People with positive Rh factors have positive blood types, whether A+, B+, AB+, or O+. People with negative Rh factors then have negative blood types, e. g. A-, B-, AB-, or O-. The majority of people have Rh positive factors. [4] X Trustworthy Source Mayo Clinic Educational website from one of the world’s leading hospitals Go to source
If you have a positive Rh factor, you can receive either Rh+ or Rh- blood during transfusions. If you have Rh- blood, you must receive Rh-. blood[5] X Research source (except in certain life-threatening emergencies when you might need to receive Rh+ blood).
Because people with positive blood types can possess either two positive Rh genes (Rh+/Rh+) or one positive and one negative (Rh+/Rh-), there can be instances where both parents have positive blood types but their children have negative blood types. [8] X Research source
Doctors test children’s blood through the back of their hands. [10] X Trustworthy Source National Health Service (UK) Public healthcare system of the UK Go to source If you feel like you might pass out, tell the medical professional. He/She can help you recline. [11] X Trustworthy Source National Health Service (UK) Public healthcare system of the UK Go to source You might feel a prick, sting, or mild pain when your nurse sticks you. After the test, you might bruise at the puncture site. This pain should not last long. [12] X Research source
It is likely that the lab will run tests to determine your ABO blood type as well during this time.
During your pregnancy, if you are Rh-, you will take blood tests to see whether your body is producing antibodies against Rh+ blood. The first will happen in your first trimester and the second will occur when you are 28 weeks pregnant. If no antibodies have developed, you will receive a shot of Rh immune globulin. This shot will prevent your body from producing harmful antibodies against your child. If your body has produced antibodies against Rh+ blood, you will not receive an immune globulin shot. Instead, doctors will keep a close eye on your baby as he/she develops. Either before or after his/her birth, your child might receive a blood transfusion. Once your baby is born, doctors can test his/her Rh factor. If your baby shares your Rh factor, you will need no further treatment. If you are Rh- negative, however, and your baby is Rh+, you must receive another immune globulin shot. [15] X Trustworthy Source American College of Obstetricians and Gynecologists Professional association of OB/GYNs focused on education and public outreat initiatives Go to source
