Intrauterine growth retardation in full-term newborn infants with birth weights greater than 2,500 g

The social determinants of infant mortality and birth outcomes in Western developed nations: a cross-country systematic review

Infant mortality (IM) and birth outcomes, key population health indicators, have lifelong implications for individuals, and are unequally distributed globally. Even among western industrialized nations, striking cross-country and within-country patterns are evident. We sought to better understand these variations across and within the United States of America (USA) and Western Europe (WE), by conceptualizing a social determinants of IM/birth outcomes framework, and systematically reviewing the empirical literature on hypothesized social determinants (e.g., social policies, neighbourhood deprivation, individual socioeconomic status (SES)) and intermediary determinants (e.g., health behaviours). To date, the evidence suggests that income inequality and social policies (e.g., maternal leave policies) may help to explain cross-country variations in IM/birth outcomes. Within countries, the evidence also supports neighbourhood SES (USA, WE) and income inequality (USA) as social determinants. By contrast, within-country social cohesion/social capital has been underexplored. At the individual level, mixed associations have been found between individual SES, race/ethnicity, and selected intermediary factors (e.g., psychosocial factors) with IM/birth outcomes. Meanwhile, this review identifies several methodological gaps, including the underuse of prospective designs and the presence of residual confounding in a number of studies. Ultimately, addressing such gaps including through novel approaches to strengthen causal inference and implementing both health and non-health policies may reduce inequities in IM/birth outcomes across the western developed world.

Structural violence, urban retail food markets, and low birth weight

This paper investigates urban retail food markets and health in Syracuse, New York. A structured observational analysis found that a majority of corner markets do not sell fresh produce or low fat dairy products, but conduct a lively business selling lottery tickets, cigarettes, and liquor. A comparison of census tracts with and without access to supermarkets that sell fresh produce and other healthy food found that pregnant women living in proximity to a supermarket had significantly fewer low birth weight births than other pregnant women regardless of income level.

Heterogeneity within Asian Subgroups: A Comparison of Birthweight Between Infants of US and Non-US Born Asian Indian and Chinese Mothers

OBJECTIVES

Birthweight distributions and proportions of low birthweight (LBW) are commonly used to assess the health of populations. However, the "population" is difficult to define due to differences by race, socioeconomic status, age distribution, and cultural identity. This study analyzes birth outcomes in two Asian subgroups to examine variation within the Asian population.

METHODS

Analysis of the 1998-2003 National Center for Health Statistics' natality file for 293,211 singleton births in Asian Indian and Chinese mothers compared birthweight distributions, mean birthweights, proportions of very low birthweight (VLBW) and moderately low birthweight (MLBW) infants, and the influence of maternal nativity on these outcomes. A multiple logistic regression analysis, stratified by maternal nativity, was done to control for established confounders of maternal age, marital status, education, and parity.

RESULTS

Maternal characteristics and birthweight distributions varied by race subgroup and nativity. Infants of Asian Indian mothers had a lower mean birthweight and higher proportions of VLBW and MLBW than Chinese. After controlling for differences in maternal characteristics, infants of US born Asian Indian mothers were more likely to be VLBW (AOR 1.87, 95% CI: 1.27-2.75) or MLBW (AOR 1.59, 1.39-1.82) than infants of US born Chinese mothers. Similarly, infants of non-US born Asian Indian mothers were more likely to be VLBW (AOR 2.13, 2.06-2.21) or MLBW (AOR 2.26, 2.18-2.35) then infants of non-US born Chinese mothers.

CONCLUSIONS

Our study demonstrates variation in birth outcomes by maternal race and nativity in two Asian subgroups. The heterogeneity within a single commonly used "population" is likely not limited to these two Asian subgroups, but is probably applicable to many populations in the United States. Analyses should try to account for these differences to ensure a more accurate representation of various populations in the US. The difficulty of defining a population by race adds to the complexity of examining disparities in birth outcomes.

Multiple mortality optima due to heterogeneity in the birth cohort: A continuous model of birth weight by gestational age-specific infant mortality

Birth weight and gestational age are both important predictors of infant survival. Covariate Density Defined mixture of logistic regressions (CDDmlr), a method that accounts for unobserved heterogeneity, has been applied to birth outcomes using birth weight alone. This paper investigates a CDDmlr model of birth outcomes that includes birth weight and gestational age. Applications to four birth cohorts, composed of all non-Hispanic singleton African/European American female/male live births in New York State from 1985-1988, are presented. Multiple birth weight by gestational age optimal (minimal) mortalities are observed in the birth weight by gestational age-specific mortality surface. Multiple optima have not been mentioned in the published literature, but they do appear in some published plots of birth weight by gestational age mortality. It is possible that misreporting of gestational age contributes to this phenomenon, but it cannot completely explain the locations of the local optima. The global optimum is associated with a "normal" fetal development subpopulation, while the local optima are due to a subpopulation that accounts for most low birth weight, intrauterine growth retarded, pre-term, post-term, and small for gestational age births, as well as, births with misestimated gestational ages. These two subpopulations have significantly different birth weight by gestational age-specific mortality surfaces. Consequently, the presence of multiple optima can be attributed to heterogeneity in the birth cohort. Comparisons of CDDmlr based on birth weight by gestational age and birth weight alone might statistically identify births with "erroneous" gestational age.