Effects of parity and gestational age on second-trimester induction-abortion interval in combination with osmotic dilators and gemeprost.

Background: The true prognostic factors for induced medical abortion are unknown. We sought to investigate the effects of a patient's obstetric parameters on the induction-abortion interval in second-trimester medical abortion.

Study Design: We studied 216 consecutive women. Pregnancy was terminated with cervical preparation using osmotic dilators followed by 1 mg vaginal gemeprost administered every 3 h for a maximum of five doses in the first 24 h. All variables are expressed in categorical form (parity, gestational age, maternal age and body mass index) and analyzed by the Cox proportional hazards model.

Results: Parity ≥ 3 was associated with a shorter duration of the induction-abortion interval (adjusted hazards ratio 1.96; 95% confidence interval 1.13-3.40). A gestational age ≥ 16 weeks was associated with a longer duration of the induction-abortion interval (0.71; 0.52-0.98). No significant association was found in maternal age and body mass index.

Conclusions: In combination with osmotic dilators and gemeprost, gestational age and parity are independent factors that affected the induction to abortion interval of second-trimester medical abortion.