Data of twins born in Italy 1936-51

Abstract

Summary Data of 986 twins from the records of the Clinica Ostetrica of the University of Rome have been analysed as regards the distributions, means and standard deviations of mother's age, order of birth, birth weight and length of gestation time in groups of like and unlike sex. The chief characteristic of these data compared with similar data from English hospitals is the inclusion of cases of low birth weight and short gestation time. In the English data there are 9 cases out of 1137 of the group of weight under 680 g; in the present data there are 57 out of 1942 which fall into the lowest group under 500 g. Similarly in length of gestation the English data have only 2 cases out of 926 under 170 days compared with 33 of the Italian out of 945. The correlations between twin weights are respectively .8030 for like sex and .7604 for unlike sex; for weight and gestation period they are .3814 (like sex) and .3606 (unlike sex). The regression of weight on length of gestation runs as a smooth curve in accordance with previous findings. The mean weights for given gestation times are about the same as, or a little higher than, those for the English data. I am greatly indebted to Dr. Norma McArthur for giving me a copy of these data.