Higher rate of stillbirth at the extremes of reproductive age: A large nationwide sample of deliveries in the United States

Abstract

The purpose of this study was to assess the effect of maternal age on the rate of stillbirth in a large, nationwide sample of deliveries in the United States. Data were derived from the Nationwide Inpatient Sample for the years 1995 through 2002. With the use of ICD-9 codes, the rate of stillbirth was determined as a function of maternal age. Multivariate regression analysis was used to assess the effect of maternal age on the odds of stillbirth, with adjustment for multiple known risk factors for stillbirth. There were 5,874,203 deliveries that were identified for analysis. The unadjusted rate of stillbirth was elevated for teenagers and for women aged > or =35 years. In the multivariate analysis, compared with women 20 to 34 years old, women who were < or =19 years old were more likely to have a pregnancy outcome of stillbirth (odds ratio, 1.11; 95% CI, 1.08-1.14), as were women who were 35 to 39 years old (odds ratio, 1.28; 95% CI, 1.24-1.32) and women who were > or =40 years old (odds ratio, 1.72; 95% CI, 1.63-1.81). The extremes of maternal age are associated with an increased risk for stillbirth, even after adjustment for a large number of known predisposing conditions.