Antiprogesterone compound RU-486 is effective for inducing aboion if the duration of pregnancy is:

Mifepristone (RU 486) an Antiprogestin, degenerates the pregnancy in doses ranging from 200-600mg. This is followed by Misoprostol (prostagladin) in 400ug orally or 800ug vaginally which causes uterine contractions to expel the dead fetus. This regime is -99% successful - If done within 1st 7 weeks -95% successful - If done within 1st 9 weeks