Randomized Trial of Very Early Medication Abortion.

BACKGROUND

Medication abortion, with a combination of mifepristone and misoprostol, is highly effective and safe. However, there is insufficient evidence on efficacy and safety at very early gestations before a pregnancy can be visualized with ultrasonography.

METHODS

We conducted a multicenter, noninferiority, randomized, controlled trial involving women requesting medication abortion at up to 42 days of gestation with an unconfirmed intrauterine pregnancy on ultrasound examination (visualized as an empty cavity or a sac-like structure without a yolk sac or embryonic pole). Participants were randomly assigned to either immediate start of abortion (early-start group) or standard-care treatment delayed until intrauterine pregnancy was confirmed (standard group). The primary outcome was complete abortion. The noninferiority margin was set at 3.0 percentage points for the absolute between-group difference.

RESULTS

In total, 1504 women were included at 26 sites in nine countries and were randomly assigned to the early-start group (754 participants) or the standard group (750 participants). In an intention-to-treat analysis, a complete abortion occurred in 676 of 710 participants (95.2%) in the early-start group and in 656 of 688 (95.3%) in the standard group; the absolute between-group difference was -0.1 percentage points (95% confidence interval, -2.4 to 2.1). Ectopic pregnancies occurred in 10 of 741 participants (1.3%) in the early-start group and in 6 of 724 (0.8%) in the standard group, with one rupture before diagnosis (early-start group). Serious adverse events occurred in 12 of 737 participants (1.6%) in the early-start group and in 5 of 718 (0.7%) in the standard group (P = 0.10); the majority were uncomplicated hospitalizations for treatment of ectopic pregnancy or incomplete abortion.

CONCLUSIONS

Medication abortion before confirmed intrauterine pregnancy was noninferior to standard, delayed treatment with respect to complete abortion. (Funded by the Swedish Research Council and others; VEMA EudraCT number, 2018-003675-35; ClinicalTrials.gov number, NCT03989869.).