Asking more questions leads to higher accuracy in self-assessment of pregnancy duration

March 22, 2022

Health care providers must find out how long someone has been pregnant to see if they’re eligible for a medication abortion. To do this, providers often ask a pregnant person the start date of their last menstrual period. Prior research shows that people seeking early abortion care can accurately tell how far along they are using the date of their last period. Sometimes pregnant people are uncertain about the date of their last period, leading providers perform an ultrasound for nearly 1 in 5 people. When people are receiving care in a clinic, needing an ultrasound or a pelvic exam may not be a barrier, but these tests could be a barrier for people receiving remote care.

ANSIRH set out to find out if more or different questions about the timing of the pregnancy could reduce uncertainty and therefore reduce the need for in-person testing. Researchers developed a set of questions that increase the accuracy of self-reported pregnancy duration.

They found that using responses to multiple pregnancy dating questions worked better than relying on one question to correctly identify people who are more than 70 days pregnant. A combination of their responses to the date of their last period, the date they think they got pregnant, and their estimated number of weeks pregnant was more accurate than just asking about their last period.

This study shows that expanding the number and types of questions asked during eligibility screening allows for more comprehensive, accurate, and sensitive assessment of how far along they are among people seeking abortion. Although in-person ultrasound is typically used to establish gestational duration and eligibility for medication abortion, there is growing interest in expanding the use of telemedicine screening and removing ultrasound requirements. This data supports those efforts.

Based on this study's findings, ANSIRH developed an interactive tool that demonstrates how different combinations of questions work in identifying people above or below 70 days gestation, available here.