A marriage license is required in all 50 states. A blood test used to be one of the requirements for obtaining a marriage license, but many states have now dropped this requirement, and as of 2010, blood tests for certain diseases that could be passed on to children are required in only two states.
Syphilis
As of 2010, Mississippi requires a blood test to screen for syphilis. According to the Centers for Disease Control and Prevention, syphilis can cause severe health problems in an adult. But the disease can also be passed along to a baby, and can cause birth defects, stillbirths, seizures and even death. Both applicants for a marriage license in Mississippi have to complete this blood test.
Rubella (Measles) Immunity
Montana requires a blood test to detect rubella immunity, but only requires the female applicant to take a blood test. Rubella is a mild infectious disease that can go unnoticed in adults and even children, but can cause birth defects in developing babies.
Voluntary Blood Testing
The website Fitness Hub recommends a few blood tests for marrying couples that can offer peace of mind regarding each other and also when it comes to the health of future children. Those tests include hepatitis B, HIV, thallasemia and a blood group test to screen for other sexually transmitted diseases like herpes.


