Why should I take the test?💡 

Rh factor is a protein that resides on the surface of red blood cells. If you have Rh factor, your status is Rh positive. If you don't have Rh factor, you're Rh negative.

If you're Rh negative, you might be Rh incompatible with your baby and produce antibodies to attack the baby's red blood cells if your baby's blood directly contacts with yours. You become Rh sensitized and require injection of a drug called Rh immune globulin to neutralize the antibodies and keep you from developing them.  

How is the test done?💉   

You can have blood tests at hospitals or clinics nearby. Special blood tests can also further be carried out to determine how much fetal blood has mixed with yours. 

TMI from Baby Billy👩‍⚕️: 

What are the chances that you and your baby are Rh incompatible?

Rh status is inherited usually from the father. In fact, your healthcare provider will assume you are Rh negative, just to be safe, and give you the shot if Rh immune globulin. There's no harm in getting the shot although you're Rh positive. 

How could your baby's blood and yours have contact?

Normally, during pregnancy, the placenta's blood is separated from yours. The placenta only receives oxygen and nutrients from your body but not red blood cells. Rh incompatibility is usually not a big deal as long as your blood doesn't intermingle with the baby's until labor.

Delivery: It's possible that your blood might have contact with the baby's during delivery. Hence, you should get a shot after delivery to prevent antibodies formation in a future pregnancy.

In the third trimester: Sometimes, your body can still develop Rh antibodies during the third trimester. When the doctor confirms antibodies being produced, you'll receive an injection at 28 weeks of pregnancy.

In other occasions: Your blood is mixed with your baby's if you have amniocentesis, chorionic villus sampling (CVS) test, an abortion, a miscarriage, or an injury in your abdomen. An ectopic pregnancy, vaginal bleeding and a stillbirth also promote this blood aggregation. 

How does the shot of Rh immune globulin prevent antibodies development?

The shot of Rh immune globulin functions according to passive immunization. It consists of a small dose of antibodies that kill Rh positive blood cells in your system to refrain your body from developing its own antibodies. You need to get the shot no more than 72 hours after any potential contact with your baby's blood. Your baby is then protected for 12 weeks. If the doctor notices the smallest sign of possible mixture, you'll be administered the second shot if necessary.  

You'll get the injection in the muscle of your arm or buttocks. The shot is safe and has no side effects for your baby despite his blood type. 

What happens if antibodies keep developing?

The antibodies that your body produces can cross the placenta, attack the Rh factor in your baby's Rh positive blood cells as if they are foreign substances, and destroy his blood, resulting in anemia. Severe conditions called hemolytic disease of the fetus (HDFN) can develop into more lethal complications such as jaundice, congestive heart failure, or even death.

However, the doctor can monitor your baby's red blood cells using Doppler ultrasound and amniocentesis. If your baby is doing well despite your Rh negative, you might be able to carry him without defects. After birth, the baby requires blood transfusion to replace all diseased Rh positive blood cells with healthy Rh negative blood cells, stabilizing the quantity of red blood cells and preventing further damage of antibodies.

The return of the Rh factor is just a matter of time. By the time it is present again, your baby's red blood cells will be Rh positive again, but the vigorous antibodies are long gone.