What is recommended period for taking a post-coital contraceptive pill after unprotected intercourse?

Explanation

• Oral Contraceptive Pills Or Birth Control Pills are pills containing a number of hormones that help to prevent unwanted pregnancy.
• Birth control pills are to be taken within 72 hours of or 3 days of unprotected sex.
• There are mainly three types of oral contraceptive pills:

1.         combined estrogen-progesterone
2. progesterone only
3. continuous or extended use pill

Mechanism of Action

• Progesterone is the hormone that is responsible for pregnancy. Progesterone in the birth control pill mainly inhibits the mechanism of Ovulation, which further inhibits Follicular Development.
• After drug administration, Progesteron Negative feedback mechanism acts on the Hypothalamus and it reduces the action of Gonadotrophin releasing Hormone and also decreases the level of Follicle-stimulating hormone (FSH) and Luteinizing Hormone. 
• These Hormonal changes will prevent follicle development.
• Another primary mechanism of action says that progesterone inhibits the ability of sperm to penetrate through the cervix and upper genital tract by changing the normal flora of the cervical mucus.