Accuracy of assessment of pregnancy duration by women seeking early abortions

Background Advances in medical abortion might allow women seeking early abortions to terminate their pregnancies safely and effectively without medical supervision. We investigated whether such women can calculate pregnancy duration accurately, a key step in unsupervised use. Methods 422 women seeking first-trimester abortions in two clinics (Pune, India, and Atlanta, USA) used a simple worksheet and calendar to calculate the duration of gestation from the date of last menstrual period (LMP) and/or of unprotected intercourse. Clinicians then used standard clinic practices to estimate pregnancy duration. We compared the two sets of estimates, focusing on women who fell into the "caution zone" (ie, had pregnancy durations >8 weeks according to providers, but less than or equal to 8 weeks by their own estimates). Findings The participants were generally representative of the women seeking abortion at the two clinics. 217 (97.7%) of 222 women in Atlanta and 173 (86.5%) of 200 in Pune could produce an estimate of pregnancy duration. Most (85.4% in Atlanta; 93.6% in Pune) of these estimates were within 2 weeks of those made by providers. For estimates based on LMP, only 10.0% (exact 95% CI 6.2-15.0) of women in Atlanta and 9.8% (5.8-15.3) in Pune fell into the caution zone. For estimates based on a date of intercourse, just 7.7% (4.0-13.1) of women in Atlanta and 3.4% (0-17.8) in Pune fell into the caution zone, although fewer women could use this method. Interpretation The vast majority of women seeking first-trimester abortion in this study could accurately calculate pregnancy duration within a margin of error clinically inconsequential for safe use of unsupervised medical abortion.