What hormone do the ovaries produce that is essential for maintaining the uterine lining during pregnancy?

The hormone produced by the ovaries that is crucial for maintaining the uterine lining during pregnancy is progesterone. Once an ovum is fertilized and a pregnancy is established, progesterone plays a vital role in preparing the uterus for implantation and sustaining the endometrium, which is the lining of the uterus. This hormone helps to prevent the muscle contractions that can lead to the rejection of the developing embryo and supports the nutrient supply necessary for fetal development.

Progesterone levels rise significantly after ovulation, and if fertilization occurs, it continues to be produced to support the pregnancy. If pregnancy does not occur, progesterone levels decline, leading to menstruation.

In contrast, oestrogen, while also produced by the ovaries, primarily contributes to the development of secondary sexual characteristics and regulates the menstrual cycle, but it does not maintain the uterine lining in the same way progesterone does. Testosterone is mainly associated with male reproductive functions and not typically produced in significant amounts by the ovaries. Follicle stimulating hormone (FSH) is involved in the maturation of ovarian follicles but is not directly responsible for maintaining the uterine lining during pregnancy.