Carrier testing for certain genetic conditions is offered to pregnant patients and patients considering pregnancy. This type of testing determines if someone is at high or low risk to carry a genetic change (mutation) that could be passed on to a pregnancy. For most conditions tested, both parents must carry a change in the same gene for a pregnancy to be at increased risk. Blood carrier testing for cystic fibrosis and spinal muscular atrophy is offered to all pregnant and preconception patients. Other carrier testing may be offered based on ethnic background and family history.
The American College of Obstetricians and Gynecologists (ACOG) has an overview of carrier screening here: ACOG Carrier Screening FAQ