones acts on them to do the job and it's a natural hormone. In fact some "alternative" sites wax lyrical about estriol as the answer to HRT, mainly because of the receptor affinity difference.
Checkout Maryjane's posts about VA and Dancinggirl's "Burning Club" thread in Private Lives for lots of tips and info on VA.
Hope this doesn't sound too vague as I'm v tired! Will look up more if you would like me to!
Hurdity x
Edited to correct a mistake!