Birth Outcomes Across Three Rural-Urban Typologies in the Finger Lakes Region of New York

Birthweight and period of gestation are the 2 most important predictors of an infant's survival and subsequent health status.1-8 Infants born at low birthweight (LBW) or through preterm delivery (PTD) account for almost 70% of deaths within the first year of life8 and are at increased risk of developing both short-term and long-term health problems with implications for education and health care.7 An infant whose weight is less than the 10th percentile for gestational age is known as small for gestational age (SGA) and may be at particular risk of long-term morbidity.9 For these reasons, maternal, infant, and child health is one of 12 priority areas for the federal Office of Rural Health Policy's Rural Healthy People 2010 project, addressing objectives to improve birth outcomes in rural areas.10-12 Demographic, socioeconomic, health care, and cultural characteristics of rural and urban populations differ in many respects that could contribute to disparities in perinatal health status between populations. For example, rural women are more likely than urban women to live in poverty and to have lower levels of educational attainment,13 2 measures of low socioeconomic status that are associated with adverse birth outcomes.14,15 Further, rural women are more likely to be underserved by prenatal and obstetric care that can prevent pregnancy complications.12 A recent study hypothesized that unintended pregnancy may be more common among rural women, and the study identified specific rural barriers to parental communication about contraception including isolation and stigma.16 Unintended pregnancy can lead to poor birth outcomes through its association with risky behaviors such as prenatal smoking and unhealthy weight maintenance, higher prevalences of which have been demonstrated for rural women.17,18 Although New York State (NYS) is often identified with its cities, more than 3 million residents inhabit the vast majority of the state's land area outside of these cities.19 The 9 counties of the Finger Lakes region (Chemung, Livingston, Monroe, Ontario, Schuyler, Seneca, Steuben, Wayne, and Yates) exhibit tremendous variation in population density and in economic and health care indicators that could be expected to affect perinatal health in the region, including percent of population in poverty, educational attainment, and areas defined as medically underserved or as primary care shortage areas.20 Manufacturing remains the predominant employment sector in the region, accounting for almost 20% of the private workforce.21 In addition, health care is an important sector. This area includes 13 hospitals with maternity centers, delivering over 14,000 infants per year. Rates of most perinatal interventions and outcomes are similar to national rates. Multiple definitions for rurality in the US lead to ambiguity in defining rural populations, presenting a challenge for researchers interested in examining these potential disparities. Previous studies of rural-urban differences in birth outcomes used different typologies and area-level measures of rurality and yielded different results. In a national study by Larson et al of over 11 million singleton births between 1985 and 1987, residence in a nonmetropolitan county was not associated with increased risk of LBW or neonatal mortality at the national level or in most states, after controlling for demographic and biological risk factors.22 State-based studies defining all nonmetropolitan counties as rural generally showed no dramatic difference in birth outcomes23-26 due to the wide range of variation in health status within rural places and among population groups. Perinatal health disparities did appear in state-based studies in which zip-code level measures were used or remoteness was considered.22,27,28 In these studies capturing some of the heterogeneity of rurality, urban-adjacent rural women demonstrated better birth outcomes while women in more remote rural locations were at risk for poorer birth outcomes. To examine rural perinatal health, a researcher must choose the geographic area level and definition best suited to the population under study. The NYS Area Health Education Center recommends that zip code data “should be used whenever available” to reveal needs at the community level within the state.29 Available zip-code level typologies are the US Census Bureau's zip code tabulation areas (ZCTAs)30-33 and the zip code approximations for the Rural-Urban Commuting Area (RUCA) codes.30,34 Health researchers have developed additional typologies to meet their needs. For instance, Nesbitt et al created a typology in which rural residents are defined as those living within the primary service areas of a hospital designated as rural by the state Department of Health.35-36 Comparing the place of residence with the location of the hospital of delivery allows the determination of the proportion of all hospital births that occur in facilities outside a woman's local primary service area, classifying communities into low-, medium-, and high-outflow communities.35-36 Although this typology was not originally designed using zip codes, it can be applied to zip-code level data. Because the rurality of the same zip code may be classified differently across typologies, examining the same data across multiple definitions may yield different results. Farmer et al demonstrated this inconsistency with infant mortality data using 3 county-level residence measures: the federal Office of Management and Budget's dichotomous metropolitan/nonmetropolitan classification, a 5-level measure based on the population size of the largest community in each county, and a 9-level measure based on the size of the largest community in the county in combination with the contiguity of the county to a metropolitan county.37 The 9-level designation highlighted differences in infant mortality rates that were obscured in broader typologies, with higher rates of infant mortality in isolated rural counties and lower rates in rural counties that are adjacent to large population centers. In the current study, we compared 3 typologies of rurality to evaluate the hypothesis that populations of increasing rurality have rates of LBW, PTD, and SGA which are different from those of an urban population. In order to accomplish this goal, we 1) classified rurality of the NYS Finger Lakes region using 3 zip-code-level typologies and grouped births by zip code of maternal residence; 2) described the epidemiological characteristics of perinatal health and adverse birth outcomes for singleton births to rural mothers and compared them to those of urban mothers; and 3) compared results for rural births across typologies of rurality.