This treatment should be routinely offered to pregnant women

Andrea Sutcliffe

Currently about one third of NHS hospitals in England and Wales offer this treatment to rhesus negative mothers.

This means that they are missing a substance called D antigen on their red blood cells.

Most of the time this is not a problem, but it can cause difficulties during pregnancy if the baby is rhesus positive - which means they have D antigen on their blood cells.

In this instance, if blood cells from the baby get into the mother's bloodstream, her blood will react as if it is a foreign substance, and produce protective chemicals called antibodies.

This is not usually dangerous in a first pregnancy, but if subsequent babies are also rhesus positive these antibodies can cross the placenta and attack the blood cells of the unborn baby.

Usually, this results in a mild form of a condition known as haemolytic disease.

Serious cases

But in a small number of cases it can be more serious, and cause the baby to be stillborn, severely disabled or die after birth as a result of anaemia and jaundice.

Anti-D prophylaxis is a preventative treatment that can be given to rhesus negative mothers.

A substance called anti-D immunoglobulin is injected into the mother to prevent her producing antibodies to her baby's blood.

This in turn prevents the development of haemolytic disease in the unborn baby.

The National Institute for Clinical Excellence (NICE) has recommended that pregnant rhesus negative women should be offered this preventative treatment routinely, unless they already have antibodies to the D antigen in their blood.

The antibodies can be detected by a blood test at the beginning of pregnancy.

NICE has also recommended that health care professionals should explain the options available to rhesus negative mothers, so they can make an informed choice about treatment.

Numbers affected

Andrea Sutcliffe, NICE planning and resources director, said: "In England and Wales haemolytic disease of the newborn is responsible for the deaths of between 25 and 30 babies every year, and causes around 45 more to suffer developmental problems.

"The independent committee that advises us said this treatment should be routinely offered to pregnant women, but that there are circumstances in it may not be clinically necessary or cost effective.

"For example when the woman has opted to be sterilised after birth, where the father is rhesus negative, or where the woman is most unlikely to have another child"

Professor Steve Robson, an expert in foetal medicine at Royal Victoria Infirmary, Newcastle, told BBC News Online: "Although one is required to treat a lot of women to prevent a few cases of severe disease, providing the intervention is safe, it is reasonable that it is offered to all women."

Each year in England and Wales there are about 62,000 births of Rhesus positive babies to rhesus negative women.

About 500 of these babies develop haemolytic disease.

The most common time for a baby's blood cells to get into the mother's blood is at the time of birth.

However it can occur as the result of vaginal bleeding or having tests such as amniocentesis or chorionic villus sampling.