Very Early Abortion Non-Inferior to Standard Medication Abortion Timing

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Trial confirms what previous observational studies have found

by
Rachael Robertson, Enterprise & Investigative Writer, MedPage Today

November 6, 2024

Initiating medication abortion early was just as effective as standard medication abortion timing, an international randomized controlled trial found.

Intention-to-treat analysis revealed that complete abortion occurred in 95.2% of early-start participants and in 95.3% of those with standard timing, meaning there was only an absolute between-group difference of -0.1 percentage points (95% CI -2.4 to 2.1), reported Karin Brandell, MD, of the Karolinska Institute in Stockholm, and colleagues in the New England Journal of Medicine.

Serious adverse events were reported in 1.6% of the early-start group and 0.7% in the standard group (P=0.10); the majority of these events were uncomplicated hospitalizations for treatment of ectopic pregnancy or incomplete abortion. Ectopic pregnancies occurred in 1.3% and 0.8%, respectively, with one rupture before diagnosis in the early-start group.

While medication abortion with mifepristone and misoprostol is well established as safe and effective, there is insufficient evidence about its use in early gestations before pregnancy can be visualized via ultrasound. Clinicians often delay abortion treatment until the pregnancy can be visualized out of concerns that the pregnancy could be ectopic. The American College of Obstetricians and Gynecologists has refrained from giving specific recommendations for medication abortion before intrauterine pregnancy has been confirmed.

“In this trial, as well as in previous observational studies, early diagnosis of an ectopic pregnancy was possible regardless of whether abortion treatment was started early or delayed,” the authors wrote. They also noted that evaluating very early abortion is more important than ever because of the prevalence of abortion bans after 6 weeks’ gestation.

The authors concluded that this trial’s results “indicate the non-inferiority of the early start of medication abortion before confirmed intrauterine pregnancy, as compared with the standard approach of delaying abortion until an intrauterine pregnancy is confirmed.”

Sheila Mody, MD, MPH, of UC San Diego Health, who wasn’t involved in the study, told MedPage Today that having a randomized controlled trial is a major step since “prior studies that evaluated early start medication abortion were retrospective.”

“Clinicians may not initiate early-start medication abortion without such a prospective study showing that early start is non-inferior to the delayed-start medication abortion,” she said. Having this evidence is significant because “only offering delayed-start medication abortion creates a barrier to medication abortion” and “most patients want to initiate medication abortion when they first seek abortion care,” Mody said.

This multicenter, non-inferiority, randomized controlled trial of 1,504 women took place from March 2019 through April 2023 at 26 sites in nine countries: Austria, Australia, Denmark, Finland, Nepal, New Zealand, Norway, Scotland, and Sweden. Participants were women 18 and older who spoke English or a local language and were requesting medication abortion up to 42 days gestation with an unconfirmed intrauterine pregnancy on a vaginal ultrasound. Signs or symptoms of a pathologic pregnancy, risk factors for ectopic pregnancy, and contraindications to medication abortion were exclusion criteria.

Women were randomly assigned to either the early-start group (n=754), which entailed starting the medication abortion the day or the day after they were included in the trial, or to standard-care treatment (n=750), with delay until intrauterine pregnancy was confirmed. Serum or plasma chorionic gonadotropin (hCG) was assessed at all pre-abortion visits (except in Nepal, where it was assessed only before intrauterine pregnancy was confirmed). Those whose baseline hCG human level exceeded 5,000 IU per liter were evaluated by a gynecologist for potential ectopic pregnancy.

All participants received 200 mg mifepristone orally, followed by 800 μg misoprostol administered vaginally, sublingually, or buccally 24 to 48 hours later. If bleeding had not started within 3 hours, an additional 400 μg dose misoprostol was administered (except in Australia).

The primary outcome was complete abortion, defined as no ongoing intrauterine pregnancy or need for surgical abortion within 30 days of treatment. Secondary outcomes included incomplete abortion, additional medical treatment, infections treated with antibiotics, unscheduled telephone contacts, unscheduled visits, and acceptability measures including days with bleeding and maximum pain.

Adverse events were defined as complications related to abortion treatment or the trial and serious adverse events were defined as all conditions resulting in hospitalization for at least 24 hours or hemorrhage resulting in blood transfusion.

The non-inferiority margin was 3.0 percentage points for the absolute between-group difference. Baseline characteristics were similar between groups, including average age (30) and body mass index (25); 34% of women were nulliparous and 44% had an abortion previously.

Authors noted that the trial was not designed to evaluate women with pregnancy of unknown location and those with probable intrauterine pregnancy separately. Additionally, women with pathologic pregnancy were not followed for secondary outcomes and there were imbalanced levels between groups. They didn’t collect detailed race and ethnicity information, which limits the generalizability of the results.

Mody also pointed out that the typical repeat dose of misoprostol is 800 μg, not 400 μg and that in the U.S., the second hCG is done 24 to 48 hours after misoprostol to see a 50% decline that indicates completed medication abortion. She said that this earlier hCG follow-up helps clinicians find out sooner if the pregnancy was intrauterine rather than ectopic.