A Thin Blue Line: The History of the Pregnancy Test Kit (review)

When a woman becomes pregnant, the placenta secretes a hormone known as human chorionic gonadotropin (HCG). Scientists have been aware of the presence of HCG in urine since the 1920s, but it took until the 1970s for researchers to develop a test sensitive and specific enough to enable women to confirm an early pregnancy at home. A Thin Blue Line: The History of the Pregnancy Test Kit provides an intriguing glimpse of some of the personalities and scientific research behind this medical and cultural milestone.

The Web site is sponsored by the National Institutes of Health (NIH) Office of History, and it is two NIH researchers, Judith Vaitukaitis and Glenn Braunstein, who get top billing. When they arrived at NIH in 1970 to work on reproductive endocrinology, a woman wanting "evidence" of pregnancy was compelled to go to her doctor's office for laboratory tests and a pelvic examination. Between the late 1920s and the 1950s, laboratory tests used in vivo bioassays in which animals were injected with a pregnant woman's urine and their responses were monitored. (Old television shows in which a wife told her husband that "the rabbit died" connoted both pregnancy and the animal sacrifice required for its detection.) Such tests were costly and time-consuming. In vitro bioassays, a cheaper and less time-consuming alternative, were not yet able to detect an early pregnancy. HCG is made up of subunits that are chemically indistinguishable from other hormones—specifically, the luteinizing hormone (LH) and the follicle-stimulating hormone (FSH); in vitro tests failed to distinguish between them, unless the pregnancy was advanced and corresponding HCG levels were high. Vaitukaitis and Braunstein's achievement was to create an in vitro radioimmunoassay sensitive to a beta subunit unique to HCG. The new assay could be used on early-morning urine collected days after a missed period. The scientists' findings were published in the American Journal of Obstetrics and Gynecology in 1972 and became the basis for the home pregnancy tests that first appeared on the U.S. market in 1978.

Much of the Web site chronicles HCG research at NIH and the recollections of Vaitukaitis and Braunstein. These are important, but it is unclear how many readers will be able to understand them. One of the site's drawbacks is its inability to translate scientific language into prose comprehensible to nonspecialists. Another is its internalist presentation of scientific discovery, which discounts the multiple sites, individuals, and contingencies that made this invention possible.

Still, A Thin Blue Line is a commendable addition to burgeoning interest in the making and diffusion of medical and consumer technologies. Perhaps its most fascinating feature is the reader-driven discussion of the impact of the home pregnancy test on women's lives. Run in collaboration with George Mason University's Center for History and New Media, the Web site's "Your Stories" section invites readers to share what the arrival of the home pregnancy test meant for them. Tales of trepidation, embarrassment, joy, and relief transport us back in time and remind us of the social and medical revolution that took place once laboratory inventions made their way out of doctors' offices and into the hands of ordinary people.