BIOLOGICAL AND SOCIAL TRAITS ASSOCIATED WITH TWINNING AMONG CAUCASOIDS AND NEGROIDS

The records of Caucasoid (589) and Negroid (142) mothers of twins, and of a control soup of mothers of singletons (1267 Caucasoids and 248 N egroids) born from 1984 to 1993 in the largest maternity hospital of C ampinas, SP, Brazil (Maternidade de Campinas) were investigated for th e following traits: type of hospital care, marital status, maternal ag e, occurrence of labor, type of delivery, parity, previous spontaneous abortions, gestational age, birth weight and birth length of twins an d singletons. The main conclusions were: 1) the proportion of women wh ose hospital and medical care expenses were covered by welfare program or who were indigent was significantly higher among Negroids than amo ng Caucasoids, but twinning was not associated with social class; 2) t he proportion of married women among Caucasoids was higher than among Negroids, and a greater proportion of Caucasoid mothers of twin births were married as compared to mothers of singletons; 3) Caucasoids and Negroids did not differ concerning mean maternal age, occurrence of la bor, type of delivery, rate of previous spontaneous abortions, and mea n gestational age; 4) when compared to women who bore singletons, moth ers of twin births were, on the average, almost two years older, and h ad a lower proportion of labor, a higher proportion of cesarean sectio ns, and a higher abortion rate, while the twins had a lower mean gesta tional age (three weeks) than singletons; 5) parity among Caucasoids w as lower than among Negroids, and in both races mothers of twin births had a higher parity than mothers of singletons; 6) twins had a lower mean weight and height at birth than singletons, males were slightly h eavier than females, and Negroids were slightly lighter at birth than Caucasoids.