Using an existing birth defects surveillance program to enhance surveillance data on stillbirths

Abstract

Background: Fetal death certificates (FDCs) are the main source of stillbirth surveillance data in the United States, yet previous studies suggest FDCs have incomplete ascertainment. In 2005, the Centers for Disease Control and Prevention (CDC) funded 2 pilot programs to determine the feasibility of expanding existing birth defects surveillance systems employing active casefinding methods to conduct surveillance of stillbirths. The objectives of this analysis were to: 1) estimate the completeness of ascertainment of stillbirths identified through one of the pilot programs, the Metropolitan Atlanta Congenital Defects Program (MACDP), and 2) compare the prevalence of stillbirths obtained through active casefinding (MACDP) with data available from FDCs.

Methods: Stillbirths in metropolitan Atlanta were independently ascertained by both FDC and MACDP in 2006 and 2008. Capture-recapture methods were used to estimate the total number of stillbirths in the surveillance area. The sensitivities for capturing stillbirths were estimated for FDCs, MACDP, and both sources combined. Prevalence estimates for each data source and for the combined data sources were calculated using a denominator of live births plus FDC-identified stillbirths.

Results: An estimated 1,118 stillbirths occurred in metropolitan Atlanta. MACDP captured 863 and FDCs captured 862. There were 198 stillbirths captured by MACDP and not reported by FDC, and 197 stillbirths identified by FDCs that were not initially captured by MACDP. The estimated sensitivities were 77.1 percent, 77.2 percent, and 94.8 percent for FDCs, MACDP, and both sources combined, respectively. The stillbirth prevalences for 2006 and 2008 using FDC data alone were 8.2 and 7.4 per 1,000 live births plus stillbirths, respectively, and 9.9 and 9.3 per 1,000 live births plus stillbirths, respectively, using both data sources combined.

Conclusions: Leveraging the resources of existing birth defects surveillance programs in combination with FDCs could improve population-based ascertainment of stillbirths.

Figure 1

Schematic used by MACDP for case classification of outcome MACDP: Metropolitan Atlanta Congenital Defects Program U/S: Ultrasound IUFD: Intrauterine fetal death FHTs: Fetal heart tones HR: Heart rate

Figure 2

Prevalence of stillbirths by data source, metropolitan Atlanta, 2006 and 2008 FDC: Fetal death certificates MACDP: Metropolitan Atlanta Congenital Defects Program

Figure 3

Prevalence of stillbirths with and without those resulting from induction of labor, metropolitan Atlanta, 2006 and 2008 *Excludes stillbirths occurring after induction of labor ** MACDP numerator includes stillbirths identified through FDC and linked (n=139) FDC: Fetal death certificates MACDP: Metropolitan Atlanta Congenital Defects Program