Early Pregnancy Tests

Sixty years ago early pregnancy tests seemed like a dream. At that time scientists did not have a firm understanding of the woman’s reproductive system. Then in the late 1940s Georgeanna Jones showed that human chorionic gonadotropin (hCG), a protein known to be present at the time of pregnancy, came from the placenta. Quickly the scientific community engineered a way to measure the amount of hCG in a female’s body. Refinements to those detection methods paved the way for development of present-day early pregnancy tests. The manufactured kits highlighted the transformation of test devices from an infant stage of development into a mature expression of scientific progress.

After Georgeanna Jones had identified human chorionc hormone (hCG) as an indicator of conception and pregnancy, then physicians had a way to request proof from the lab of a female patient’s pregnant condition. Still that test could not pick-up early signs of pregnancy, nor could it be performed in the privacy of the home. Thus the pharmaceutical industry chose to work on development of a way to conduct early pregnancy tests.

The first steps made toward creation of early pregnancy tests took place about 25 years ago. At that time researchers sought to learn more about the hormone known as hCG. Careful analyses, conducted by trained biochemists, showed that hCG, like all proteins, contained a chain of chemical units, with an amino group at one end of that chain and a carbon atom at the opposite end.

Supplied with that information, the researchers then proceeded to determine what part of the hCG molecule should be the target of a target-seeking antibody, a protein with the ability to identify the hCG molecule. In other words the researchers wanted to know, what part of the hCG molecule should be considered the antigen, the protein to which a testing compound could bind. By identifying the needed target, the pharmaceutical companies could then manufacture a suitable test kit.

A major move in the direction of usable early pregnancy tests came when the researchers found that the hCG molecule’s Carbon terminus was in the segment of the chain to which an antibody would need to bind. Biochemists then knew that they had to extract the C-terminus from each isolated hCG molecule, if they wanted to develop antibodies that could detect low levels of hCG in the bloodstream or urine.

At the earliest stages of a pregnancy, the placenta releases only a small amount of hCG into the bloodstream.  That is why the pharmaceutical industry knew that each of its early pregnancy tests had to be sensitive enough to detect even a low level of hCG. The test sensitivity could be enhanced through the use of the proper antibody. Selection of the proper antibody depended on identification of the target end of the hCG molecule.

Once the biochemists had identified the target end of the hCG molecule, then the immunologists could work on developing the proper antibody. Once the immunologists had developed the proper antibody, then a simple formula could direct the kit assembly. The antibody would need to be bound to a fixed section of the test kit. That antibody could then pick-up evidence that hCG existed in the test sample, i.e. evidence that hCG had entered the bloodstream. The most sensitive antibodies could be used in the early pregnancy tests.

At first only the women most eager to become pregnant used the early pregnancy tests. With time, however, larger numbers of young women counted on those tests to show whether or not they would soon be new mothers.