Ans. is d i.e. Inhibiting ovulation Ref. Fogsi Focus - Jan 06 issue - The Modern Pill, Chapter Estrogen Free Pills, p 41; Current concepts in contraception and women health, p 49 Inhibiting ovulation : FOGSI is federation of Obstetrics and gynaecological societies of India and the highest governing body in Obs and Gynae in India. Friends, I know this is quite difficult to digest as we have been studying, Progesterone only pills act mainly by causing thickening of cervical mucus. But read the question once again : here question specifically mentions; ''newer progestational pills". Read what FOGSI supplement has to say about mode of action of Progesterone only pills (also known as Estrogen Free Pills). Cervical Mucus effect : All Estrogen free pills except the newer desogesterel pill primarily rely on changes in cervical mucus as they do not inhibit ovulation consistently. The cervical mucus effect peaks within 3-4 hours after taking the tablet and lasts for about 22 hours. Hence the next tablet must be taken within 27 hours of the preceeding tablet or else the contraceptive benefit of the cervical mucus effect will decrease and finally subside. Inhibition of ovulation: Unlike COC's (Combined OCP's) that almost always prevent ovulation, traditional POP's (progesterone only pills) inhibit ovulation in 40-50% of cycles. A randomized double blind study, performed over 13 cycles showed that 75 micrograms desogestrel daily was sufficient to inhibit ovulation in 97% of cycles. Hence for newer POP's containing desogestre! the primary mode of action is inhibition of ovulation. Fogsi Focus Jan 06 issue on Modern pill, Chapter Estrogen free pill p 41. Thus, for newer progestational agents main mechanism of action is by inhibition of ovulation. Friends, I would like to discuss Progesterone only pills in detail here as Question can be asked on them anytime. Progesterone only pills : Mechanism of action Traditional POP/ Low dose POP Newer POP containing desogestrel Thickening of cervical Mucus Inhibition of ovulation Failure Rate = 2-6/100 women years Failure Rate 0.2 to 0.4/100 women years Indications of all POP's : Category 1 = Unrestricted use : Can be used without restriction in presence of : Age over 16 years Smoking Obesity. Obstetrical & Gynaelogical conditions Post paum use Past History of - In non breast feeding Uterine fibromyoma Breast feeding over 6 weeks postpaum. Ca endometrium - Past H/0 eclampsia Ca ovary. Past H/0 induced or spontaneous aboion Pregnancy induced Jaundice Chronic diseases - Past history of : CNS Epilepsy CVS - Valvular hea disease Hematology - Iron deficiency anemia Thallesemia Sickle cell anemia GIT - Non active hepatitis Infections - Malaria, TB Risk of STD's Category 2: Require careful consideration (Generally should not be used) or relative contraindications of POP's: Acute liver disease Liver tumour (benign or malignant) Severe decompensated cirrhosis Current DVT or pulmonary embolism Breast feeding less than 6 weeks post paum H/O Breast cancer with no evidence of disease for last 5 years Unexplained abnormal vaginal bleeding Use of Rifampicin or anticonvulsants like phenytoin, carabmazepine, barbiturates. Category 3 : Absolute Contraindiactions of POP's : Breast cancer within the past 5 years. Unexplained vaginal bleeding Pregnancy How to use In regular cycles Amenorrhea Recent WHO recomme- * Sta ndation suggest POP any time after being sure should be staed that there is no pregnancy from 5th day of (Additional protection or m. cycle without abstinence from sex need of additional being advised for the contraception. first 48 hours During lactation If female is breast feeding : Sta anytime between 6wks to 6months without any additional; protection. If female is not breast feeding : can be staed before 6 weeks Progesterone only pill should be taken every day without break and at the same time (For traditional POP's).deg For newer desogestrel containing pill, a delay of -12 hours can be accepted. Dealing with missed pills : Progesterone only pill also called as Minipill, is best suited for lactating mothers and is therefore known as Lactational pill.deg If POP (Traditional) have been missed by more than 3 hours or Desogestrel containing by more than 12 hours, then one pill should be taken as soon as possible followed by the usual daily dose.deg Abstinence or use of additional contraception (barrier method) is advised for the next 48 hours.deg Side effects Menstrual disturbances : Most common reason for discontinuation of POP's is irregular bleeding pattern. Other side effects : Headache, Acne, Breast pain, Nausea, Vaginitis and Dysmenorrhea. Carbohydrate metabolism : At high doses, most progestogens adversely affect carbohydrate metabolism whether given alone or in conjunction with estrogen. Hence POP's should not be advised to women with H/O Gestational diabetes mellitus. Also know : Traditional POP's are also known as Low dose progestogen only pills. Main progesterone used are :- Norethisterone 35Oug - Norgestrel 75mg - Levonorgesterel 30Ags. Their main mechanism of action (as discussed earlier) is Thickening of cervical mucus.deg They also : - Render endometrium unsuitable for implantation - Accelerate tuba! motility - Disturb corpus luteal function. A word of caution to all of you out there : Be careful in reading the question - whether question is on Low dose progestins (Traditional pills) or on Newer progestins containing desogestrel.