ABSENCE OF AN ENVIRONMENTAL-EFFECT ON THE RECURRENCE OF FACIAL-CLEFT DEFECTS

Background. The rate of of a broad range of birth defects may decrease among women who change residence after the birth of their first infan t, The aim of the present study was to determine the effect of changin g residence on the recurrence of congenital facial-cleft defects. Meth ods. We identified 4189 women who had had infants with facial-cleft de fects by linking a data base comprising the records of children with f acial clefts born between 1952 and 1987 with the Central Person Regist ry in Denmark, Among the 4189 mothers, 1902 each had additional childr en after the first child with a facial-cleft defect. A total of 2692 y ounger siblings were identified. We compared the proportion of infants with facial-cleft defects among the younger siblings between mothers who had changed municipalities or sexual partners and those who had no t. Results. Changing the municipality of residence did not decrease th e frequency with which facial-cleft defects recurred in younger siblin gs. Among the 907 infants of mothers who changed municipalities but no t partners, 29 (3.2 percent) had facial-cleft defects, as compared wit h 48 (3.4 percent) of 1425 infants of mothers who changed neither muni cipality nor partner (relative risk, 0.9; 95 percent confidence interv al, 0.6 to 1.5), However, a change of partner reduced the recurrence r isk significantly. Among 236 infants of mothers who changed partners, 1 (0.4 percent) had a facial-cleft defect, as compared with 77 (3.3 pe rcent) of 2350 infants of mothers who did not change partners (relativ e risk, 0.1; 95 percent confidence interval, 0.02 to 0.9). Conclusions . Recurrence of facial-cleft defects is not linked to the residence of the mother, but having a different partner reduced a woman's risk of having a second child with this defect.