Fetal deaths in the United States, 1997 vs 1991

Objective The purpose of this study was to examine the temporal change in fetal death risk in the US from 1991 to 1997, and to assess the extent to which changes in registration practices and labor induction have contributed to that change. Study design This was a cohort study of all singleton pregnancies 20 to 43 weeks of gestation in 1991 and 1997 in the US. Results From 1991 to 1997, the overall fetal death rate fell from 77.6 to 67.8 per 10,000 total births. However, fetal deaths at 20 to 22 weeks as a proportion of total births increased from 14.5 to 16.9 per 10,000. In a Cox regression analysis, the crude period effect (1997 vs 1991) at 40 to 43 weeks was 0.87 (95% CI 0.80-0.94), and remained virtually unchanged (HR 0.88, 95% CI 0.81-0.96) after adjustment for maternal sociodemographic, medical, and lifestyle risk factors. In ecologic (Poisson regression) analysis based on states as the unit of analysis, the crude period effect in non-Hispanic whites (RR 0.79, 95% CI 0.74-0.84) disappeared (RR 0.98, 95% CI 0.82-1.16) after adjusting for induction of labor. The effect of induction in blacks was limited to 42 to 43 weeks in those at high risk. Conclusion Increased registration is probably responsible for an increase in fetal death risk at 20 to 22 weeks of gestation, whereas the increasing trend toward routine labor induction at and after term appears to have reduced the risk of fetal death, especially among whites.