Thanks to home test kits, a woman can find out if she's pregnant in less time than it took to get that way. The Thin Blue Line, a new historical site from the National Institutes of Health (NIH), follows the invention of home pregnancy tests and examines their cultural impact. The key discovery came in the early 1970s, when NIH scientists devised the first reliable method to detect human chorionic gonadotropin, a hormone necessary to sustain pregnancy. The first tests based on the advance hit pharmacy shelves in 1978. But as the site's timeline shows, crude attempts to divine pregnancy date back more than 3000 years. For example, the ancient Egyptians put their faith in whether a woman's urine made wheat and barley seeds sprout. If neither kind of seed grew, she wasn't pregnant; if the barley grew, the child was a boy.