VP01.06: In the early first trimester, serum estradiol associates with Lactobacillus dominance in the vaginal niche. Issue Volume 58:Issue S1(2021)Supplement (14th October 2021) - Fourie, H.; Al‐Memar, M.; Ng, S.; Lee, Y.; Kundu, S.; Timmerman, D.; Bourne, T.; MacIntyre, D.; Bennett, P.