Home and point-of-care pregnancy tests: a review of the technology.

Abstract

The earliest known pregnancy test, “If the veins within her arm beat against thy hand, thou shalt say ‘she is pregnant,’” dates to 1350 BC and reflects medicine’s longstanding interest in developing reliable methods to determine whether a woman is pregnant. Hippocrates in 400 BC described a method to diagnose pregnancy as follows: “Ingest honey in water: if pregnant, painful abdominal distention will result.” During the middle ages, “piss-prophets” used uroscopy to diagnose pregnancy. In 1200 AD, it was believed that milk would float on top of urine from a pregnant woman. In 1500 AD, coating of an iron needle with black spots when immersed in a woman’s urine was thought to indicate pregnancy. In 19th-century France, the presence of a “Kysteine pellicle” in urine was used to diagnose pregnancy.1 The first scientifically based pregnancy test, the A Z test, was initially described by Ascheim and Zondek in 1928. This bioassay, as well as subsequent tests introduced between 1929 and 1950, which used changes in ovarian estrogen production, weight, or blood flow; uterine, prostate, or seminal vesicle weight changes in rabbits or rats; or gamete production in toads, were based on the presence of human chorionic gonadotropin (hCG) in the urine of a pregnant woman.2 In 1957, the use of basal body temperature, which detects the rise in progesterone that triggers a rise in core body temperature occurring with ovulation and pregnancy, was introduced as a method for the detection of pregnancy. Starting in 1960, immunologic methods to detect hCG and hence diagnose pregnancy were introduced. The first antibody-based hCG assays used heme or latex agglutination to indicate the presence of immunoactive hCG in a pregnant woman’s urine. The radioimmunoassay for hCG was introduced in 1971 and the radioreceptor hCG assay in 1974.3 In 1976, the first home pregnancy test, based on hemagglutination inhibition, was introduced for sale in the United States. By the early 1980s, home pregnancy tests were based on an enzyme immunoassay or immunochromatography to detect hCG in urine.4 By 1988, monoclonal antibodies were introduced into home pregnancy testing. In the 1990s, the current generation of home pregnancy tests, which use monoclonal antibodies and visual labels in an immunochromatographic format, were introduced. These widely available consumer products cost pennies to manufacture, are simple to perform, provide results in under 5 minutes, and are able to reliably indicate pregnancy as early as 15 days after ovulation or 1 day after a missed menstrual period.