Dr. Greene, my Blood Group is B, Rh negative; my husband's Blood Group is A, Rh positive. We already have a child, but we want to have another one. My last blood analysis shows that my anticorps Anti-Rh were very high. The question is: Can I have another child?

Corina, your situation is both dangerous and precarious.

Every snowflake is different and each person is even more so! Each cell in our bloodstream carries our own genetic signature. A constellation of proteins on the surfaces of the cells allows our bodies to distinguish between our own blood and someone else's. These protein patterns are roughly divided into groups that we call blood types.

Not only are blood types different but some types of blood are incompatible with some others. The white blood cells in some types will perceive other types as enemies, attacking and destroying the other blood. This problem is most significant in people with Rh incompatibility.

People are called Rh-negative if they do not have the rhesus (Rh) protein on the surfaces of their blood cells. If Rh-positive blood cells get into the bloodstream of someone who is Rh-negative, the body of that Rh-negative person will see this as an enemy invasion.

Unprepared, the Rh-negative person will begin to make antibodies (what you call anticorps) against the foreign Rh protein. This first exposure is often not even noticed. The next time an exposure occurs, though, the body is primed to seek and destroy all Rh-positive blood cells. All-out war can occur inside an Rh-negative person’s body.

A terrible condition called hydrops fetalis can be the result of that war. Rh incompatibility produces a wide variety of outcomes. Sometimes only mild anemia and perhaps a little jaundice are the only signs there has been a conflict.

But sometimes the results are catastrophic. The first pregnancy is rarely a problem because blood is often not exchanged until the time of birth. But with each subsequent pregnancy, the risk for hydrops increases.

Hydropic babies are bloated, swollen, and pale. Enlarged hearts, livers and spleens are unable to perform their vital duties. The swollen lungs can make breathing impossible. Many hydropic babies are stillborn. Many die shortly after birth.

In 1963 an event occurred that began to change the story. Jorg Schneider, who was at the Freiburg University Hospital in Germany at the time, became the very first investigator to give pregnant, Rh-negative women a shot of Rh antibodies to prevent their immune systems from mounting their own response to Rh-positive cells.

The exact date of this achievement was August 9, 1963. One year later, Schneider reported that nine women, following delivery of Rh-positive children, did not develop Rh antibodies during subsequent pregnancies with Rh-positive fetuses.

Since then, prevention programs have been implemented in many countries around the world. In Great Britain, the number of deaths from hydrops has dropped 96% in the years since the prevention program began in 1970¹. This experience is typical.

By giving anti-D globulin (RhoGAM) to Rh-negative moms during and shortly after each pregnancy (including after miscarriages and abortions), 99% of mothers will not develop anti-Rh antibodies.² Unfortunately, about 1% still do.

Being Rh-negative is a recessive trait. This means that a person needs to have two negative genes to be Rh-negative and will always give one negative gene to any offspring.