Background Advances in medical abortion might allow women seeking early abo
rtions to terminate their pregnancies safely and effectively without medica
l supervision. We investigated whether such women can calculate pregnancy d
uration accurately, a key step in unsupervised use.
Methods 422 women seeking first-trimester abortions in two clinics (Pune, I
ndia, and Atlanta, USA) used a simple worksheet and calendar to calculate t
he duration of gestation from the date of last menstrual period (LMP) and/o
r of unprotected intercourse. Clinicians then used standard clinic practice
s to estimate pregnancy duration. We compared the two sets of estimates, fo
cusing on women who fell into the "caution zone" (ie, had pregnancy duratio
ns >8 weeks according to providers, but less than or equal to 8 weeks by th
eir own estimates).
Findings The participants were generally representative of the women seekin
g 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. Mos
t (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 9
5% CI 6.2-15.0) of women in Atlanta and 9.8% (5.8-15.3) in Pune fell into t
he 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 cautio
n 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 a
bortion.