At-home pregnancy testing is quick, easy and highly accurate — if performed on the date of the woman’s expected menstrual period.
Yet in a study of 6,569 women conducted by researchers from Vanderbilt Health and Boston University School of Public Health, more than 40% of the women reported that they tested their urine for human chorionic gonadotropin, a hormone released by the placenta, four or more days before their expected periods.
These very early testers were over five times more likely than were those who tested on the day of their expected menstrual period to get an initial, false negative result, followed by a positive one, if they were pregnant, the researchers reported Jan. 8 in the journal Obstetrics & Gynecology.
They were also over three times more likely to receive an initial, positive test result, followed by a negative one. This likely indicated the detection of a very early pregnancy loss.
“For some,” the researchers noted, “this experience brings the grief of a pregnancy loss” that otherwise may not have been recognized.
Unfortunately, there is little guidance for women who want to know if they are pregnant beyond testing kit instructions, said the paper’s corresponding author, Alexandra Sundermann, MD, PhD, assistant professor of Obstetrics and Gynecology in the Division of Quantitative and Clinical Sciences at Vanderbilt Health.
The women in the study were part of the Pregnancy Study Online (PRESTO), a preconception cohort study established and led by Lauren Wise, ScD, professor of Epidemiology at the Boston University School of Public Health.
To better understand pregnancy testing behaviors and their implications, Sundermann and Elizabeth Jasper, PhD, also an assistant professor of Obstetrics and Gynecology at Vanderbilt Health, analyzed data that the women recorded regarding the timing and frequency of their use of home pregnancy testing and individual test results.
The study, which ran from 2018 to 2024, found that patterns of testing varied widely. Nearly 9% of participants tested every day for nine days — four days before the date of their expected period and four days afterwards — even after receiving a positive result. Others tested only once.
A better understanding of current testing practices, Sundermann said, can inform the development of evidence-based, best practice recommendations for at-home pregnancy testing. To that end, she and her colleagues are continuing to study the effect of early testing on women’s mental health.
They also are developing an online tool that can help women understand more specifically their chances of getting a reliable test result by day of testing. “Our goal is to equip women with more information for making decisions about how — and when — to test at home,” she said.
Also listed as co-authors were Anna Marie Jukic, PhD, MSPH, from the National Institute of Environmental Health Sciences in Durham, North Carolina, and Kenneth Rothman, DrPH, from the Boston University School of Public Health.
The study was supported in part by National Institutes of Health grants R01HD086742 and K12AR084232, and by the National Science Foundation.
