Medicines for Haemolytic disease of the fetus and newborn

What it is

Haemolytic disease of the fetus and newborn (HDFN) is a condition in which a pregnant woman’s immune system produces antibodies that cross the placenta and attack (destroy) the red blood cells of her baby, before or after birth. The best-known form is rhesus (Rh) disease, which can occur when the mother’s blood group is rhesus negative (RhD negative) and the baby is rhesus positive (RhD positive) — a difference inherited from the father. If the mother’s immune system is exposed to the baby’s rhesus-positive blood (for example during birth, or certain events in pregnancy), it can become "sensitised" and produce antibodies against the rhesus factor; while this does not usually affect that first pregnancy, in a subsequent rhesus-positive pregnancy these antibodies can cross the placenta and attack the baby’s red blood cells. (HDFN can also, less commonly, be caused by other blood group differences.) The destruction of the baby’s red blood cells can cause anaemia (a low level of red blood cells) in the baby, and, after birth, jaundice (from the breakdown of red blood cells); in more severe cases, it can cause more significant problems for the baby before or after birth. A very important and reassuring point is that rhesus disease is now largely preventable and much less common than in the past, thanks to a treatment given to rhesus-negative mothers: an injection of anti-D immunoglobulin, given during pregnancy and after birth (and after certain events) where appropriate, which prevents the mother’s immune system from becoming sensitised, and so prevents the condition developing in future pregnancies. Pregnant women are tested for their blood group and for relevant antibodies as part of routine antenatal (pregnancy) care, which allows rhesus-negative women to be offered anti-D, and allows monitoring where antibodies are present. Where HDFN does occur or is a risk, the pregnancy and baby are monitored, and treatment — such as treating the baby before birth (for example a blood transfusion to the baby in the womb in severe cases) or after birth (such as treatment for jaundice with phototherapy, or a blood transfusion) — is given as needed by specialists, and most babies do well with appropriate care. The key messages are that HDFN is where a mother’s antibodies attack her baby’s red blood cells (often related to blood group differences, classically rhesus), that it is now largely prevented (particularly rhesus disease, by anti-D), and that it is managed with monitoring and treatment where needed.

How it is treated

Haemolytic disease of the fetus and newborn is now largely prevented (particularly rhesus disease, through anti-D), and, where it occurs or is a risk, managed with monitoring and treatment by specialists; routine antenatal testing underpins prevention and management. Prevention is a major success story: as part of routine antenatal (pregnancy) care, pregnant women are tested for their blood group (including whether they are rhesus negative) and screened for relevant antibodies. For rhesus-negative women, anti-D immunoglobulin is offered — given during pregnancy and after birth (and after certain events in pregnancy that could cause exposure to the baby’s blood, such as bleeding or procedures) where appropriate — which prevents the mother’s immune system from becoming sensitised and producing antibodies, thereby preventing rhesus disease in future pregnancies; this has greatly reduced the condition. Where a woman is already sensitised (has developed the relevant antibodies), anti-D no longer prevents the problem, so the focus shifts to monitoring and managing the pregnancy and baby: the pregnancy is monitored by specialists (for example, monitoring the antibody levels, and assessing the baby for anaemia, including with specialised scans), so that any problems in the baby can be detected and managed. Where the baby is affected, treatment is given as needed and is tailored to the severity: before birth, for a baby who is becoming significantly anaemic, treatment can include a blood transfusion given to the baby in the womb (intrauterine transfusion), carried out by specialists, which can be life-saving in severe cases; after birth, a baby with HDFN may need treatment for jaundice (such as phototherapy — light treatment — which is common and effective) and, in some cases, treatment for anaemia (such as a blood transfusion) or other treatments, provided by neonatal specialists. With modern prevention, monitoring, and treatment, most babies do well. The care is provided by obstetric and neonatal specialists, with close monitoring and individualised treatment. Because prevention (through anti-D and routine testing) and monitoring are so effective, the emphasis for most women is on attending routine antenatal care (which includes the blood group and antibody testing) and, for rhesus-negative women, accepting anti-D as offered, which prevents the condition. The reassuring messages are that HDFN, and particularly rhesus disease, is now largely prevented through anti-D and routine antenatal testing, that where it occurs or is a risk it is managed with monitoring and effective treatment (such as transfusion before birth in severe cases, and treatment for jaundice or anaemia after birth), and that most babies do well with appropriate specialist care; so attending routine antenatal care and, for rhesus-negative women, having anti-D as offered, along with specialist monitoring and treatment where needed, are the keys to preventing and managing the condition.