Infant Mortality Statistics Do Not Adequately Reflect the Impact of Short Gestation

Abstract

To determine the accuracy of National Center for Health Statistics cause-specific infant mortality data. The National Center for Health Statistics compiles these data by applying World Health Organization (WHO) selection rules to death certificate data. The WHO rules arrange medical entities into a hierarchical order and select a single underlying cause of death (ULCD). A comparison was made between ULCD assigned to a cohort of 335 infant death certificates by (1) a neonatologist panel, and (2) application of WHO selection rules by the Florida State Office of Vital Statistics (OVS). Among the 146 infants with birth weights 1500 to 4649 g, agreement between neonatologists and OVS was 88%, while among the 189 infants with birth weights 0 to 1499 g (very low birth weight), agreement was just 41%. Neonatologists selected short gestation as the underlying cause of death for 82% of very low birth weight infant records, vs 25% by OVS. Due to the application of specific WHO selection rules, OVS frequently selected immediate causes of death, such as "cardiac arrest," as the ULCD, even when the medical certifier had indicated short gestation as the ULCD. In vital statistics reports, many of these immediate causes are reported as "other respiratory conditions of newborn," or "all other perinatal conditions." WHO ULCD selection rules should be modified to allow short gestation to have a higher priority over immediate causes of infant death.