SummaryAn analysis of 96% of Israeli live births, 1968–70, gives a mean birth weight of 3299 ± 543 g with 5·7% weighing less than 2500 g. The mean values increased from 3193 ± 510 g for first born to 3469 ± 604 g for tenth and subsequent births.There were significant differences between the mean birth weights, adjusted for birth order, of the different ethnic-origin groups. Infants of Jewish immigrants from North African countries weighed 3356 g followed by Christian Arabs (3337 g), Israeli-born Jews (3310 g), immigrants from Western countries (3303 g), Moslem Arabs (3251 g), Druze (3244 g) and immigrants from countries of Asia (3223 g).For the Jewish groups, the differences were diminished in the second generation of Israeli-born but those descended from Asian immigrants continued to be the lighter group.In order to determine the extent to which these differences are truly ‘ethnic’ further analyses of more homogeneous groups will be necessary taking into account a number of other demographic and socio-economic variables. (Summary in Hebrew, p. 58.)

SummaryThe influence of the country of origin of the father on mean birth weight of offspring of Jewish immigrants to Israel has been examined in an analysis of 98% of records of live births for the period 1968–70. The mean birth weight of infants born to parents from the same country (in-group marriages) was 3309 ± 570 g and that of infants whose parents came from different countries (out-group marriages) was 3289 ± 565 g: these differences are not significant.Infants born to immigrants from North African countries are heavier, and those born to immigrants from Asian countries lighter, than the Israeli mean. Apart from Algeria (whose immigrants have babies heavier than those from other North African countries) and India and Yemen (whose immigrants have babies lighter than those from other countries of Asia) there were no significant differences in adjusted mean birth weight by country of origin, within each continental group.Mean birth weight is determined by a combination of maternal and environmental factors, paternal factors having little effect.Analysis of birth weights of second and subsequent generations of Israeli-born, by origin of their grandparents, shows a fall in mean birth weight of those of North African descent and a rise in those of Asian descent, i.e. a tendency to approach an Israeli mean.(Summary in Hebrew, p. 164.)