The contribution of maternal working conditions to socio-economic inequalities in birth outcome

Impact of sex, race, and social determinants of health on neonatal outcomes

Despite the global improvements in neonatal outcomes, mortality and morbidity rates among preterm infants are still unacceptably high. Therefore, it is crucial to thoroughly analyze the factors that affect these outcomes, including sex, race, and social determinants of health. By comprehending the influence of these factors, we can work towards reducing their impact and enhancing the quality of neonatal care. This review will summarize the available evidence on sex differences, racial differences, and social determinants of health related to neonates. This review will discuss sex differences in neonatal outcomes in part I and racial differences with social determinants of health in part II. Research has shown that sex differences begin to manifest in the early part of the pregnancy. Hence, we will explore this topic under two main categories: (1) Antenatal and (2) Postnatal sex differences. We will also discuss long-term outcome differences wherever the evidence is available. Multiple factors determine health outcomes during pregnancy and the newborn period. Apart from the genetic, biological, and sex-based differences that influence fetal and neonatal outcomes, racial and social factors influence the health and well-being of developing humans. Race categorizes humans based on shared physical or social qualities into groups generally considered distinct within a given society. Social determinants of health (SDOH) are the non-medical factors that influence health outcomes. These factors can include a person's living conditions, access to healthy food, education, employment status, income level, and social support. Understanding these factors is essential in developing strategies to improve overall health outcomes in communities.

Maternal Occupational Risk Factors and Preterm Birth: A Systematic Review and Meta-Analysis

Objective: This systematic review and meta-analysis aimed to summarize the evidence on the relationship between physical occupational risks (high physical workload, long working hours, shift work, whole-body vibrations, prolonged standing, and heavy lifting) and preterm birth. Methods: A systematic review and meta-analysis was conducted across six databases to investigate the relationship between physical occupational risks and preterm birth. Result: A comprehensive analysis of 37 studies with varying sample sizes found moderate evidence of positive associations between high physical workload, long working hours, shift work, whole-body vibration, and preterm birth. Meta-analysis showed a 44% higher risk (OR 1.44, 95% CI 1.25-1.66) for preterm birth with long working hours and a 63% higher risk (OR 1.63, 95% CI 1.03-2.58) with shift work. Conclusion: Pregnant women in physically demanding jobs, those working long hours or on shifts, and those exposed to whole-body vibration have an increased risk of preterm birth. Employers should establish supportive workplaces, policymakers implement protective measures, healthcare providers conduct screenings, and pregnant women must stay informed and mitigate these job-related risks. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], Identifier [CRD42022357045].

Mediators of socioeconomic inequalities in preterm birth: a systematic review

BACKGROUND

Rates of preterm birth are substantial with significant inequalities. Understanding the role of risk factors on the pathway from maternal socioeconomic status (SES) to preterm birth can help inform interventions and policy. This study therefore aimed to identify mediators of the relationship between maternal SES and preterm birth, assess the strength of evidence, and evaluate the quality of methods used to assess mediation.

METHODS

Using Scopus, Medline OVID, "Medline In Process & Other Non-Indexed Citation", PsycINFO, and Social Science Citation Index (via Web of Science), search terms combined variations on mediation, socioeconomic status, and preterm birth. Citation and advanced Google searches supplemented this. Inclusion criteria guided screening and selection of observational studies Jan-2000 to July-2020. The metric extracted was the proportion of socioeconomic inequality in preterm birth explained by each mediator (e.g. 'proportion eliminated'). Included studies were narratively synthesised.

RESULTS

Of 22 studies included, over one-half used cohort design. Most studies had potential measurement bias for mediators, and only two studies fully adjusted for key confounders. Eighteen studies found significant socioeconomic inequalities in preterm birth. Studies assessed six groups of potential mediators: maternal smoking; maternal mental health; maternal physical health (including body mass index (BMI)); maternal lifestyle (including alcohol consumption); healthcare; and working and environmental conditions. There was high confidence of smoking during pregnancy (most frequently examined mediator) and maternal physical health mediating inequalities in preterm birth. Significant residual inequalities frequently remained. Difference-of-coefficients between models was the most common mediation analysis approach, only six studies assessed exposure-mediator interaction, and only two considered causal assumptions.

CONCLUSIONS

The substantial socioeconomic inequalities in preterm birth are only partly explained by six groups of mediators that have been studied, particularly maternal smoking in pregnancy. There is, however, a large residual direct effect of SES evident in most studies. Despite the mediation analysis approaches used limiting our ability to make causal inference, these findings highlight potential ways of intervening to reduce such inequalities. A focus on modifiable socioeconomic determinants, such as reducing poverty and educational inequality, is probably necessary to address inequalities in preterm birth, alongside action on mediating pathways.

A Critical Review on the Complex Interplay between Social Determinants of Health and Maternal and Infant Mortality

Background: U.S. maternal and infant mortality rates constitute an important public health problem, because these rates surpass those in developed countries and are characterized by stark disparities for racial/ethnic minorities, rural residents, and individuals with less privileged socioeconomic status due to social determinants of health (SDoH). Methods: A critical review of the maternal and infant mortality literature was performed to determine multilevel SDoH factors leading to mortality disparities with a life course lens. Results: Black mothers and infants fared the worst in terms of mortality rates, likely due to the accumulation of SDoH experienced as a result of structural racism across the life course. Upstream SDoH are important contributors to disparities in maternal and infant mortality. More research is needed on the effectiveness of continuous quality improvement initiatives for the maternal–infant dyad, and expanding programs such as paid maternity leave, quality, stable and affordable housing, and social safety-nets (Medicaid, CHIP, WIC), in reducing maternal and infant mortality. Finally, it is important to address research gaps in individual, interpersonal, community, and societal factors, because they affect maternal and infant mortality and related disparities. Conclusion: Key SDoH at multiple levels affect maternal and infant health. These SDoH shape and perpetuate disparities across the lifespan and are implicated in maternal and infant mortality disparities.

The impact of occupational activities during pregnancy on pregnancy outcomes: a systematic review and metaanalysis

OBJECTIVE

Data: An increasing number of studies suggest that exposure to physically demanding work during pregnancy could be associated with increased risks of adverse pregnancy outcomes, but the results remain conflicted and inconclusive. The purpose of this study was to examine the influence of occupational activities during pregnancy on maternal and fetal health outcomes.

STUDY

Studies of all designs (except case studies and reviews) that contained information on the relevant population (women who engaged in paid work during pregnancy), occupational exposures (heavy lifting, prolonged standing, prolonged walking, prolonged bending, and heavy physical workload), comparator (no exposure to the listed physical work demands), and outcomes (preterm birth, low birthweight, small for gestational age, miscarriage, gestational hypertension, preeclampsia, gestational diabetes mellitus, stillbirth, and intrauterine growth restriction) were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

Five electronic databases and 3 gray literature sources were searched up to March 15, 2019.

RESULTS

Eighty observational studies (N=853,149) were included. Low-to-very low certainty evidence revealed that lifting objects ≥11 kg was associated with an increased odds ratio of miscarriage (odds ratio, 1.31; 95% confidence interval, 1.08-1.58; I²=79%), and preeclampsia (odds ratio, 1.35; 95% confidence interval, 1.07-1.71; I²=0%). Lifting objects for a combined weight of ≥100 kg per day was associated with an increased odds of preterm delivery (odds ratio, 1.31; 95% confidence interval, 1.11-1.56; I²=0%) and having a low birthweight neonate (odds ratio, 2.08; 95% confidence interval, 1.06-4.11; I²=73%). Prolonged standing was associated with increased odds of preterm delivery (odds ratio, 1.11; 95% confidence interval, 1.02-1.22; I²=30%) and having a small-for-gestational-age neonate (odds ratio, 1.17; 95% confidence interval, 1.01-1.35; I²=41%). A heavy physical workload was associated with increased odds of preterm delivery (odds ratio, 1.23; 95% confidence interval, 1.07-1.41; I²=32%) and having a low birthweight neonate (odds ratio, 1.79; 95% confidence interval, 1.11-2.87; I²=87%). All other associations were not statistically significant. Dose-response analysis showed women stand for >2.5 hours per day (vs no standing) had a 10% increase in the odds of having a preterm delivery.

CONCLUSION

Physically demanding work during pregnancy is associated with an increased risk of adverse pregnancy outcomes.

Educational disparities in perinatal health in Denmark in the first decade of the 21st century: a register-based cohort study

OBJECTIVE

To investigate socioeconomic differences in six perinatal health outcomes in Denmark in the first decade of the 21st century.

DESIGN

A population-based cohort study.

SETTING

Danish national registries.

PARTICIPANTS

A total of 646 829 live born children and 3076 stillborn children (≥22+0 weeks of gestation) born in Denmark from 2000 to 2009. We excluded children with implausible relations between birth weight and gestational age (n=644), children without information on maternal country of origin (n=138) and implausible values of maternal year of birth (n=36).

MAIN OUTCOME MEASURES

We investigated the following perinatal health outcomes: stillbirth, neonatal and postneonatal mortality, small-for-gestational age, preterm birth grated into moderate preterm, very preterm and extremely preterm, and congenital anomalies registered in the first year of life.

RESULTS

Maternal educational level was inversely associated with all adverse perinatal outcomes. For all examined outcomes, the risk association displayed a clear gradient across the educational levels. The associations remained after adjustment for maternal age, maternal country of origin and maternal year of birth. Compared with mothers with vocational education, mothers with more than 15 years of education had an adjusted risk ratio for stillbirth of 0.64(95% CI 0.56 to 0.72). The corresponding adjusted risk ratios for neonatal mortality, postneonatal mortality, congenital anomalies, moderate preterm birth and small-for-gestational age were, respectively, 0.79(95% CI 0.67 to 0.93), 0.57(95% CI 0.42 to 0.78), 0.87(95% CI 0.83 to 0.91), 0.80(95% CI 0.77 to 0.83) and 0.83(95% CI 0.81 to 0.85).

CONCLUSION

Substantial educational inequalities in perinatal health were still present in Denmark in the first decade of the 21st century.

Deprivation, occupational hazards and perinatal outcomes in pregnant workers

BACKGROUND

Recent global economic difficulties have widened social inequalities, but their impact on pregnant workers is not known.

AIMS

To investigate the association between deprivation, exposure to occupational hazards and adverse perinatal outcomes in pregnant workers.

METHODS

A cross-sectional study performed in 2014 in French occupational health services. Eligible workers were women who had worked during their pregnancy and had a medical visit by occupational health physicians (OHPs) after delivery and at the time of returning to work. Deprivation was measured using the EPICES scale (Evaluation of Precariousness and Inequalities in Health Examination Centres). Information on birth outcomes was self-reported. Occupational risks for pregnancy were assessed by OHPs. Jobs were coded by the occupational health team using standardized French nomenclature. The groups (deprivation/no deprivation) were compared using univariate (chi-squared test) and multivariate Poisson regression analyses.

RESULTS

Of 1402 pregnant workers, 293 (21%) were classed as deprived. This group more frequently encountered occupational hazards, particularly for physical exposures (P < 0.001), and had a higher risk of cumulated occupational hazards of three or more for pregnancy [adjusted relative risk (RRa) = 4.2; 95% confidence interval (CI) 2.2-7.9]. Our findings suggest that deprivation and exposure to three or more occupational hazards during pregnancy cumulatively increased the risk of pre-term birth (RRa = 3.9; 95% CI 1.2-12.4).

CONCLUSIONS

Our data suggest that deprived pregnant workers are an occupationally vulnerable group.

All part of the job? The contribution of the psychosocial and physical work environment to health inequalities in Europe and the European health divide

This study is the first to examine the contribution of both psychosocial and physical risk factors to occupational inequalities in self-assessed health in Europe. Data from 27 countries were obtained from the 2010 European Working Conditions Survey for men and women aged 16 to 60 (n = 21,803). Multilevel logistic regression analyses (random intercept) were applied, estimating odds ratios of reporting less than good health. Analyses indicate that physical working conditions account for a substantial proportion of occupational inequalities in health in both Central/Eastern and Western Europe. Physical, rather than psychosocial, working conditions seem to have the largest effect on self-assessed health in manual classes. For example, controlling for physical working conditions reduced the inequalities in the prevalence of"less than good health" between the lowest (semi- and unskilled manual workers) and highest (higher controllers) occupational groups in Europe by almost 50 percent (Odds Ratio 1.87, 95% Confidence Interval 1.62-2.16 to 1.42, 1.23-1.65). Physical working conditions contribute substantially to health inequalities across "post-industrial" Europe, with women in manual occupations being particularly vulnerable, especially those living in Central/Eastern Europe. An increased political and academic focus on physical working conditions is needed to explain and potentially reduce occupational inequalities in health.

Work organization, job insecurity, and occupational health disparities

BACKGROUND

Changes in employment conditions in the global economy over the past 30 years have led to increased job insecurity and other work organization hazards. These hazards may play a role in creating and sustaining occupational health disparities by socioeconomic position, gender, race, ethnicity, and immigration status.

METHODS

A conceptual model was developed to guide the review of 103 relevant articles or chapters on the role of work organization and occupational health disparities identified through a comprehensive search conducted by NIOSH. A second review was conducted of employment and workplace policies and programs designed to reduce the health and safety risks due to job insecurity and other work organization hazards.

RESULTS

There is consistent evidence that workers in lower socioeconomic or social class positions are exposed to greater job insecurity and other work organization hazards than workers in higher socioeconomic positions. Likewise, racial and ethnic minorities and immigrants are exposed to greater job insecurity. Limited research examining the effects of interventions targeting work organization hazards on disparities has been conducted; nonetheless, intervention strategies are available and evidence suggests they are effective.

CONCLUSIONS

Job insecurity and work organization hazards play a role in creating and sustaining occupational health disparities. Employment and workplace policies and programs have the potential to reduce these hazards, and to reduce disparities.

Work activities and risk of prematurity, low birth weight and pre-eclampsia: an updated review with meta-analysis

OBJECTIVES

We assessed the evidence relating preterm delivery (PTD), low birth weight, small for gestational age (SGA), pre-eclampsia and gestational hypertension to five occupational exposures (working hours, shift work, lifting, standing and physical workload). We conducted a systematic search in Medline and Embase (1966 to 2011), updating a previous search with a further 6 years of observations.

METHODS

As before, combinations of keywords and medical subject headings were used. Each relevant paper was assessed for completeness of reporting and potential for important bias or confounding, and its effect estimates abstracted. Where similar definitions of exposure and outcome existed we calculated pooled estimates of relative risk (RR) in meta-analysis.

RESULTS

Analysis was based on 86 reports (32 cohort investigations, 57 with usable data on PTD, 54 on birth weight and 11 on pre-eclampsia/gestational hypertension); 33 reports were new to this review. For PTD, findings across a substantial evidence base were generally consistent, effectively ruling out large effects (eg, RR>1.2). Larger and higher quality studies were less positive, while meta-estimates of risk were smaller than in previous analyses and best estimates pointed to modest or null effects (RR 1.04 to 1.18). For SGA, the position was similar but meta-estimates were even closer to the null (eight of nine RRs ≤ 1.07). For pre-eclampsia/gestational hypertension the evidence base remains insufficient.

CONCLUSIONS

The balance of evidence is against large effects for the associations investigated. As the evidence base has grown, estimates of risk in relation to these outcomes have become smaller.

Grossesse et travail : au-delà des facteurs de risques pour la santé

Cet article met en lumière les risques pour la santé liés au travail des femmes en abordant la problématique de la conciliation travail-grossesse. Cette analyse adopte comme cadre de référence la division sexuelle du travail (Kergoat, 2004). Cette perspective analytique est rarement intégrée dans les études portant sur la santé des femmes au travail. Le contexte de pénurie de main d'oeuvre qui touche actuellement le Québec en raison du vieillissement de sa population active, et dans certains secteurs en raison de la pénibilité des conditions de travail, marque l'importance d'ajouter cette perspective dans l'analyse de la santé des femmes au travail. Pour les femmes, l'expérience vécue du travail durant la grossesse constitue l'élément annonciateur du degré d'acceptation de la part des milieux de travail et de la société québécoise des spécificités féminines au travail. L'article fait ressortir où en sont rendues les organisations sur ce plan, à travers l'étude du traitement des demandes de retrait préventif de la travailleuse enceinte, droit inclus au Québec dans la Loi sur la santé et sécurité au travail. Malgré des avancées significatives dans certains milieux, on constate encore la prédominance d'une logique gestionnaire traditionnelle et sexiste dans l'application du droit qui mène les travailleuses au retrait du travail durant leur grossesse. La recherche a été menée auprès d'employeurs, de représentants syndicaux et de travailleuses du secteur hospitalier.

Psychosocial work stress during pregnancy and birthweight

Although there is a growing interest in the health effects of psychosocial work stress, studies on the relationships between job stress and adverse reproductive outcome are limited. We, therefore, investigated the associations between prenatal maternal occupational stress and birthweight using 310 mother-infant pairs included in the Mothers and Children's Environmental Health (MOCEH) study. Information on job stress was collected by interviewing women at enrollment during the first trimester of pregnancy using standardised questionnaires, namely, the Job Content Questionnaire (JCQ) of job strain and effort-reward imbalance (ERI) questionnaires. Regression analyses were carried out. Decision latitude scores of the JCQ were found to be positively related to birthweight, while ERI ratios determined using the ERI model were found to be inversely related to gestational age. In addition, a passive job as defined by the job strain model was found to be associated with a lower birthweight, compared with a relaxed job. These results suggest that work-related psychosocial stress in pregnant women appears to affect birth outcomes, such as birthweight and gestational age.

Immigrants' duration of residence and adverse birth outcomes: a population-based study

OBJECTIVE

This study aimed to examine preterm and small-for-gestational-age (SGA) births among immigrants, by duration of residence, and to compare them with the Canadian-born population.

DESIGN

Population-based cross-sectional study with retrospective assessment of immigration.

SETTING

Metropolitan areas of Ontario, Canada.

POPULATION

A total of 83 233 singleton newborns born to immigrant mothers and 314 237 newborns born to non-immigrant mothers.

METHODS

We linked a database of immigrants acquiring permanent residence in Ontario, Canada, in the period 1985-2000 with mother-infant hospital records (2002-2007). Duration of residence was measured as completed years from arrival to Canada to delivery/birth. Logistic regression models were used to estimate the effects of duration of residence with adjusted odds ratios and 95% confidence intervals. In analyses restricted to immigrants only, hierarchical models were used to account for the clustering of births into maternal countries of birth.

MAIN OUTCOME MEASURES

Preterm birth (PTB) and SGA birth.

RESULTS

Recent immigrants (<5 years) had a lower risk of PTB (4.7%) than non-immigrants (6.2%), but those with > or =15 years of stay were at higher risk (7.4%). Among immigrants, a 5-year increase in Canadian residence was associated with an increase in PTB (AOR 1.14, 95% CI 1.10-1.19), but not in SGA birth (AOR 0.99, 95% CI 0.96-1.02).

CONCLUSIONS

Time since migration was associated with increases in the risk of PTB, but was not associated with an increase in SGA births. Ignoring duration of residence may mask important disparities in preterm delivery between immigrants and non-immigrants, and between immigrant subgroups categorised by their duration of residence.

Maternal catecholamine levels in midpregnancy and risk of preterm delivery

Associations between stress hormones and preterm delivery have not been fully explored. In this study, pregnant women enrolled from 52 clinics in 5 Michigan communities (1998-2004) provided urine samples for 3 days (waking and bedtime) during midpregnancy. Urinary catecholamine levels (epinephrine, norepinephrine, and dopamine) were measured in a subcohort (247 preterm and 760 term deliveries), and a 3-day median value was calculated. Polytomous logistic regression models assessed relations between catecholamine quartiles (of the median) and a 4-level outcome variable (i.e., term (referent) and 3 preterm delivery subtypes: spontaneous; premature rupture of membranes; and medically indicated). Final models incorporated other relevant covariates (e.g., creatinine, demographic, behavior). The risk of spontaneous preterm delivery was increased in the highest versus lowest quartile of norepinephrine and dopamine: norepinephrine, waking (adjusted odds ratio (AOR) = 3.7, 95% confidence interval (CI): 1.8, 7.9) and bedtime (AOR = 2.5, 95% CI: 1.3, 4.9); dopamine, waking (AOR = 2.6, 95% CI: 1.4, 5.1) and bedtime (AOR = 2.3, 95% CI: 1.2, 4.6). Adjusted odds ratios were further strengthened after removing women whose placentas showed evidence of acute infection or vascular pathology. High catecholamine levels in maternal urine may be indicative of excess stressors and/or predisposition to elevated sympathetic activation that contributes to increased risk of spontaneous preterm delivery.

From paradox to disparity: trends in neonatal death in very low birth weight non-Hispanic black and white infants, 1989-2004

OBJECTIVES

To examine temporal trends in race-specific neonatal death in California to determine whether the overall decline in mortality attenuated the paradoxical survival advantage of very low birth weight (VLBW; birth weight < 1500 g) non-Hispanic black infants relative to VLBW non-Hispanic white infants.

STUDY DESIGN

The data set comprised the California birth cohort file on non-Hispanic black and non-Hispanic white VLBW neonatal mortality for 1989-2004. Logistic regression methods were used to control for potentially confounding maternal characteristics.

RESULTS

In 1989 and 1990, non-Hispanic black VLBW infants demonstrated a paradox of lower neonatal mortality (adjusted odds ratio [aOR] = 0.84; 95% confidence interval [CI] = 0.75-0.94). This survival advantage disappeared after 1991, however. In 2003 and 2004, the incidence of neonatal mortality increased in non-Hispanic black VLBW infants but decreased in non-Hispanic white VLBW infants, resulting in a racial disparity (aOR = 1.34; 95% CI = 1.14-1.56).

CONCLUSIONS

An initial survival paradox transformed into a disparity. The magnitude of this non-Hispanic black/non-Hispanic white VLBW disparity rose to its highest levels in the last 2 years of the study period. Moreover, the steady mortality increase in VLBW non-Hispanic black VLBW infants since 2001 reversed the secular decline in neonatal mortality in this population. Our findings underscore the need to augment strategies to improve the health trajectory of gestation in non-Hispanic black women.

Documenting and comparing plant species diversity by using numerical and parametric methods in Khaje Kalat, NE Iran

The aim was to examine and document several aspects of numerical diversity such as species richness, species diversity and evenness and to compare diversity in different slope aspects of the area by using numerical and parametric methods. About 193 quadrats of 4 m2 were located according to the nature of vegetation. Species composition and their abundance were recorded in a two-year period (2005 to 2006). The result of field investigation was collecting and identifying of the total 225 plant species belonging to 154 genera and 37 families. The abundance data were subjected to analyses by specific diversity packages to characterize and obtain numerical indices (Shannon, Simpson, Brillouin, McIntosh, etc.,) and parametric families of species diversity. Numerical indices were calculated and documented for monitoring purposes. The results of diversity in main slope aspects (N, S, E, W) showed higher species richness and species diversity indices in the north aspect than in the others but it was not true with evenness indices. About 30 species such as Acanthophyllum glandulosum, Acroptilon repens, Alcea tiliacea, Bromus sericeous, Astragalus turbinatus, Centaurea balsamita etc., were detected exclusively in the north aspect. This can be important in reducing the evenness. Diversity comparing by using rank-abundance plot as well as diversity ordering of Hill, Renyi and Patil and Taillie confirmed high species diversity in the north yet the result of ANOVA showed no significant differences in the four aspects. The result of diversity based on the models revealed that the whole area, the south and the west aspects follow lognormal distribution, north aspect follows logarithmic whereas the east follows both lognormal and logarithmic distribution. In other word, a shift from being lognormal to logarithmic model was observed in the east aspect.