Just like blood type, the Rh factor is also inherited from the parents; it can be either negative or positive. Rh factor simply means that a person’s blood has certain specific characteristics. The Rh factor is a protein found on the covering/surface of the red blood cells. If the Rh factor protein is present on the cells, then a person is Rh-positive, while if there is no Rh factor protein, the person is Rh- negative.

According to gynecologists, a big number of people are Rh-positive, although a small number of them may be Rh-negative, meaning they lack the Rh protein.

A positive or negative symbol after the blood type indicates their Rh factor.

Importance of testing for Rh factor

According to Yasin Uwimana, a Kigali-based gynecologist, testing for Rh factor is important for two major reasons.

He says if one is going to have blood transfusion, it is important because it helps in avoiding adverse reaction that can occur in case of incompatibility.

"Some people have these genes while others don’t have. Therefore, giving blood Rh to someone who doesn’t have it may cause a reaction which could be harmful to the receiver,” says Uwimana.

He says the other reason it’s vital to do the Rh test, especially for pregnant women, is because a mother who is Rh-negative may be married to a man who is Rh-positive, thus a high possibility of the baby becoming Rh-positive.

"The blood of the baby with Rh may get into contact with that of the mother who doesn’t have that Rh, in which case the mother might develop antibodies against that rhesus. This could affect future pregnancies,” he says.

According to online health portal, healthline.com, an unborn baby’s symptoms can range from mild to life-threatening. When your antibodies attack your baby’s red blood cells, hemolytic disease can occur. This means your baby’s red blood cells are destroyed.

"When your baby’s healthy red blood cells are destroyed, bilirubin will build up in their bloodstream. Bilirubin is a chemical that’s created from the breakdown of red blood cells. Too much bilirubin is a sign that the liver, which is responsible for processing old blood cells, is having trouble.

"The baby may have one or more of the following symptoms if their bilirubin levels are high after birth: yellowing of the skin and whites of the eyes, which is called jaundice, lethargy or low muscle tone.” These symptoms will subside once treatment for the Rh incompatibility is completed.

Uwimana notes that to prevent that risk, the mother should be given medication at 28 weeks of pregnancy, as well as within 72 hours after birth.

He adds that in case of an abortion, the drug should also be administered.

"This is because when a mother is Rh-negative and having an Rh-positive baby, during abortion, there may be contact of blood. When this happens, the mother develops the antibodies which may affect her future pregnancies,” he says.

Uwimana says when pregnant, it’s a must that one gets a blood test on their first prenatal visit during early pregnancy.

The blood test can be repeated between 24 and 28 weeks of pregnancy. This is done through amniocentesis, a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections.

Risks during pregnancy

According to Iba Mayele, a gynecologist at Doctors Plaza Kimironko, Kigali, any pregnant woman who is Rh-negative and is having a child with a father who is Rh-positive or with an unknown Rh status, is at risk for Rh incompatibility (this is where the mother is Rh-negative and the fetus is Rh-positive).

"If a mother is Rh-negative while father is Rh-positive, the fetus can inherit the gene of either parent. On the other hand, if both parents have the same Rh gene, the fetus will inherit that particular gene,” he says.

He notes that it’s always essential for any pregnant woman to be tested for Rh incompatibility to avoid risks that come about when the fetus and the mother have different Rh factors.

"Carrying different Rh protein factors between the mother and her fetus can be fetal during and even before birth,” he warns.

He explains that this is because the body of the mother (if she is Rh negative) will approach the Rh-positive protein from the fetus as something that is foreign and harmful.

"If blood cells from the baby cross the mothers bloodstream, which can happen during pregnancy, labour and delivery, the immune system of the mother will make antibodies against her fetus’ red blood cells,” Mayele says, explaining that antibodies are part of body’s immune system which destroy foreign substances.

He says mothers with Rh-negative blood type ought to be sensitised about their fetus.

"The bodies of mothers with this gene might send the same antibodies across the placenta to attack their fetus’ red blood cells because the placenta always connects the mother and the fetus. In order to carry oxygen to all parts of the fetus, there should be enough red blood cells. Without enough red blood cells, the fetus will not get enough oxygen, leading to serious illness,” he explains.

"Severe hemolytic anemia (where red blood cells are destroyed faster than the body can replace them) may occur, and even become fatal to the fetus.”

Just like Mayale, John Muganda, a gynecologist, says the placenta always connects the fetus and the mother, and can at times pass fluids to the fetus.

"Although during pregnancy, the mother and fetus do not share blood systems, a small amount of blood from the fetus can cross the placenta into the mother’s system. This can happen either during pregnancy, labour, or at birth,” he says.

He notes that bleeding during pregnancy and trauma to the abdomen during pregnancy are among the risk factors that can lead to Rh incompatibility if the mother is Rh-negative.

"It takes time for the body to develop antibodies, so firstborn children are usually not affected. However, if a mother was affected because of a miscarriage or an abortion, her first birth may be affected by Rh incompatibility,” says Muganda.

According to MeddlinePlus, Rh incompatibility can be prevented with the use of RhoGAM. Therefore, prevention remains the best treatment. Treatment of an infant who is already affected depends on the severity of the condition. Infants with mild Rh incompatibility may be treated with phototherapy using bilirubin lights. Intra-venous immune globulin may also be used.

For infants severely affected, an exchange transfusion of blood may be needed. This is to decrease the levels of bilirubin in the blood.