Serious adverse events 'very rare' in first trimester induced abortions

Procedural-induced abortion may be slightly safer than pharmaceutical-induced abortion, although both are safe and effective, according to researchers.

Prior studies that compared procedural-induced abortion (IA) with pharmaceutical IA in the first trimester “were prone to selection bias, were underpowered to assess serious adverse events (SAEs), and did not account for confounding by indication,” Ning Liu, PhD, a research methodologist with ICES in Ontario, Canada, and assistant professor at the University of Toronto, and colleagues wrote in Annals of Internal Medicine. So, the researchers conducted a population-based cohort study to compare the risk for adverse events after an IA using mifepristone-misoprostol vs. a procedural IA.

The researchers studied two comparisons. First, they looked at data from 39,856 women who were dispensed mifepristone-misoprostol and 65,176 women who underwent a procedural IA in nonhospital outpatient clinics at 14 weeks’ gestation or earlier. Secondly, they compared outcomes of the 39,856 women who received mifepristone-misoprostol with 8,861 women who underwent an ambulatory hospital-based procedural IA at about 9 weeks' gestation or less.

Of the participants, the mean age at IA was 29 years, 25% resided in low-income neighborhoods and 6% were in rural areas.

The researchers primarily looked for any SAEs within 42 days, including severe maternal morbidity, end-organ damage, ICU admission or mortality.

In the first comparison group, 133 women experienced an SAE after mifepristone-misoprostol IA — 3.3 per 1,000 — vs. 114 after a procedural IA — 1.8 per 1,000 (RR = 1.87; 95% CI, 1.44-2.43). Additionally, the respective rates of any adverse event were 28.9 per 1,000 vs. 12.4 per 1,000 (RR = 2.33; CI, 2.11-2.57), according to the researchers.

In the second comparison group, 133 women in the medication group experienced an SAE vs. 27 in the procedural group (3.3 per 1,000), yielding a relative risk of 1.04 (95% CI, 0.61-1.78). The respective rates of any adverse event in this group were 31.2 per 1,000 vs. 24.9 per 1,000 (RR = 1.25; CI, 1.04-1.51).

“The current findings underscore the apparent overall short-term safety of accessible first-trimester IA, especially for SAEs, which are very rare,” Liu and colleagues wrote.

The researchers also noted that “adverse events were more commonly seen among women who had a procedural IA in an ambulatory hospital setting than in an outpatient clinic.”

“Beyond different allowances for maximal gestational age at IA, one reason for such differences may be that such complications are more accurately recorded for procedural IA done in an ambulatory hospital setting than those done in a woman's health clinic,” they wrote.

Liu and colleagues concluded that “although rare, short-term adverse events are more likely after mifepristone-misoprostol IA than after procedural IA, especially for less serious adverse outcomes.”

“Within a universal health care system, there was a slightly higher risk for SAEs up to 42 days after an IA with mifepristone-misoprostol compared with outpatient procedural IA in the first 14 weeks of pregnancy,” the researchers wrote. “On comparing mifepristone-misoprostol with ambulatory procedural IA done in hospital up to an estimated 9 weeks' gestation, the risk for SAEs did not differ, but mifepristone-misoprostol was associated with a higher risk for any adverse outcome, ED use, and subsequent procedural IA.”

In an accompanying editorial, Carol J. Hogue, PhD, MPH, Professor Emerita of Epidemiology and Jules and Uldeen Terry Professor Emerita of Maternal and Child Health at Emory University’s Rollins School of Public Health, wrote that the study “provides clear evidence that self-managed abortion is safe and effective.”

“Thanks to Ontario's laws and policies about free access to all types of abortion in the first trimester, coupled with an electronic medical records system that allows for longitudinal assessment, the authors have produced a rigorous population-based study,” she wrote.

Hogue also wrote that, “within the United States, a raging war on reproductive health care is not healthy for women or their children.”

“Part of the increasing maternal mortality in the United States, as compared with other high-resource countries, has been attributed to increasing inaccessibility of safe abortions, especially since 2009, as restrictive abortion policies became more stringent and more pervasive,” she wrote.

References:

• Hogue CJ, et al. Ann Intern Med. 2023;doi:10.7326/M22-3634.
• Liu N, et al. Ann Intern Med. 2023;doi:10.7326/M22-2568.