In connection with an investigation 1 of human fertility and the factors that influence it, based on the complete reproductive histories of 30,949 women delivered in hospitals during 1931 and 1932 and resident in selected large cities east of or on the Mississippi River, it became necessary to extract separately the material for New York City. For comparison with those data the material collected in the second largest city in the country, Chicago, seems particularly suitable. The samples from the two cities are of nearly the same size and in other respects closely similar.
All the original records and histories on which this study is based were obtained from the patients in hospital obstetric services by qualified medical persons (or in a few instances by trained nurses working under medical supervision).
It is my purpose in this paper to present such a comparison. Its interest arises from a number of