Enrolled women will be randomized based on their ovulation pattern. Ovulatory women will be randomized to either natural cycle or estradiol + progesterone substituted cycle treatment for FET. Anovulatory women will be randomized to either estradiol + progesterone substituted cycle or gonadotropin stimulated cycle treatment for FET.~Included women will undergo blood testing every two weeks for serum estradiol and progesterone levels until gestational age 9+6. Routine vaginal ultrasounds will be perfomed as well as additional pregnancy ultrasounds.~Secondary obstetric outcomes will be investigated using the womens medical journals.~All the treatments are considered standard treatments for FET.
The aim of the present study is to investigate serum estradiol and progesterone levels in women conceiving after natural, estradiol + progesterone or gonadotropin stimulated frozen embryo tranfer (FET) cykles.