One of the widely used birth control method is use of oral contraceptive pills. These include combination pills (have both estrogen and progestin), progestin only pills. COCP's work by preventing ovaries from ovulation. It must be taken every day at the same time. Benefits of COCP's include: easy reversibility if the couple wants to start family, decreases the PMS, relieves dysmenorrhea and menorrhagia, improves acne, lowers risk of ovarian, endometrial and colon cancers, used to treat PCO's and beneficial for bone density. Disadvantages include: no protection against STD's, hypercholesterolemia, DVT, strokes and MI, increased risk of breast and cervical carcinoma, irregular bleeding, bloating, breast tenderness, nausea, depression and weight gain. Its effectiveness is 99% but due to improper use may decrease its effectiveness. Progestin only pills slows progress of egg through fallopian tube and thins the endometrium. Benefits include: reversible method, can be taken safely in migraine, hypertensive and patients with heart conditions, low interference with breast feeding and lower risk of endometrial cancers. Disadvantages of progestin pills include: difficult regime, no safety against STD's, may cause abnormal uterine bleeding, ovarian cyst, decreased libido, weight gain, breast tenderness, hirsutism and ectopic pregnancy.