Birthweight curves in southern Israel populations.

With the aim of establishing a standard range of birthweights at different gestational ages for Jewish and Bedouin populations, we analyzed 5.5 years of computerized delivery files. Strictly confirmed gestational age was required in this study. This is necessary for proper diagnosis of growth abnormalities, such as growth retardation and macrosomia, for research purposes and for assessment of perinatal morbidity and mortality at a given gestational age. Percentile distributions of birthweights of 46,529 infants are presented. The mean birthweight of male infants was 3,238 g (SD 529 g) and of female infants was 3,117 g (SD 504 g). From week 36 to week 41 of gestation, infants of Jewish mothers were significantly heavier than infants born to Bedouin women, particularly in primiparous women. In both Jewish and Bedouin births, male infants were significantly heavier than female infants after the 36th week of gestation, by 130 g in the former and 127 g in the latter. Although the set of birthweight percentile curves of Jews and Bedouins was similar to the Colorado birthweight curve, some differences were found. At 41 and 42 weeks of pregnancy our infants were heavier and exceeded the standard, whereas at weeks 35 to 38 the standard exceeded the median weight of the Bedouin infants. The differences between our population curves and the commonly used Colorado standard curve emphasize the need for locally based and periodically updated infant birthweight data.