Pregnancy Week by Week : Week 16 (part 4) - Rh Disease and Sensitivity

Rh Disease and Sensitivity

It’s important during pregnancy to know your blood type (O, A, B, AB) and your Rh-factor. The Rh-factor is a protein in your blood, determined by a genetic trait.

Everyone has either Rh-positive blood or Rh-negative blood. If you have the Rh factor in your blood, you are Rh-positive—most people are Rh-positive. If you do not have the Rh-factor, you are Rh-negative. Rh-negativity affects about 15% of the white population and 8% of the Black/African-American population in the United States.

An Rh-negative woman who carries an Rh-positive child could face problems, which could result in a very sick baby. If you are Rh-positive, you don’t have to worry about any of this. If you are Rh-negative, you do need to know about it.

Rh Disease. Rh disease is a condition caused by incompatibility between a mother’s blood and her baby’s blood. If you are Rh-negative, you can become sensitized if your growing baby is Rh-positive. Your baby may be Rh-positive only if your partner is Rh-positive. If you are Rh-positive and your partner is Rh-negative, you won’t have a problem.

Over 4000 babies develop Rh disease before birth every year. If you’re Rh-negative and your baby isn’t or if you have had a blood transfusion or received blood products of some kind, you might have a problem. There’s a risk you could become Rh-sensitized or isoimmunized. Isoimmunized means you make antibodies that circulate inside your system. The antibodies don’t harm you but they can attack the Rh-positive blood of your growing baby. (If your baby is Rh-negative, there is no problem.)

Cause of Problems. You and your fetus do not share blood systems during pregnancy. However, in some situations, blood passes from the baby to the mother. Occasionally when this happens, the mother’s body reacts as if she were allergic to the fetus’s blood. She becomes sensitized and makes antibodies. These antibodies can cross the placenta and attack the fetus’s blood. Antibodies can break down the baby’s red blood cells, which results in anemia in the baby and can be very serious.

With a first baby, if fetal blood enters the mother’s bloodstream, the baby may be born before the woman’s body can become sensitized. She probably won’t produce enough antibodies to harm the baby. However, antibodies stay in the woman’s circulation forever. In the next pregnancy, anemia can occur in the fetus because antibodies in the mom are already formed. If these antibodies cross the placenta, they can attack the baby’s red blood cells, resulting in anemia.

Preventing Problems. If you’re Rh-negative, you’ll be checked for antibodies at the beginning of pregnancy. If you have antibodies, you are already sensitized. If you don’t have antibodies, you’re unsensitized (this is good).

Rh-positive blood can mix with an Rh-negative woman’s blood, causing sensitization, in many ways. These include miscarriage, abortion, ectopic pregnancy, amniocentesis, chorionic villus sampling, PUBS or cordocentesis, blood transfusion, bleeding during pregnancy, such as with placental abruption, or in an accident or injury, such as blunt-force trauma to the uterus in an auto accident.

If you’re Rh-negative and are not sensitized, a treatment is available to prevent you from becoming sensitized. It is called RhoGAM and Rh immune globulin (RhIg)–they’re the same thing. RhoGAM is a product extracted from human blood. (If you have religious, ethical or personal reasons for not using blood or blood products, consult your physician or minister.) If your blood mixes with baby’s blood, RhoGAM keeps you from becoming sensitized. If you’re already sensitized, RhoGAM doesn’t help.

Your healthcare provider will probably suggest you receive RhoGAM around the 28^th week of pregnancy to prevent sensitization in the last part of your pregnancy. You’re more likely to be exposed to baby’s blood during the last 3 months of pregnancy and at delivery. If you go beyond your due date, your healthcare provider may suggest another dose of RhoGAM.

RhoGAM is given within 72 hours after delivery, if your baby is Rh-positive. If your baby is Rh-negative, you don’t need RhoGAM after delivery and you didn’t need the shot during pregnancy. But it’s better not to take that risk and to have the RhoGAM injection during pregnancy.

After delivery, if blood tests show a larger than normal number of Rh-positive blood cells (from baby) have entered your bloodstream, you may be given RhoGAM. The RhoGAM treatment is necessary for every pregnancy.

Rh Disease and Your Growing Baby. When Rh disease destroys a fetus’s blood cells, it can cause blood disease of the fetus or newborn. If your healthcare provider suspects fetal problems from Rh disease, amniocentesis and cordocentesis can help determine whether baby is developing anemia and how severe it is. These tests may need to be repeated every 2 to 4 weeks. Amniocentesis can also determine whether the fetus is Rh-negative or Rh-positive.

Ultrasound may be used to measure the speed of blood flowing through an artery in the baby’s head. This can help detect moderate to severe anemia but not mild anemia.

A blood test on you is done to help provide your medical team with information on the fetus. The test determines Rh status in the fetus, which may mean you won’t need amniocentesis in the future to determine this factor.

If your baby has a problem, there are actions that can be taken before birth. Babies have been treated with blood transfusions as early as 18 weeks of pregnancy.

8. Exercise for Week 16

You now know why you shouldn’t lie on your back to exercise after the 16^th week, so no more abdominal crunches. However, you can do a modified, pregnancy-friendly crunch. Sit on the floor in a crossed-leg position. Brace your back against the wall. Use pillows for added comfort. Exhaling through your nose, pull your bellybutton in toward your spine. Hold for 5 seconds, then inhale through your nose. Begin with 5 repetitions and work up to 10. Strengthens stomach muscles, and keeps lower back and spine strong.