Trends in Stillbirth by Gestational Age in the United States, 2006-2012

Abstract

Objective: To evaluate stillbirth trends by gestational age.

Methods: National Center for Health Statistics' fetal death and live birth data files were used to analyze the 2006 and 2012 cohorts of deliveries and compute gestational age-specific stillbirth rates at 20 weeks of gestation or greater using two methods: traditional (eg, stillbirths at 38 weeks of gestation/live births and stillbirths at 38 weeks of gestation) and prospective (stillbirths at 38 weeks of gestation/number of women still pregnant at 38 weeks of gestation). Changes in rates and in the percent distribution of stillbirths and live births were assessed.

Results: In 2006 and 2012, the stillbirth rate was 6.05 stillbirths per 1,000 deliveries. There was little change in the percent distribution of stillbirths by gestational age from 2006 to 2012. However, the percent distribution of live births by gestational age changed considerably: births at 34-38 weeks of gestation decreased by 10-16%, and births at 39 weeks of gestation increased by 17%. Traditionally computed stillbirth rates were unchanged at most gestational ages, but rose at 24-27, 34-36, 37, and 38 weeks of gestation. However, rates were influenced by decreases in births at those gestational ages; the pattern of stillbirths by gestational age was unchanged. In contrast, there were no differences in prospective stillbirth rates at 21-42 weeks of gestation.

Conclusion: The lack of change in prospective stillbirth rates from 2006 to 2012 suggests that preventing nonmedically indicated deliveries before 39 weeks of gestation did not increase the U.S. stillbirth rate.

Level of evidence: II.

Figure 1

Percent distribution of stillbirths and live births by gestational age, United States, 2006 and 2012. Data from the Centers for Disease Control and Prevention/National Center for Health Statistics, National Vital Statistics System.

Figure 2

Prospective stillbirth rate by single weeks of gestation, United States, 2006 and 2012. The prospective stillbirth rate is the number of stillbirths at a given gestational age per 1,000 live births and stillbirths at that gestational age or greater. Data from the Centers for Disease Control and Prevention/National Center for Health Statistics, National Vital Statistics System.

Figure 3

Prospective stillbirth rate by single weeks of gestation and race/ethnicity, United States, 2006 and 2012.The prospective stillbirth rate is the number of stillbirths at a given gestational age per 1,000 live births and stillbirths at that gestational age or greater. Data from the Centers for Disease Control and Prevention/National Center for Health Statistics, National Vital Statistics System.