Which hormone initiates the preparation of the endometrium of the uterus for pregnancy?

Estrogen initiates the preparation of the endometrium of the uterus for pregnancy by promoting its growth and thickening during the menstrual cycle. It is essential for creating a suitable environment for implantation of a fertilized egg. FSH (Follicle Stimulating Hormone) is involved in stimulating follicle development in the ovaries, LH (Luteinizing Hormone) triggers ovulation, and Progesterone is crucial for maintaining the endometrial lining post-ovulation and during early pregnancy.