To the Editor.
—The findings by Cnattingius et al1 of increased risks of adverse perinatal outcomes with advancing maternal age in a population-based study of Swedish nulliparous women contrast with the results of our hospital-based study in the United States.2 The authors suggest that our findings are only characteristic of the population we studied, but that their results have ramifications for the United States. We take issue with this suggestion as there may be important cross-national differences that bear on the contrasting findings.Our study population comprised private patients who were predominantly white, married, college-educated, nonsmoking, and healthy. While we emphasized that our findings may not be generalizable to other sociodemographic groups, we also noted that this study population probably typifies urban women in the United States who postpone childbearing. According to a recent national report,3 49% of nulliparous women 30 years or older were college graduates.