Race and the inheritance of low birth weight

Racial Disparities in Associations between Neighborhood Demographic Polarization and Birth Weight

Neighborhood demographic polarization, or the extent to which a privileged population group outnumbers a deprived group, can affect health by influencing social dynamics. While using birth records from 2001 to 2013 in Massachusetts (n = 629,675), we estimated the effect of two demographic indices, racial residential polarization (RRP) and economic residential polarization (ERP), on birth weight outcomes, which are established predictors of the newborn's future morbidity and mortality risk. Higher RRP and ERP was each associated with higher continuous birth weight and lower odds for low birth weight and small for gestational age, with evidence for effect modification by maternal race. On average, per interquartile range increase in RRP, the birth weight was 10.0 g (95% confidence interval: 8.0, 12.0) higher among babies born to white mothers versus 6.9 g (95% CI: 4.8, 9.0) higher among those born to black mothers. For ERP, it was 18.6 g (95% CI: 15.7, 21.5) higher among those that were born to white mothers versus 1.8 g (95% CI: -4.2, 7.8) higher among those born to black mothers. Racial and economic polarization towards more privileged groups was associated with healthier birth weight outcomes, with greater estimated effects in babies that were born to white mothers than those born to black mothers.

Sex-specific associations of maternal birthweight with offspring birthweight in the Omega study

PURPOSE

We investigated nonlinear and offspring sex-specific associations of maternal birthweight (BW) with offspring BW among participants of the Omega study, a pregnancy cohort.

METHODS

Maternal BW was modeled as a continuous variable, linear spline and binary variable indicating low birthweight (LBW; <2500 vs. ≥2500 grams). Offspring BW was modeled as a continuous and binary variable in regression models. Nonlinearity was assessed using likelihood ratio tests (LRTs) in marginal linear spline models.

RESULTS

For every 100-gram increase of maternal BW, offspring BW increased by 22.29 (95% CI: 17.57, 27.02) or 23.41 (95% CI: 6.87, 39.96) grams among mothers with normal BW or born macrosomic, respectively, but not among LBW mothers (β = -8.61 grams; 95% CI: -22.88, 5.65; LRT P-value = .0005). For every 100-gram increase in maternal BW, BW of male offspring increased 23.47 (95% CI: 16.75, 30.19) or 25.21 (95% CI: 4.35, 46.07) grams among mothers with normal BW or born macrosomic, respectively, whereas it decreased 31.39 grams (95% CI: -51.63, -11.15) among LBW mothers (LRT P-value < .0001). Corresponding increases in BW of female offspring (16-22 grams) did not differ among mothers with LBW, normal BW or macrosomia (LRT P-value = .9163).

CONCLUSIONS

Maternal and offspring BW associations are evident among normal BW and macrosomic mothers. These associations differ by offspring sex.

Mediation analysis of gestational age, congenital heart defects, and infant birth-weight

BACKGROUND

In this study we assessed the mediation role of the gestational age on the effect of the infant's congenital heart defects (CHD) on birth-weight.

METHODS

We used secondary data from the Baltimore-Washington Infant Study (1981-1989). Mediation analysis was employed to investigate whether gestational age acted as a mediator of the association between CHD and reduced birth-weight. We estimated the mediated effect, the mediation proportion, and their corresponding 95% confidence intervals (CI) using several methods.

RESULTS

There were 3362 CHD cases and 3564 controls in the dataset with mean birth-weight of 3071 (SD = 729) and 3353 (SD = 603) grams, respectively; the mean gestational age was 38.9 (SD = 2.7) and 39.6 (SD = 2.2) weeks, respectively. After adjusting for covariates, the estimated mediated effect by gestational age was 113.5 grams (95% CI, 92.4-134.2) and the mediation proportion was 40.7% (95% CI, 34.7%-46.6%), using the bootstrap approach.

CONCLUSIONS

Gestational age may account for about 41% of the overall effect of heart defects on reduced infant birth-weight. Improved prenatal care and other public health efforts that promote full term delivery, particularly targeting high-risk families and mothers known to be carrying a fetus with CHD, may therefore be expected to improve the birth-weight of these infants and their long term health.

Fetal size in a rural melanesian population with minimal risk factors for growth restriction: an observational ultrasound study from Papua New Guinea

We conducted a prospective longitudinal study of fetal size in rural Papua New Guinea (PNG) involving 439 ultrasound-dated singleton pregnancies with no obvious risk factors for growth restriction. Sonographically estimated fetal weights (EFWs; N = 788) and birth weights (N = 376) were included in a second-order polynomial regression model (optimal fit) to generate fetal weight centiles. Means for specific fetal biometric measurements were also estimated. Fetal weight centiles from a healthy PNG cohort were consistently lower than those derived from Caucasian and Congolese populations, which overestimated the proportion of fetuses measuring small for gestational age (SGA; < 10th centile). Tanzanian and global reference centiles (Caucasian weight reference adapted to our PNG cohort) were more similar to those observed in our cohort, but the global reference underestimated SGA. Individual biometric measurements did not differ significantly from other cohorts. In rural PNG, a locally derived nomogram may be most appropriate for detection of SGA fetuses.

Reproducing inequalities: luck, wallets, and the enduring effects of childhood health

In this article, I argue that research on social stratification, on intergenerational transmission of inequalities, and on the theory of factor payments and wage determination will be strengthened by studying the role played by early childhood health. I show that the inclusion of such a factor requires researchers to integrate theories in each of these fields with new theories linking early childhood health conditions and events that occur at later stages in the life course of individuals, particularly physical and mental health as well as disability and mortality. The empirical evidence I gather shows that early childhood health matters for the achievement of or social accession to, adult social class positions. Even if the magnitude of associations is not overwhelming, it is not weaker than that found between adult social accession and other, more conventional and better-studied individual characteristics, such as educational attainment. It is very likely that the evidence presented in this article grossly underplays the importance of early childhood health for adult socioeconomic achievement.

Reconsidering risk: adapting public policies to intergenerational determinants and biosocial interactions in health-related needs

According to recent research, interactions between infant health and environment can play crucial roles in clustering health and economic disadvantage among certain families. Researchers have provided a clear example of such intergenerational biosocial cycles when they document that interactions between parental low birth weight status and prenatal environment are associated with the risk of a low birth weight, and that interactions between a child's birth weight status and early childhood environment are associated with adult socioeconomic outcomes. In this article, we consider how existing policies may be revised to more effectively address such interactions between social and biological risk categories. We are particularly concerned in this discussion with revising risk categories so they can encompass biological risk, social risk, and developmental frameworks. A framework of biosocial risk is quite flexible and may be applied to a variety of issues and programs; however, in this article we focus on the single case of low birth weight to illustrate our argument. In considering specific applications, we further explore how attention to biosocial interactions may reshape Medicaid, special education, the Earned Income Tax Credit, and Temporary Assistance for Needy Families.