The influence of the birth of a malformed child on the mother's further reproduction.

Births which occurred in Birmingham in 1964-70 were assembled into fraternities by computer linkage. By calculating the frequency with which one birth was followed by another and the interval between births the reproductive behavior of mothers after the birth of a malformed child was compared with that of all mothers, taking account of differences in maternal age, parity, and period of observation. It was found that malformations which resulted in stillbirth or early death were more frequently followed by another birth and that the interval to the following birth was shorter than usual. In this respect malformations did not differ in their effect from other causes of stillbirth and infant death. The birth of children were severe malformations who survived, however, acted as a slight deterrent to further reproduction. The malformation rate among children born after a malformation was double the usual rate; the recurrence rate was particularly high for neural tube defects, 5% of subsequent children being affected. In spite of this parents of children with central nervous system malformations were not deterred from further reproduction unless the affected child survived.