3 – It helps you understand your risks with pregnancy
Unlike the other ones on this list, this has nothing to do with your actual letters types, such as AB or O. Instead, this relates to what is known as the Rhesus (Rh) factor, which determines whether your blood type is negative or positive. If the baby’s Rh blood type is different from the mother’s, this could result in complications during pregnancy. For example, the mother’s body can end up building antibodies against the baby’s blood type, which could impact future pregnancies (it doesn’t affect the current pregnancy).