EARLY CHILD HEALTH IN LAHORE, PAKISTAN .2. INBREEDING

The prevalence of consanguineous marriages was studied in 940 families belonging to four different socio-economic groups in and around Lahor e, Pakistan. The births occurring in these families from September 198 4 to March 1987 were also investigated for birth defects. The overall prevalence of consanguineous marriages was 46 %. The first cousin marr iages were most common (67 %), followed by the marriages between secon d cousins, 19 %. The prevalence of consanguineous marriages was clearl y associated with the socio-economic status of the study groups; 50 % of the marriages was related in the periurban slum, 49 % in the villag e, 44 % in the urban slum and 31 % in the upper middle class. The birt h defects were also more prevalent in the poorer areas, being highest in the periurban slum (17.7 %) followed by the urban slum (15.6 %) and then the village (14.8 %) and lowest in the upper middle class (12.3 %). Although: the frequency of both consanguinity and birth defects we re related with the socio-economic levels of the study groups, there w as no association between inbreeding and birth defects. Perhaps, delet erious recessive genes for birth defects have been ''bred out'', becau se of continuous inbreeding over generations in this population. There was a significant predilection of major birth defects in boys without clear sex linkage. The conclusion is that the rate of consanguineous marriages was high, especially in the poorer areas, but the relationsh ip between consanguineous marriages and birth defects was little or no ne. However, other child health indicators may be affected by consangu ineous marriages.