Consistent with the decline seen in the early 1990s, the infant mortality rate in New York City continued to decrease over the past five years from 7.8/1,000 live births in 1996 to 6.7/1,000 in 2000, exceeding the Healthy People 2000 objective of 7.0 but still higher than the Healthy People 2010 objective of 4.5/1,000. The fetal death rate also declined during this period from 12.6/1,000 live births plus fetal deaths >20 weeks’ gestation in 1996 to 10.8/ 1,000 in 2000. However, despite the declines in infant mortality, racial/ethnic disparities persist, with the infant mortality rate and fetal death rate for black non-Hispanic women much higher than the rate for white non-Hispanic women.
Determinants of fetal and infant deaths include birth weight; maternal health and pregnancy care; alcohol, drug and tobacco use; infections; newborn and infant care; and socioeconomic status. It is important to analyze the relative contribution of these factors to feto-infant mortality to better target interventions to a particular community. To that end, the Perinatal Periods of Risk (PPOR) model, developed for the World Health Organization (WHO), can be used to analyze the contribution of various factors on feto-infant mortality. The model was originally used by the WHO and the Centers for Disease Control and Prevention (CDC) to monitor and investigate feto-infant mortality in developing countries. In recent years, it has also been applied to several populations within the United States.
The PPOR model helps guide the design and implementation of perinatal interventions. The model examines fetal and infant deaths by age at death (fetal, neonatal, postneonatal) and birthweight (500-1,499, >1,500 g). It then groups age at death and birthweight into four categories that identify where the problem that led to the death was likely to have arisen. The PPOR model groups fetal and infant deaths into the following categories:
a) fetus and infants weighing 500-1,499 g;
b) fetus weighing >1,500 g;
c) infants who died in the neonatal period and weighed >1,500 g; and
d) infants who died in the postneonatal period and weighed > 1,500 g.
Deaths in the above categories are hypothesized to be related to factors that have common mechanisms of action or common risk factors. Category “a”— labeled in the model Maternal Health/Prematurity— included deaths related to factors originating from poor maternal health and/or prematurity, conditions that often precede pregnancy or occur early in pregnancy, such as infections, hypertension, diabetes, cervical anomalies, smoking, and alcohol and drug use. Fetal deaths in category “b”—labeled Maternal Care—have survived early pregnancy loss and are thought to be affected by issues related to pregnancy care. Infant deaths in category “c”—labeled Newborn Care—are most often due to congenital anomalies, sepsis or pneumonia and could in some instances be avoided by better newborn care. Those infants in category “d”— labeled Infant Health in the model—have survived the neonatal period and die mainly of Sudden Infant Death Syndrome (SIDS), consequences of congenital anomalies, infections or injury. This categorization does not imply direct causal relationship but allows grouping in broad categories that differ in interventions needed to correct underlying risk factors and allows targeting of resources.
Once deaths are categorized, an overall feto-infant mortality rate is calculated and the relative contribution of each category to the overall rate is identified. The category(ies) that contributes most to the overall feto-infant mortality rate and where effective interventions exist are the area in which interventions are likely to have the greatest impact in the given community or group. The PPOR model is described in great detail elsewhere.
This paper examines fetal and infant deaths in a racially and ethnically diverse urban setting, New York City, using the PPOR model. Although the model has been used elsewhere, this study adds a new dimension by applying it to a racially and ethically diverse population where over one-third of the births are to Hispanic women, while a quarter are from women of African-American descent.