Hi Nut cluster.
I’m clearly not female (I missed the social cues upon joining the forum regarding using a cat as my profile picture), I don’t have much to add regarding estrogen but I have always been intrigued with vitamin D biology during pregnancy and your post captured my interest so please excuse me if this is a little off topic but wanted to share.
Cholecalciferol / vitamin D3 is converted via hydroxylation into the blood storage form calcifediol which is then further converted into its hormonal form, calcitriol, mostly (but not exclusively) by the kidneys. The blood level of calcitriol is maintained in a strict range to maintain calcium homeostasis and is regulated by parathyroid hormone. During pregnancy the levels of calcitriol, the hormonal form, increases by double or triple to levels you’d see in granulomatous disease or intoxication but without hypercalcemia. The body deliberately raises both calcitriol and binding proteins in order to support placental development, immuno-regulation and fetal skeletal growth. The levels then fall back into normal range 2-6 weeks postpartum. There is still much we don’t understand about this intriguing process.
It’s interesting that many female warriors report skipping cycles during pregnancy and to also consider why they return postpartum (and perhaps also why MS relapse may occur postpartum), and although tempting to speculate it may have something to do with the increase in calcitriol and its immuno-modulatory properties, probably an oversimplification - the body is just so complex.
Dr. Hollis & Dr. Wagner have a combined century or so of research looking at vitamin D and reproductive outcomes, this was a great talk from last year although can’t recall if they cover the specifics of the points above.