Long acting methods of contraception.
Long acting methods of contraception have been developed and refined over the last 10 years. From the classical long acting progestogen-only depot preparations we now have a range of delivery systems including both combined and progestogen only injection systems and vaginal rings also containing either progestogen only or oestrogen and progestogen in combination. Subcutaneous implants at present containing only a progestogen, offer a range of durations from 2-5 years. The efficacy of these methods is high, with failure rates as low as 0.1 per 100 woman years. However, with progestogen only systems a significant proportion of women develop unpredictable menstrual bleeding, which with counselling is acceptable. The commonest reason for discontinuation still remains menstrual disorders and recent WHO workshops have investigated the cause of this bleeding and refined the reference periods of analysis. The method of action of progestogen-only systems is primarily cervical mucus blockade and prevention of sperm penetration. However, they also tend to produce a thinned atrophic endometrium. Ovarian effects ranging from complete anovulation to disordered luteal phase, persistent follicles and disorganised hormone production add to the contraceptive effect in more than half of the treatment cycles, but cause some of the menstrual disturbance. All these long acting methods are essential to family planning programmes, offering highly acceptable, and in some cases novel methods with high efficacy.
Newton
J
J
Academic Department of Obstetrics and Gynaecology, Birmingham Maternity Hospital, UK.
D000282:Administration, Intravaginal; D003267:Contraception / Q000379:methods*; D003271:Contraceptive Agents, Female / Q000494:pharmacology; D003274:Contraceptive Devices, Female; D005260:Female; D006801:Humans; D007436:Intrauterine Devices, Medicated; D010053:Ovary / Q000187:drug effects; D019736:Prostheses and Implants; D013997:Time Factors
D003271:Contraceptive Agents, Female