Explanation:
Progesterone is a hormone produced by the ovaries. It plays a vital role in the menstrual cycle and pregnancy. Progesterone is also present in contraceptive pills. The function of progesterone in contraceptive pills is to prevent ovulation. Let's understand the role of progesterone in birth control in detail.

Prevent ovulation:
The primary function of progesterone in contraceptive pills is to prevent ovulation. Ovulation is the process of releasing an egg from the ovary. If there is no egg, fertilization cannot occur. Progesterone in the contraceptive pill prevents the release of an egg by suppressing the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH are responsible for the growth and maturation of the egg. Without these hormones, the egg does not mature, and ovulation does not occur.

Thickening of cervical mucus:
Progesterone in the contraceptive pill also thickens the cervical mucus. The mucus is a fluid that is present in the cervix, which is the lower part of the uterus. The mucus acts as a barrier to prevent the sperm from reaching the egg. Progesterone thickens the mucus, making it difficult for the sperm to penetrate.

Changes in the uterine lining:
Progesterone in the contraceptive pill also causes changes in the uterine lining. The uterine lining is the inner lining of the uterus, which prepares itself to receive the fertilized egg. Progesterone makes the uterine lining less receptive to the fertilized egg, making it difficult for the egg to implant. This prevents pregnancy.

In conclusion, progesterone in contraceptive pills primarily functions to prevent ovulation. It also thickens cervical mucus and changes the uterine lining to prevent fertilization and implantation.

In the excessive presence of progesterone gonadotropins FSH and LH are not reseased (as it gives negative feedback to hypothalamus). As there is no FSH ovulation will be inhibited.