Determining the blood group and Rhesus (Rh) factor of both parents is a crucial routine test during pregnancy. Rhesus incompatibility, a potentially life-threatening condition, occurs when a woman with Rh-negative blood carries an Rh-positive baby. In this scenario, the mother's immune system may recognize the baby's Rh-positive red blood cells as foreign and produce antibodies against them.
This condition rarely affects a first pregnancy because the mother's immune system is usually exposed to the baby's blood only near the end of pregnancy or during childbirth. However, once antibodies develop, they can cross the placenta in subsequent pregnancies and attack the red blood cells of another Rh-positive baby, increasing the risk of severe complications.
Understanding the Rh Factor
The Rh factor is an inherited protein found on the surface of red blood cells. Individuals with the protein are Rh-positive, while those without are Rh-negative. Normally, maternal and fetal blood remain separate throughout pregnancy. However, a small amount of fetal blood can enter the mother's bloodstream during miscarriage, ectopic pregnancy, invasive prenatal procedures, abdominal trauma, falls, road traffic accidents, labour, or delivery. If the baby is Rh-positive, this exposure can trigger antibody production in an Rh-negative mother—a process known as sensitisation. Once sensitised, the antibodies remain in the mother's bloodstream and can affect future Rh-positive pregnancies if preventive treatment is not given.
Preventing Sensitisation with RhoGAM
Speaking with PT Health Watch, obstetrician and gynaecologist Qudus Lawal explained that the condition can be prevented through timely administration of Rh immunoglobulin, commonly known as RhoGAM. The injection prevents an Rh-negative woman's immune system from producing antibodies against Rh-positive blood. According to him, RhoGAM is routinely administered during pregnancy, usually between 28 and 32 weeks' gestation, after events that may expose the mother to fetal blood (such as miscarriage or invasive procedures), and within 72 hours after delivery if the baby is confirmed to be Rh-positive.
Mr Lawal noted that Rh-positive individuals naturally tolerate Rh-positive blood, whereas Rh-negative individuals can develop antibodies after exposure. Problems arise only when an Rh-negative woman becomes sensitised after exposure to Rh-positive fetal blood.
Possible Complications of Rhesus Incompatibility
If left unmanaged, Rhesus incompatibility can lead to serious health problems for the baby. Mr Lawal said these include severe fetal anaemia caused by destruction of red blood cells, jaundice after birth, and, in severe cases, pregnancy loss. Without prompt treatment, affected babies may develop complications associated with severe anaemia and elevated bilirubin levels.
Importance of Early Antenatal Care
Mr Lawal stressed that prevention begins even before pregnancy. He advised women planning to conceive to know their blood group and undergo preconception counselling where possible. He also highlighted the importance of early antenatal care, noting that routine blood group testing and antibody screening at the first antenatal visit allow healthcare providers to identify women at risk and provide appropriate preventive treatment. The specialist warned that once an Rh-negative woman becomes sensitised, RhoGAM can no longer prevent antibody formation.
“Being Rh-negative is not a disease,” Mr Lawal said. “It only becomes a concern if the necessary precautions are not taken.” He added that with regular antenatal care, appropriate monitoring, and timely administration of Rh immunoglobulin, the potentially life-threatening complications of Rhesus incompatibility can be effectively prevented.
