Rh Incompatibility & Group B Strep

Rh Incompatibility

Blood type is identified by two major components—a letter (A, B, AB, or O) and the Rh factor. If your blood contains the Rh factor, you are Rh positive; if it lacks this factor, you are Rh negative. Therefore, if your blood type is AB and your are Rh-negative, you are said to have AB-negative blood.

If an Rh-negative person receives Rh Positive blood, she will become sensitized and her body will produce antibodies to attack the foreign red blood cells. This is significant in pregnancy for an Rh negative woman, because if her mate is Rh positive, the child can be Rh positive. During amniocentesis or the delivery of the placenta, it is possible for the baby’s blood to come in contact with the mother’s blood. If this happens, the mother’s body will produce antibodies against the Rh-positive cells.

These antibodies will attack the Rh-positive blood cells and cause them to die. This disease is called hemolytic disease of the newborn. Since the sensitization does not occur until after the birth, the first baby is not affected, unless the woman was previously sensitized and not treated. If a woman is not treated and becomes pregnant again with an Rh-positive baby, the antibodies will cross the placenta and kill the fetus’s red blood cells.

To prevent hemolytic disease of the newborn, RhoGAM, an Rh-immune globulin, is administered, after the birth of an Rh-positive infant, as well as after a miscarriage, an abortion, or amniocentesis. It is also given at 28 weeks of pregnancy. RhoGAM acts by suppressing the specific immune response of Rh-negative individuals to Rh-positive red blood cells. Since the woman does not produce antibodies, subsequent pregnancies will not be affected, and the woman can give birth to healthy newborns in the future. Hemolytic disease of the newborn is rare since the development of RhoGAM.

Group B Strep

Group B streptococcal (GBS) infection is found in the genital area of up to 30 percent of healthy women. Most infected pregnant women show no signs of illness, but are at increased risk for kidney infections premature rapture of the membrane, preterm labor, and stillbirth. The biggest danger is to infants who become infected during birth. While not all infants become ill, those rare infants who do contract the infection can suffer serious complications. The factors that increase the risk if complications are prematurity, fever during labor, high levels of bacteria, and prolonged rupture of the membranes prior to delivery.

According to the Centers for Disease Control (CDC), a culture of the vaginal and rectal area to check for group B strep should be performed on all pregnant women at 35 to 37 weeks of pregnancy. Some facilities also perform a culture upon admission in labor. Women who tested positive during pregnancy with either the genital culture or urine culture, who previously had an infant with GBS, or who deliver before 37 weeks gestation should be treated during labor with antibiotics. Women who did not have a culture done or whose culture result is not known should be given antibiotics if they are less than 37 weeks pregnant, have had ruptured membranes for longer than 18 hours, or have a temperature of over 100.4°F (Fahrenheit). Treatment with antibiotics during labor has been shown to be highly effective in preventing complications in newborns if the antibiotics are administered 4 or more hours prior to delivery. If the infant is delivered less than 4 hours following the administration of antibiotics or shows signs of infection, a partial or full septic workup may be required. This may include blood tests, a spinal tap, chest X-rays, and/or intravenous administration of antibiotics. The CDC also recommends that all infant of treated mothers be observed for 48 hours after delivery.

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