Progestogen-only contraception

All other types of hormonal cont raception in current use in the world are progestogen -only and share many similar features in terms of mode of action and side effects. Because they do not contain oestrogen, they are extremely safe & can be used if woman has cardiovascular risk factors. The dose of progestogen within them varies from very low to high

The current methods of progestogen-only contraception are • progestogen-only pill, or 'mini-pill' • subdermal implant Implanon® • injectables • hormone-releasing intrauterine system

Mechanism of action 1-periphyral effects *local effect on cervical mucus making it hostile to ascending sperm. *Local effect on the endometrium making it thin&atrophic thereby preventing implantation *Progestin use also causes decreased tubal and endometrial motility. 2-central effects Higher dose progestogen-only methods can act centrally&inhibit ovulation .

Side effects Menstrual disturbances either irregular vaginal bleeding or amenorrhea. Functional ovarian cyst Increase risk of ectopic pregnancy :this has not been confirmed,although it is probably that POP protect much more effectively against intrauterine than ectopic pregnancy.

Progestogen-only pills The progestogen-only pill (POP) is ideal for women who like the convenience of pill taking but cannot take COc. Although the failure rate of the POP is greater than that ofCOC , it is ideal for women at times of lower fertility. If the POP fails, there is a slightly higher risk of ectopic pregnancy

they contain *the second-generation progestogen norethisterone or norgestrel (or their derivatives) *or the third-generation progestogen desogestrel. The POP is taken every day without a break

Particular indications for the POP include: • breastfeeding • older age • cardiovascular risk factors • diabetes.

Injectable progestogens Two injectable progestogens are marketed. • Depot medroxyprogesterone acetate 150 mg (Depo-Provera or DMPA) which lasts around 12-13 weeks . • Norethisterone enanthate 200 mg (Noristerat) which only lasts for 8 weeks and is not nearly so widely used.

Depo-Provera is a highly effective method of contraception and it is given by deep intramuscular injection Most women who use it develop very light or absent menstruation. Depo-Provera will improve PMS and can be used to treat menstrual problems such as painful or heavy periods. It is particulary useful for women who have difficulty remembering to take a pill

Particular side effects of Depo-Provera • weight gain of around 3 kg in the first year, • delay in return of fertility - it may take around 6 months longer to conceive compared to a woman who stops COC, • persistent menstrual irregularity ,irregular vaginal bleeding may occur or amenorrhea in prolonged use of this injection • very long-term use may slightly increase the risk of osteoporosis (because of low oestrogen levels)

This injection can be given Within five days after the onset of menses, or within 6 weeks after delivery if breast-feeding infant. Also it can be used after having an abortion

Particular indications for depo provera -contraindication to estrogen -Following rubella vaccination in peurperium. -Husband waiting for effect of vasectomy. -Mental retarded women. . -Breast-feeding. -population control in developing countries.

Subdermal implants Implanon consists of a single silastic rod that is inserted subdermally under local anaesthetic into the upper arm. It releases the progestogen etonogestrel 25-70 Mg daily (the dose released decreases with time), which is metabolized to the third-generation progestogen desogestrel. Implanon was introduced into the UK in the late 1990s Other type of implant is the six-rod implant Norplant, which is withdrawn from the market

It lasts for 3 years and thereafter can be easily removed or a further implant inserted. Implanon is particularly useful for women who have difficulty remembering to take a pill and who want highly effective long-term contraception. There is a rapid return of fertility when it is removed.

Emergency contraception Post-coital contraception is any drug or device used prevent pregnancy after unprotected intercourse There are two types of emergency contraception[EC]

A-hormonal emergency contraception 1-Combined oestrogen&progesterone[CEP]: Combination of 100 microgram ethinyl estradiol &0.5 mg levonorgestrel is taken twice the two doses being 12 hours apart&started within 72 hours of unprotected intercourse Nausea&vomiting are common side effects. The precise mechanism of action is not known but probably involves disruption of ovulation or corpus luteal function depending on the time in the cycle when hormonal EC is taken so it inhibit ovulation or interfere with implantation.

2-Levonorgestrel alone: Levonorgestrel 0.75 mg taken twice with two doses separated by 12 hours ,it may be more effective&better tolerated It has to be taken within 72 hours of an episode of unprotected intercourse and is more effective the earlier it is taken

B -intrauterine device A copper-bearing IUD is highly effective post-coital contraceptive with failure rate less than 1%,used up to five days after the estimated day of ovulation.It prevent implantation &the copper exerts an embryotoxic effect The hormone-releasing IUS has not been shown to be effective for EC and should not be used in this situation