Write the chemical name of one antifertility drug.

Hint:Antifertility drugs are chemical compounds which inhibit the action of hormones that lead to pregnancy. They effectively prevent the fertilization of the eggs produced by the female by blocking the sperms.

Complete step by step answer:
Antifertility drugs are essentially synthetic hormones which are made up of a mixture of estrogen and progesterone derivatives which are more effective than the natural hormones. Now, let us understand how this drug works.
When antifertility pills are taken, the mucus present in the cervix gets thickened. This makes it very difficult for sperm to enter the uterus and fertilize the egg and hence chances of pregnancy gets reduced. The main reason behind this is progesterone present in the pills. It is a hormone which suppresses ovulation in women.

Norethindrone, having chemical formula \[{{C}_{20}}{{H}_{26}}{{O}_{2}}\] is a well-known antifertility drug. It is also sometimes called as Norethisterone and sold under many brand names in the market. It is a progestin medication used in birth control pills, menopausal hormone therapy, and also plays an important role in the treatment of gynecological disorders. There are certain side effects of norethisterone which include menstrual irregularities, headaches, breast tenderness, mood changes, acne, etc.
Advantages of these pills:
The chance of cancer in the uterus gets reduced if the pills are taken in long-term dose.
These pills also provide protection against pelvic inflammatory diseases.
Progesterone also acts as an anti-inflammatory drug. It regulates the immune system.

Note: There are certain things that a person should keep in mind while consuming these antifertility drugs, such as:
Always consult your physician before taking any type of medication.
The cycle of medicine should be maintained properly.