Oral contraceptives are a type of pills that contain 2 types of hormones an estrogen and a progestin in different combinations, that are close to the natural sexual hormones that are produced in the ovaries of every woman. The contraceptive mechanism of the pills is explained by the following therapeutic mechanisms:

• Inhibition of the ovulation
• Increase in viscosity of the mucous in the cervix of the uterus miking it impenetrable to spermatozoons
• Changes the mucous membrane of the uterus, affecting the ability of the impregnated ovule to attach to it
• Decreases the movement ability of spermatozoons in the fallopian tubes

The combination of all those factors make oral contraceptive the most effective method of unwanted pregnancy prevention.

There are 3 types of oral contraceptives:

• Monophasic contraceptives containing in each pill the same dosage of hormones: Yasmin, Alesse, Ovral most commonly used type of contraceptive
• Biphasic contraceptives containing two different doses of estrogen and progestine which are taken during the period of 21 days: Jenest, Mircette
• Triphasic contraceptives containing 3 different doses of hormones for the whole course of 21 days: Tri-regol, Cyclessa, Estrostep. The use of such pills completely imitates the physiological secretion of estrogen and progestine in a womens body.

During the menstrual cycle the levels of hormones in a womans body change in 3 phases so the most physiological type of contraceptive is triphasic contraceptive, however it does not mean that they are the best to use as every woman needs to choose the preparation individually. In most cases the preparations used are low dosed monophasic contraceptives.