We used to think the premarital blood tests that were once mandatory in every state were a way to ensure each person’s blood type was compatible — and to make sure you two weren’t related. Apparently, neither was true.
Actually, the blood test was about public health, usually to monitor for rubella (German measles) and syphilis. Several states also screened for gonorrhea and tuberculosis, and previously ordered HIV tests, for those getting married. Today, Montana is the only state to still demand a blood test (for women only, to test for rubella).
A few states —Texas, Missouri, Illinois, and Louisiana — required HIV tests for all folks getting a marriage license in the 1980s or ’90s, but all determined premarital blood testing is an extremely ineffective way of reaching those at risk for HIV. Interestingly, a report in the Journal of the American Medical Association showed that of the 70,846 people tested in Illinois, only eight tested HIV-positive. The study estimated the cost of testing there to be $2.5 million (that’s $312,000 per each HIV-positive diagnosis). The number of marriage licenses also declined in Illinois but went up in surrounding states during that same time. Today, several states still offer HIV information to soon-to-be newlyweds.
Source: Mandatory Premarital Testing for Human Immunodeficiency Virus: The Illinois Experience, JAMA, 1990