When Does a Child Get a Rhesus-Negative Blood Type?

When Does a Child Get a Rhesus-Negative Blood Type?




A child with Rhesus-negative blood -- more commonly called Rh-negative blood -- lacks the Rh-factor, a protein located on the surface of red blood cells, according to the American Pregnancy Association. People with this protein have Rh-positive blood, while those without it have Rh-negative blood. But having Rh-negative blood is not a disorder. The Tech Museum of Innovation reports that there is some scientific evidence indicating that those who are Rh-negative may have greater protection against some conditions. However, a woman with Rh-negative blood may experience potentially serious complications during pregnancy if she does not receive prompt medical attention before the baby's birth.

Rh-Negative Inheritance

For a child to have Rh-negative blood, he needs to have inherited two Rh-negative genes: one from his father and one from his mother. According to the Lucile Packard Children's Hospital at Stanford, a couple can have a child that lacks the Rh-factor only if both are Rh-negative or if both carry one recessive Rh-negative gene. People with any of the major blood types -- A, B, O or AB -- can be born Rh-negative. According to the American Pregnancy Association, approximately 15 percent of the population has Rh-negative blood.

Impact on Health

A child who has Rh-negative blood will not suffer from health problems directly caused by her lack of the Rh-factor, assures the March of Dimes. Having this blood type is simply a trait, similar to having brown hair or freckles. The Tech Museum of Innovation, which is supported by the Stanford School of Medicine's Department of Genetics, points out that those who have Rh-negative blood appear to have a higher resistance to the deadly parasite Toxoplasma than Rh-positive people. Geneticists theorize that Rh-negative blood may be an adaptation that has evolved to help protect against parasites and viruses, although more research is needed.

Possible Dangers

The only danger associated with Rh-negative blood is Rh disease, a condition that occurs when a woman with Rh-negative blood conceives a child who is Rh-positive because the child has inherited the dominant Rh-positive gene from his father. The Lucile Packard Children's Hospital reports that in Rh disease, the mother's body develops antibodies that destroy the baby's red blood cells, causing liver and spleen engorgement, anemia and jaundice. In severe cases, the condition can result in severe jaundice, brain damage, deafness, seizures or premature death. Rh disease does not develop if the mother is Rh-positive and her baby is Rh-negative.

Prevention

The key to preventing Rh disease is early detection, reports the Lucile Packard Children's Hospital. Women who receive prenatal care during the early stages of their pregnancy are tested for the Rh factor. If their blood is Rh-negative, they can be given Rh immunoglobulin, or Rhlg, a blood-like product that inhibits any antibodies that the mother's body produces from destroying her baby's Rh-positive blood cells. Most Rh-negative women receive Rhlg injections at the 28th week of pregnancy, as well as after any event that may allow contact between her blood and her child's blood, including an amniocentesis or trauma to the abdomen.

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