A new blood test for pregnant women of a certain blood type could help thousands avoid unnecessary treatment.
The test has been recommended in draft guidance by the National Institute for Health and Care Excellence for mothers-to-be who are rhesus-D negative in order to identify the blood type of their baby.
Currently all women with this blood type are given an injection of anti-D immunoglobin to prevent problems in future pregnancies. But only those whose baby is rhesus-D positive actually need it.
Until now there has not been a reliable way of testing the rhesus status of an unborn child.
”This test may lead to better adherence as these women know that if they do not have anti-D prophylaxis there is a risk of problems”
It is estimated the new test, which was developed by the NHS Blood and Transplant organsiation, could spare around 40,000 women from unnecessary treatment and save the NHS more than £500,000 a year.
In addition it will help preserve limited stocks of anti-D immunoglobin, which is derived from donated human blood, and reduce potential risk of passing on diseases that cannot currently be screened for.
The test – called high-throughput non-invasive prenatal testing (NIPT) for fetal rhesus-D status – is performed during routine antenatal appointments.
It analyses DNA from the fetus, taken from the mother’s blood.
Currently the blood type of babies born to rhesus-D negative women is determined by testing blood from the umbilical cord after birth.
Knowing the blood type of both mother and baby is important to help avoid rhesus disease, a condition where antibodies in a pregnant women’s blood attack a baby’s blood cells.
Also known as haemolytic disease of the fetus and newborn, it affects about 500 babies each year in England and can cause stillbirths, disability or death from anaemia and jaundice.
The condition only occurs when a rhesus-D negative mother has had previous exposure to rhesus-D positive blood and developed an immune response meaning first pregnancies are not usually dangerous but there is a risk to subsequent babies.
Professor Carole Longson, director of health technology assessment at NICE, said the test would help mothers make an informed choice about whether to have anti-D immunoglobin treatment – known as anti-D prophylaxis.
“This may lead to better adherence as these women know that if they do not have anti-D prophylaxis there is a risk of problems in future pregnancies,” she said.