History

image:JanSteen-Doctor'sVisit(1658-1662).jpg.
Lubsen-Brandsma, M.A. (1997). Jan Steen's fire pot; pregnancy test or gynecological therapeutic method in the 17th century?. Ned Tijdschr Geneeskd, 141(51), 2513–7. Retrieved 2006-05-24.
"The Doctor's Visit." (n.d.). The Web Gallery of Art. Retrieved 2006-05-24.]] The ancient Egyptians watered bags of wheat and barley with the urine of a possibly pregnant woman. Germination indicated pregnancy. The type of grain that sprouted was taken as an indicator of the fetus's sex. Hippocrates suggested that a woman who had missed her period should drink a solution of honey in water at bedtime: resulting abdominal distention and cramps would indicate the presence of a pregnancy. Avicenna and many physicians after him in the Middle Ages performed uroscopy, a nonscientific method to evaluate urine.

Selmar Aschheim and Bernhard Zondek introduced testing based on the presence of human chorionic gonadotropin (hCG) in 1928. Early studies of hCG had concluded that it was produced by the pituitary gland. In the 1930s, Georgeanna Jones discovered that hCG was produced not by the pituitary gland, but by the placenta. This discovery was important in relying on hCG as an early marker of pregnancy. In the Aschheim and Zondek test, an infantile female mouse was injected subcutaneously with urine of the person to be tested, and the mouse later was killed and dissected. Presence of ovulation indicated that the urine contained hCG and meant that the person was pregnant. A similar test was developed using immature rabbits. Here, too, killing the animal to check her ovaries was necessary. An improvement arrived with the frog test, introduced by Lancelot Hogben, which still was used in the 1950s and allowed the frog to remain alive and be used repeatedly: a female frog was injected with serum or urine of the patient; if the frog produced eggs within the next 24 hours, the test was positive.

Direct measurement of antigens, such as hCG, was made possible with the invention of the radioimmunoassay in 1959,. Radioimmunoassays require sophisticated apparatus and special radiation precautions and are expensive. In the 1970s, the discovery of monoclonal antibodies led to the development of the relatively simple and cheap immunoassays used in modern home pregnancy tests.

Modern tests

The test for pregnancy which can give the quickest result after fertilisation is a rosette inhibition assay for early pregnancy factor (EPF). EPF can be detected in blood within 48 hours of fertilization. However, testing for EPF is expensive and time-consuming.