During your pregnancy, you'll be tested for a protein called the Rh factor. Even if you test negative for Rh, your partner will also need to be tested, and if he is Rh-positive then this combination might make your child Rh-positive. This condition could have serious health consequences for your little one, as your body may make antibodies against your baby's Rh-positive blood. To prevent this, you'll receive a shot of a substance called Rh immune globulin between your 28th and 29th weeks of pregnancy. You may also receive a shot after birth to protect future pregnancies.