How Accurate Are Fertility Tracking Apps?

Researchers analyzed more than 50 popular websites and smartphone apps that offer to predict a woman's "fertility window," or the days during a woman's menstrual cycle when she can become pregnant. They found that the fertility windows predicted by the apps and websites varied widely, and that many of these windows included days after ovulation, when the chances that sexual intercourse will result in pregnancy are close to zero. "Because there is no rigorous screening process in effect to vet th