Hematology: Controlling Rh Mismatch

Each year, at least 200,000 U.S. men with blood classified as Rh-positive marry women whose blood is Rh-negative. The mismatch poses no threat to the first child, but with the second there is an almost certain chance of miscarriage, stillbirth or brain damage. The only remedy with promise has been a transfusion, replacing the child's entire blood supply in the womb.

Medical researchers have now found a surer and simpler way to protect the second child by inoculating the mother during a crucial three-day period following the birth of her first child. Heretofore, the problem has been that during childbirth, the bloodstream of the Rh-negative mother is invaded by hundreds of thousands of the red blood cells of the child, each carrying the factor that makes it Rh-positive. During the next few weeks, her system reacts to the foreign cells by developing active antibodies that can then attack the blood of all subsequent children.

As devised by Dr. Vincent J. Freda and Dr. John G. Gorman of Columbia University, working with Dr. William Pollack of Ortho Research Foundation, the new technique is to vaccinate the mother immediately after the birth of her first Rh-positive child with a blood fraction containing other people's anti-Rh antibodies. These stifle development of a lifelong "active" immunity and in stead provide her system with a short lived "passive" immunity, and her system is far less likely to develop virulent antibodies. So far, reports Ortho, of 825 women treated with the fraction, only one became sensitized to the extent that a future baby would be endangered. Many have given birth to Rh-positive babies who showed no effects of the incompatibility.