>>5349313Twenty-seven percent of Basques have O Rh negative blood. Rh negative blood in a pregnant woman can fatally poison a fetus that has positive blood. Since World War II, intervention techniques to save the fetus have been developed, but it is probable that throughout history, the rate of miscarriage and stillborn births among the Basques was extremely high, which may be one of the reasons they remained a small population on a limited amount of land while other populations, especially in Iberia, grew rapidly.
