Consanguinity and its effect on fetal growth and development: a south Indian study.

The effect of consanguinity on fetal growth and development was studied in 3700 consecutive births (live and stillborn); 26% of the total births were to consanguineous couples. Hindus had a higher frequency of consanguineous marriages, uncle-niece unions being the commonest type, whereas Moslems preferred first cousin marriages. The incidence of congenital malformations was 39.1/1000 births with a significantly higher incidence among the consanguineous group (8.01%) as against the nonconsanguineous group (2.42%) (p less than 0.001). The incidence of malformations was higher in the uncle-niece matings (9.34%) compared to the first cousin marriages (6.18%) (p less than 0.01). Malformations of major systems were significantly more frequent among the consanguineous couples, whereas malformations of the eyes, ears, and skin did not show any significant effect of consanguinity. Stillbirth rates were significantly higher in the consanguineous group, irrespective of the mother's socioeconomic status, and were higher in uncle-niece matings compared to first cousin and beyond first cousin unions in both the poor and middle/upper class. A significant decrease in the mean birth weight and head circumference of babies born to consanguineous parents was noted in both the poor and middle/upper socioeconomic class. The mean length was less in babies born to consanguineous parents belonging to the poor social class only.