Medical abortion in the first trimester

Pregnancy can be terminated safely by inducing abortion medically at any stage of gestation. Antagonists such as mifepristone block the action of progesterone and hence result in uterine contractions and increase the sensitivity of the uterus to prostaglandins. In the last 15 years the combination of a single dose of mifepristone (600 mg) followed 48 hours later with a suitable prostaglandin (1 mg gemeprost vaginal pessary or 400 mug oral misoprostol) has been licensed in most countries in Europe and the USA for induction of abortion in the early weeks of pregnancy. The safety and efficacy of these methods is comparable to vacuum aspiration at the same gestation. The complete abortion rate is related to the type and dose of prostaglandin, the route of administration as well as the gestation and parity. Published data suggest that the dose of mifepristone can be reduced from 600 mg to 200 mg without loss of efficacy. Although misoprostol tablets are formulated for oral use, extensive clinical experience has demonstrated vaginal administration is more effective and is associated with fewer side-effects. Successful abortion using medical methods requires a well organized service which includes referral without delay and a robust system of follow up to identify failures. The failure rate as reflected by the number of women who require surgical intervention falls with increasing experience. In those countries where medical abortion has been freely available for about 10 years, such as France, Scotland and Sweden, about 60-70% of eligible women elect for this method.