Maternal Work and Birth Outcome Disparities
Maternal Work and Birth Outcome Disparities
Objectives: We tested relations between aspects of maternal work and birth outcomes in a national sample and in subgroups known to experience disparities.
Methods: Three indices of work attributes (Status and Recognition, Physical Demands, and Exposure to Conflict) were derived by factor analysis of variables extracted from the Department of Labor's O*Net database. The indices were linked the National Longitudinal Survey of Youth using occupation codes for the primary jobs held by women who gave birth between 1979 and 2000 and worked during the quarter prior to birth (n = 3,386 births to n = 2,508 mothers). Multiple regression was used to model birth outcomes as functions of the work attribute indices, controlling for several measures of socioeconomic status and risk factors for adverse birth outcomes.
Results: In the full sample, work-related Physical Demands were associated with lower average birthweight and increased odds of preterm birth while Status and Recognition was associated with higher average birthweight and lower odds of fetal growth restriction. In stratified models, Status and Recognition was associated with higher birth weight among women with low (versus high) income and with lower odds of preterm birth among women with low (versus high) education. Physical Demands were associated with higher rates of preterm birth among women with low (versus high) income and education and among African-American mothers (compared to Whites).
Conclusions: The work environment is an important predictor of healthy births. Relations between maternal work attributes and birth outcomes differ by race/ethnicity and socioeconomic status and according to the outcome under investigation. Further research with measures of work attributes specific to maternal work experiences is recommended to confirm our findings.
The causes of persistent disparities in birth outcomes by maternal socioeconomic status and race/ethnicity remain unsolved mysteries in epidemiologic research. Like other population health indicators, birth outcomes are patterned along socioeconomicgradients with apparent improvements as income and education increase. Birth outcomes also vary by maternal race/ethnicity. For example, African-American infants are more likely than White infants to experience adverse outcomes and the greatest disparities are among infants born to mothers with high socioeconomic status. Paradoxically, despite a higher likelihood of socioeconomic disadvantage some Hispanic infants have outcomes that approximate those of White infants. For decades, such disparities have been evident in rates of low birthweight, prematurity, and fetal growth restriction—outcomes that together account for more than half of the mortality in the first year of life.
Maternal psychosocial stress has been advanced as one explanation for birth outcome disparities. Yet specific sources of differential exposure to stress remain elusive. With almost 70% of U.S. women working outside the home during at least part of pregnancy, work attributes and the work context warrant examination for their influence on birth outcomes. To the extent groups at high (or low) risk for poor birth outcomes disproportionately experience harmful (or protective) work exposures, greater disparities will arise.
Prior research indicates birth outcomes vary by job title and occupational class, as well as by specific work attributes. While moderate physical activity may be protective or not harmful for pregnant women, some studies report increased risk of poor outcomes with prolonged periods of standing, heavy lifting, assembly-line work, long work hours, job fatigue, low control over work pacing, and general measures of occupational stress.
Against findings of deleterious effects, some researchers report no associations between work attributes and birth outcomes. Comparison of results across studies is complicated by differences in occupational exposures and measurement within and between occupations. Many studies finding no effect were conducted outside the U.S., for example, in Canada, Europe, and Scandinavia where employee benefits, protections and exposures differ.
Socioeconomic status is one of the most influential confounding variables in work-birth outcome relationships. While studies have shown no associations between work stress and poor birth outcomes in samples of women with high or low socioeconomic status, few studies have samples with sufficient heterogeneity, size, or power to stratify by socioeconomic status or other factors associated with disparities.
Most work-birth outcome studies have focused on prematurity or low birthweight; few have considered influences on fetal growth restriction. Yet evidence suggests preterm birth and fetal growth are distinct outcomes although their precise etiologic pathways are not well understood. Without a better understanding of the mechanisms leading to each specific outcome, successful strategies for eliminating disparities are unlikely to be identified.
In the current study, we test associations between work attributes and birthweight, preterm birth, and fetal growth restriction.We assess the extent to which birth outcome disparities by race/ethnicity and socioeconomic status are explained by exposure to work attributes that plausibly influence birth outcomes and whether the influence of specific work attributes on birth outcomes differs in subgroups known to experience disparities.
Objectives: We tested relations between aspects of maternal work and birth outcomes in a national sample and in subgroups known to experience disparities.
Methods: Three indices of work attributes (Status and Recognition, Physical Demands, and Exposure to Conflict) were derived by factor analysis of variables extracted from the Department of Labor's O*Net database. The indices were linked the National Longitudinal Survey of Youth using occupation codes for the primary jobs held by women who gave birth between 1979 and 2000 and worked during the quarter prior to birth (n = 3,386 births to n = 2,508 mothers). Multiple regression was used to model birth outcomes as functions of the work attribute indices, controlling for several measures of socioeconomic status and risk factors for adverse birth outcomes.
Results: In the full sample, work-related Physical Demands were associated with lower average birthweight and increased odds of preterm birth while Status and Recognition was associated with higher average birthweight and lower odds of fetal growth restriction. In stratified models, Status and Recognition was associated with higher birth weight among women with low (versus high) income and with lower odds of preterm birth among women with low (versus high) education. Physical Demands were associated with higher rates of preterm birth among women with low (versus high) income and education and among African-American mothers (compared to Whites).
Conclusions: The work environment is an important predictor of healthy births. Relations between maternal work attributes and birth outcomes differ by race/ethnicity and socioeconomic status and according to the outcome under investigation. Further research with measures of work attributes specific to maternal work experiences is recommended to confirm our findings.
The causes of persistent disparities in birth outcomes by maternal socioeconomic status and race/ethnicity remain unsolved mysteries in epidemiologic research. Like other population health indicators, birth outcomes are patterned along socioeconomicgradients with apparent improvements as income and education increase. Birth outcomes also vary by maternal race/ethnicity. For example, African-American infants are more likely than White infants to experience adverse outcomes and the greatest disparities are among infants born to mothers with high socioeconomic status. Paradoxically, despite a higher likelihood of socioeconomic disadvantage some Hispanic infants have outcomes that approximate those of White infants. For decades, such disparities have been evident in rates of low birthweight, prematurity, and fetal growth restriction—outcomes that together account for more than half of the mortality in the first year of life.
Maternal psychosocial stress has been advanced as one explanation for birth outcome disparities. Yet specific sources of differential exposure to stress remain elusive. With almost 70% of U.S. women working outside the home during at least part of pregnancy, work attributes and the work context warrant examination for their influence on birth outcomes. To the extent groups at high (or low) risk for poor birth outcomes disproportionately experience harmful (or protective) work exposures, greater disparities will arise.
Prior research indicates birth outcomes vary by job title and occupational class, as well as by specific work attributes. While moderate physical activity may be protective or not harmful for pregnant women, some studies report increased risk of poor outcomes with prolonged periods of standing, heavy lifting, assembly-line work, long work hours, job fatigue, low control over work pacing, and general measures of occupational stress.
Against findings of deleterious effects, some researchers report no associations between work attributes and birth outcomes. Comparison of results across studies is complicated by differences in occupational exposures and measurement within and between occupations. Many studies finding no effect were conducted outside the U.S., for example, in Canada, Europe, and Scandinavia where employee benefits, protections and exposures differ.
Socioeconomic status is one of the most influential confounding variables in work-birth outcome relationships. While studies have shown no associations between work stress and poor birth outcomes in samples of women with high or low socioeconomic status, few studies have samples with sufficient heterogeneity, size, or power to stratify by socioeconomic status or other factors associated with disparities.
Most work-birth outcome studies have focused on prematurity or low birthweight; few have considered influences on fetal growth restriction. Yet evidence suggests preterm birth and fetal growth are distinct outcomes although their precise etiologic pathways are not well understood. Without a better understanding of the mechanisms leading to each specific outcome, successful strategies for eliminating disparities are unlikely to be identified.
In the current study, we test associations between work attributes and birthweight, preterm birth, and fetal growth restriction.We assess the extent to which birth outcome disparities by race/ethnicity and socioeconomic status are explained by exposure to work attributes that plausibly influence birth outcomes and whether the influence of specific work attributes on birth outcomes differs in subgroups known to experience disparities.
