Did the rabbit test die?

Advertising for home pregnancy tests claims that they are at least 99% accurate when used on the first day of a missed period, but an evaluation of 18 brands yielded considerably worse results. (1) Following the instructions in the package insert, researchers tested each brand six times with five concentrations of human chorionic gonadotropin (hCG), the hormone produced by the placenta that is an early indicator of pregnancy. At an hCG level at which 95% of pregnancies should be detectable, none of the tests, when read at the suggested time (after 1-5 minutes), clearly indicated presence of the hormone; even at the highest hCG concentration tested, only 44% produced an indisputably positive result. The tests did better when they were read after 10 minutes and when questionable results were included, but only at the extended reading time did all 18 brands at least faintly detect the highest hCG level. Two brands gave false-positive results at the suggested reading time. The researchers suggest that "in fairness to the consumer," manufacturers of these products reassess their accuracy claims.

(1.) Cole LA et al., Accuracy of home pregnancy tests at the time of missed menses, American Journal of Obstetrics and Gynecology, 2004, 190(1):100-105.