Blood Grouping 415 



into the mother's circulation, but at the time of labor and delivery 

 some mingling of bloods might occur. If the mother has had a 

 previous transfusion with Rh-positive blood, she will exhibit 

 antibodies. It is especially important, therefore, that Rh-negative 

 females be transfused with only Rh-negative blood from the time 

 of infancv through the child-bearing period. 



Most Rh difficulty arises during the second or the third 

 pregnancy when antibodies from the stimulation of the first fetus 

 pass through the placenta and destroy the cells in the developing 

 fetus. If the antibody titer is high, the fetus may die and be 

 expelled before the end of the normal gestation period, but if the 

 titer is relatively low, the child may be born alive and develop 

 erythrobkistosis fetalis, commonly called hemolytic jaimdice of the 

 newborn. The hemolytic destruction of the oxygen-carrying blood 

 cells may be severe enough to cause oxygen starvation of the child's 

 brain, with a mentally retarded child being the consequence. If 

 the condition is severe, the child may die unless a complete replace- 

 ment of blood is undertaken immediately after birth. Type O, 

 Rh-negative blood is given in such transfusions. 



From extensive studies involving large numbers of cases it has 

 been concluded that not more than one in ten pregnancies in 

 which Rh conditions are suitable for potential development of 

 hemolytic jaundice of the newborn (that is, an Rh-positive father 

 and an Rh-negative mother), does the condition actually occur. 

 The reasons for this are numerous and involve such considerations 

 as genetic inheritance of recessive characteristics, the amount and 

 the antigenicity of the red cells finding their way into the mother's 

 circulation, the titer of antibody produced by the mother, and 

 many other factors not clearly understood. 



QUESTIONS OF DISPUTED PARENTAGE 



There are occasions when questions of disputed parentage of 

 a child must be resolved, and the decision usually takes place in a 

 court of law. Infants are sometimes mixed in hospital nurseries, 

 and serological tests aid in deciding which child belongs to which 

 set of parents. Other cases arise in which a man is accused of 



