The variables contained in the data sets are primarily concerned with perinatal outcomes and maternal health. A number of variables with respect to the social and economic status of the mothers and their families were also included (ie. Occupation, Marital status, Region). While all nine data sets are centered around these common themes and hold many variables in common, each data set has a unique combination of variables. The types of fields are wide-ranging but are primarily concerned with infant birth, maternal health, and socioeconomic status. The data analyzed in this study were taken from two sources, the Register of Birth and the Indoor Casebooks of the Edinburgh Royal Maternity Hospital. The bulk of the records are kept in the Medical Archives Centre, University of Edinburgh, in Edinburgh, although the Library of the Royal College of Physicians in Edinburgh holds the Indoor Casebook for 1844-71. In 1877 the hospital adopted a new form of taking case records, introducing discontinuity into the time series created for this study. The most significant change was a loss of some information about the social and economic backgrounds of the hospital patients. In years when fewer than 200 patients were admitted to hospital all cases were recorded. In other years a random sample of 200 patients were selected for analysis. Patient records were missing for 1852-53 and 1858-63. In all, 13,488 cases were chosen for preliminary analysis. The newborn weights and lengths in the sample are accurate to 91 grams and 0.6 centimeter at the 95 percent confidence level.