In a new study, researchers describe the first case in which preimplantation genetic diagnosis (PGD) - a test performed before implantation of a test-tube embryo - was used to avoid a serious newborn disease.

Hemolytic disease of the newborn occurs when the mother carries antibodies that attack a protein called rhesus D that may be found on the fetus’ red blood cells. Usually, the mother develops these antibodies during one pregnancy and then the problem occurs during a subsequent pregnancy. A counter-antibody therapy called RhoGAM is given to the mother and is usually, but not always, successful in preventing the problem.

With PGD, embryos are created outside the body with in vitro fertilization (IVF) and then tested for rhesus D. If the mother is carrying antibodies against rhesus D then only embryos that test negative for the protein are implanted into her womb. Thus, the mother’s antibodies never attack the baby’s blood cells.

At least, that’s how it works in theory, but until now, according to the researchers, it had never been done.

The case, reported in the medical journal Human Reproduction, involved a 27-year-old woman who was carrying rhesus D antibodies and sought pre-pregnancy counseling. The patient and her husband already had two children, the younger of whom was affected with hemolytic disease of the newborn.

To avoid this problem in the upcoming pregnancy, the couple agreed to assisted reproduction with the use of PGD to identify and implant only rhesus D-negative embryos, lead author Dr. Sean K. M. Seeho, from the University of Sydney in Australia, and colleagues note.

Pregnancy occurred and ultrasound testing showed no evidence of hemolytic problems. A healthy girl, confirmed to be rhesus D-negative, was born at 37 weeks.

“PGD was designed for detecting genetic defects, but, as this case demonstrates, may be used for couples at risk” for this hemolytic disease, the researchers state. “This provides an approach for selected couples to avoid the risk of having babies affected by hemolytic disease of the fetus and newborn.”

SOURCE: Human Reproduction 2005.