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No, rhesus factor affects everyone – it’s not about being black or white

Does a black woman expecting a baby with a white man risk miscarriage? 

The anxiety-inducing post has spread widely on Facebook.

“Here is a medical secret the white world hides from you,” the post begins. 

“Do you know that when pregnant by white men, most black women require a special shot to prevent their bodies from aborting their babies? Because of the Rhesus Factor found within over 90% of Caucasians.”

We put the claim under the microscope.

What is the rhesus factor?

According to the UK National Health Service (NHS), rhesus disease is caused if a woman has rhesus negative blood (without the rhesus antigen) and is exposed to rhesus positive blood (with the rhesus antigen), usually during pregnancy. 

If the father has rhesus positive blood, the baby may also be rhesus positive.

The next time the woman is exposed to rhesus positive blood, usually in a subsequent pregnancy because she is again carrying a rhesus positive baby, her blood cells may produce antibodies that attack the developing baby’s blood cells.

“If rhesus disease is left untreated, severe cases can lead to stillbirth,” the NHS says. In other cases, “it could lead to brain damage, learning difficulties, deafness and blindness” in the baby. This is unusual, as the treatment is usually effective.

An advisory by Penn Medicine, a hospital at the University of Pennsylvania in the US, says “about 85% of Caucasians are rhesus positive, while the percentage is even higher for African Americans, Asians, and American Indians”.

According to Blood Groups and Red Cell Antigens, a book by Laura Dean published in 2005 by the US National Centre for Biotechnology Information, 85% of white people are rhesus positive, while 92% of Africans are rhesus positive. 

‘Not about being white or black’

Africa Check asked Dr Ahmed Kalebi, a pathologist and the CEO of Lancet Group of Laboratories, about the post. He said it was inaccurate.

“It is not about being white or black, as rhesus factor is either positive or negative regardless of race and thus rhesus incompatibility can occur even among the same race and treatment may be required to manage abnormal intrauterine development,” Kalebi said.

“The Facebook post appears to oversimplify the matter and put a racial connotation to it, which is incorrect.”

Professor Walter Mwanda, a haematologist at the University of Nairobi, Kenya, also dismissed the claim. 

“There’s nothing like that on earth,” he said.

“It does not matter what the race of the person is. What matters is the rhesus status of the person affected. It affects everybody.” – Vincent Ng’ethe


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