Mar 09 2017
This is the fifth and last part of my Injection of Optimism into Biomedical Research Series. I’m getting back to the babies on this one! In Part 1, I talked about the success of newborn screening programs, here I will be discussing a prenatal public health intervention that has saved and helped millions of babies worldwide.
The Rh protein complex is embedded in the membranes of red blood cells. Most individuals are Rh positive (Rh+), which means that their Rh complex contains a specific protein (the RhD antigen); individuals without that protein are Rh negative (Rh-). Approximately 15% of Caucasians, 7% of blacks, and 1% of Asians are estimated to be Rh-. Blood types are generally denoted by a shorthand reporting the ABO blood group and Rh status. For example, an individual who has an ABO blood group of B and is Rh- is often denoted as “B-.” The Rh type is inherited in a recessive manner, so that a child who is Rh- must have two Rh- parents, but a child who is Rh+ may have two Rh+ parents or one Rh+ and one Rh- parent.
Problems can result if an Rh- woman is pregnant and carrying an Rh+ baby. In that case, the woman’s body may create antibodies to the RhD protein in the baby’s blood. These antibodies can destroy the baby’s red blood cells, leading to severe anemia or even death. This is called “Rh incompatibility” and generally occurs after the first pregnancy, since the first baby is usually born before the development of too many antibodies. In 1960, Rh incompatibility and the resulting hemolytic disease of the newborn (erythoblastosis fetalis) was estimated to result in 10,000 stillborn babies and even more babies who were affected and generally expected to recover after blood transfusions. In 1968, two clinical trials showed that injection of the anti-Rh gamma globulin (RhoGAM) after the delivery of an Rh+ baby by an Rh- woman will prevent problems with later pregnancies. Women who are at risk of Rh incompatibility now generally receive the RhoGAM shot at 7 months and within 72 hours of delivery, as well as in the case of miscarriage or bleeding during pregnancy.
Given that Rh incompatibility used to lead to many cases of perinatal death and illness and is now a rare concern if the RhoGAM shot is appropriately administered, this is a major public health victory. I hope this series as a whole will help renew your optimism and sense of wonder in biomedical research and science in general. Now let me get back to writing that grant proposal…