An epidemiologic justification for genetic counseling in family planning.

To determine whether families with chronically ill children compensate by having additional children an analysis which was part of an epidemiologic study of 70 childhood conditons was done on a sample of 291 white mothers who were matched with controls according to the age of the mother at the time of the birth of the chronically ill child and the order of the birth in the family. An additional group of families with chronically ill children was analyzed to determine if the presence of a chronically ill child deterred parents from having additional children. The probability of genetic conditions occuring in another child in the same family was often as high as 10%. To determine if genetic conditions were a deterrent to additional pregnancies the sample was divided into 2 groups: one with genetic conditions likely to occur and the other with them unlikely to recur. The fertility of sample mothers declined by 42% after they became aware of the childs diagnosis compared with a 37% decline in the control families. The decrease in fertility rate among mothers of children with conditions that were likely to recur in other children was 59% contrasted to a decrease of 41% in the controls. This decrease resulted from the sharp reduction in births among 17 couples who reported that they had at least 2 children with the same conditon. Their fertility rate decreased by 70% after they became aware of the diagnosis whereas their controls dropped by 39%. The fertility rate of mothers of children with conditions unlikely to recur declined by 36% about the same percentage as their controls. Genetic counseling could help alleviate some of the problems that these families encountered. Findings suggest that parents do not compensate for a chronically ill child by having an additional child but conversely they do not inhibit pregnancy and continue to have children purposefully or unplanned as do the parents of normal children. It is felt that if parents were aware of the risks involved in transmitting genetic defects they would probably avoid pregnancy.