Which hormone is primarily responsible for the preparation of the uterus for pregnancy?

The hormone primarily responsible for preparing the uterus for pregnancy is progesterone. This hormone plays a crucial role in the menstrual cycle and early stages of pregnancy. After ovulation, progesterone is secreted by the corpus luteum, which forms in the ovary. Its main functions include thickening the lining of the uterus (the endometrium) to create a suitable environment for a fertilized egg to implant and supporting early pregnancy by maintaining the endometrial lining. If implantation occurs, progesterone levels remain elevated to sustain the pregnancy until the placenta takes over hormone production.

In contrast, estrogen, while important for the development of the uterine lining and regulation of the menstrual cycle, does not solely prepare the uterus for pregnancy. Testosterone is primarily associated with male reproductive functions and has no direct role in preparing the uterus. Luteinizing hormone, although important for triggering ovulation and stimulating the production of estrogen and progesterone, does not directly prepare the uterine lining for pregnancy. Hence, progesterone is the key hormone in this context.