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Understanding Rh Factor: What You Need to Know During Pregnancy

Key Takeaways

  • About 15% of women are Rh-negative, meaning they lack the Rh protein on red blood cells—if their baby inherits Rh-positive blood from the father, immune incompatibility can develop.

  • First pregnancies are typically safe, but subsequent Rh-positive pregnancies carry higher risk as maternal antibodies from previous exposure can attack the baby's blood cells.

  • Untreated incompatibility can cause severe fetal anemia, hydrops fetalis (fluid buildup), brain damage, or stillbirth as maternal antibodies destroy the baby's red blood cells.

  • RhoGAM (Rh immunoglobulin) injections at 28 weeks and within 72 hours after delivery prevent antibody formation with over 99% effectiveness when given properly.

  • Additional RhoGAM shots are needed after miscarriage, amniocentesis, or any bleeding episodes during pregnancy to prevent sensitization from even small blood exposures.

When you're pregnant, your doctor will perform several tests to ensure the health of you and your baby. One of the most important tests is the Rh factor test. In this article, we'll explain what Rh factor is, why it's important during pregnancy, and how to manage Rh incompatibility.

What Is Rh Factor?

Rh factor is a type of protein found on the surface of red blood cells. If you have this protein, you're considered Rh positive. If you don't have it, you're Rh negative. About 85% of people are Rh positive, while the remaining 15% are Rh negative.

Why Is Rh Factor Important During Pregnancy?

Rh factor becomes crucial during pregnancy because it can affect the health of your baby. If you're Rh negative and your baby is Rh positive, it can lead to a condition called Rh incompatibility. This happens when your body produces antibodies that attack your baby's red blood cells, causing a serious condition known as Rh disease.

Understanding Rh Factor: What You Need to Know During Pregnancy

How Is Rh Incompatibility Managed?

If you're Rh negative, your doctor will closely monitor your pregnancy. Around the 28th week of pregnancy, you'll receive a shot of Rh immunoglobulin (RhIG). This medication prevents your body from producing antibodies that could harm your baby. You may need another dose after delivery.

If you develop Rh antibodies, RhIG won't be effective. In this case, your doctor will monitor your baby's health closely. Some babies may need a blood transfusion after birth or even while in the womb.

When Is the Rh Factor Test Done?

The Rh factor test is usually done during the first trimester of pregnancy. If you're Rh negative, you may need additional tests, such as an antibody screen, to check for Rh antibodies in your blood.

Situations That May Require Additional Rh Factor Testing

  • Vaginal bleeding during pregnancy

  • Amniocentesis or chorionic villus sampling (CVS)

  • Injury to the belly during pregnancy

  • Breech baby that requires external manipulation

  • Miscarriage, ectopic pregnancy, or abortion

If any of these situations occur, your doctor may give you a dose of RhIG to prevent Rh sensitization.

Remember, being Rh negative doesn't mean you can't have a healthy pregnancy. With proper monitoring and treatment, you can ensure the well-being of both you and your baby. If you have any concerns about Rh factor or your pregnancy, don't hesitate to talk to your healthcare provider.

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The Bottom Line

Rh incompatibility is completely preventable with properly timed RhoGAM injections, making routine first-trimester blood typing crucial for all pregnant women. The key is preventing initial antibody formation since once sensitized, future pregnancies remain at risk. If you have questions about your Rh status or pregnancy blood work results, Doctronic can provide quick answers and guidance.

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