I Didn’t Know That . . .

Q: How accurate are home pregnancy test kits?

A: That depends on who is using them, according to researchers from Duke University. Manufacturers generally claim that the kits are 97% to 99% accurate, but the Duke team obtained worse results. The researchers combined data from five studies on 16 different kits. They reported in the September/October Archives of Family Medicine that when volunteers used the kits on urine samples collected by researchers in those studies, the tests were 91% accurate overall. But when the tests were performed by women on their own urine at home, the accuracy plunged to 75%. Although the kits advertise that they can be used as soon as nine days after a missed menstrual period, the Duke team found that the highest accuracy was obtained when women waited at least two weeks.