<prompt> Emergency contraception contains-CyproteroneDesogestrelLNGMedroxyprogesterone  <response>: Ans. is c i.e., LNG Two methods of emergency contraception are available now:1 Hormonal and2 Mechanical IUD There are two types of hormonal emergency contraception emergency window 72 hours1 LNG-only pills most commonly used One tablet of 0.75 mg LNG pill should be taken as soon as possible after unprotected intercourse, followed by a same dose taken 12 h later; both doses must be taken within 72 h of intercourse. Single 1.5 mg dose of LNG is as effective for emergency contraception as two 0.75 mg doses of LNG taken 12 h apart. Failure rate pregnancy rate 0-12 Combined Estrogen and Progestogen Pills Also Known as the Yuzpe Regimen High-dose pills contain 50 pg of EE and 250 pg LNG or 500 pg norgestrel. Two pills should be taken as soon as possible, but not later than 72 h of unprotected coitus; this must be followed by two other pills 12 h later. When only low-dose pills containing 30 pg of EE and 150 pg of LNG 300 pg of norgestrel are available, four pills should be taken as the first dose within 72 h of unprotected intercourse, followed by four more pills after 12 h. Main side effect is nausea and vomiting Failure rate 0-2 The mechanism of action of emergency contraceptive pills has not been clearly established. They may act through 1 inhibition or delay of ovulation, 2 prevention of implantation in the altered endometrium interception main action, and 3 prevention of fertilization due to quick transport of sperms or ova. They cannot interrupt already established pregnancy. 