Birth control pills (oral contraceptives) check ovulation by inhibiting the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) that are necessary for ovulation.
Hence, no eggs are released in a woman on the pill and conception cannot occur.
Most commonly used birth control pills are combine pills.
It contains synthetic progesterone and estrogen in doses high enough to check ovulation.
Oral pills like Mala D, Mala N, etc., are taken daily while the oral pill Saheli is a weekly tablet.
Emergency contraceptive pills are used for treatment of sexual assault (like rape), unprotected sexual contact, missed pills and some other reasons due to which there is risk of pregnancy.
These emergency contraceptive pills do not prevent fertilization, but they make uterus unfavourable for implantation and also they make cervix hostile for sperms.
Oral pills are very effective with lesser side effects. Oral contraceptives act by-
Inhibiting ovulation.
Inhibiting motility and secretory activity of oviducts.
Changing the consistency of cervical mucus impairing its ability to allow passage and transport of sperms.
Altering the uterine lining to make it unsuitable for implantation.