Rh Sensitization During Pregnancy

If you are Rh-negative and pregnant

If you are an Reference Rh-negative Opens New Window woman and you have conceived with an Rh-negative partner, you are not at risk of Rh sensitization during pregnancy. (Most health professionals treat all Rh-negative pregnant women as though the father might be Rh-positive.)

If you are already sensitized to the Rh factor, your pregnancy will need to be closely monitored to prevent fetal harm. For more information on fetal and newborn treatment, see Reference Treatment Overview.

If you are unsensitized Rh-negative, treatment focuses on preventing Rh sensitization during pregnancy and childbirth. Reference Rh immune globulin (such as RhoGAM) is a highly effective treatment for preventing sensitization.

• To prevent sensitization from occurring late in the pregnancy or during delivery, you must have a shot of Rh immune globulin around week 28 of your pregnancy. This treatment prevents your immune system from making Reference antibodies Opens New Window against your fetus's Rh-positive red blood cells.
• Rh immune globulin injection is also necessary if you have had any vaginal bleeding or an obstetric procedure such as amniocentesis or external cephalic version.
• If your newborn is Rh-positive, you are given Rh immune globulin again within 72 hours of delivery. By preventing Rh sensitization from delivery, you are protecting your next Rh-positive fetus.
• If your newborn is Rh-negative, sensitization cannot happen, and no treatment is needed.

Rh immune globulin is also needed after a miscarriage, partial molar pregnancy, ectopic pregnancy, or abortion.

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