Inequalities In Preterm Birth Research Articles

Inequalities in preterm birth by deprivation and ethnicity: A national cohort study in England

Abstract Background Preterm birth has decreased in the UK; however, the extent of inequalities remains unclear. This study aimed to quantify socioeconomic and ethnic inequalities in preterm birth rates using routinely collected maternity data in England. Methods Retrospective analysis of cohort data from the NHS England Hospital Episode Statistics (HES). All women aged 13-55 with a singleton livebirth (April 2018 to March 2021) at 24-42 weeks were included. Multivariate Poisson regression was used to estimate the rate of preterm birth (livebirth between 24 + 0 and 36 + 6 weeks’) for each ethnic and deprivation postcode group, these were compared to white women from the least deprived 20% of areas. We iteratively developed the model, adjusting for covariates associated with preterm birth. A post-hoc calculation identified the rate of preterm birth for each ethnic group at each level of deprivation. Results We identified 1,111,045 livebirths between April 2018 and March 2021. The rate of preterm birth increased with socioeconomic deprivation and was highest at 7.1% per 100 livebirths (95%CI:7.00-7.20) in women living in the 20% most deprived areas, compared to 5.6% (95%CI:5.50-5.74) in women in the 20% least deprived areas. White women had the lowest preterm birth rate at 6.5% (95%CI:6.47-6.58) and South Asian women had the highest rate at 6.9% (95%CI:6.76-7.04) (Table 2). The rate of preterm birth increased according to increased area-level deprivation across all ethnic groups. In areas of high deprivation, the preterm birth rate was similar across ethnic groups. Whereas in less deprived areas, there were marked inequalities between ethnic groups. Conclusions Inequalities in preterm birth remain, despite overall decreases in preterm birth. We found area deprivation and individual ethnicity interact to increase the risk of preterm birth in marginalized communities. Interventions need to holistically consider the structural and socioenvironmental determinants of preterm birth. Key messages • Area deprivation and ethnicity remain key drivers of inequalities in preterm birth, despite overall decreases in preterm birth. • To reduce inequalities tailored prevention strategies are needed to address socioenvironmental and structural determinants of preterm birth in high deprivation areas and minoritized ethnicity groups.

Socioeconomic and ethnic disparities in preterm births in an English maternity setting: a population-based study of 1.3 million births

BackgroundPreterm birth is a major cause of infant mortality and morbidity and accounts for 7–8% of births in the UK. It is more common in women from socially deprived areas and from minority ethnic groups, but the reasons for this disparity are poorly understood. To inform interventions to improve child survival and their quality of life, this study examined the socioeconomic and ethnic inequalities in preterm births (< 37 weeks of gestation at birth) within Health Trusts in England.MethodsThis study investigated socioeconomic and ethnic inequalities in preterm birth rates across the National Health Service (NHS) in England. The NHS in England can be split into different units known as Trusts. We visualised between-Trust differences in preterm birth rates. Health Trusts were classified into five groups based on their standard deviation (SD) variation from the average national preterm birth rate. We used modified Poisson regression to compute risk ratios (RR) and 95% confidence intervals (95% CI) with generalised estimating equations.ResultsThe preterm birth rate ranged from 6.8/100 births for women living in the least deprived areas to 8.8/100 births for those living in the most deprived areas. Similarly, the preterm birth rate ranged from 7.8/100 births for white women, up to 8.6/100 births for black women. Some Health Trusts had lower than average preterm birth rates in white women whilst concurrently having higher than average preterm birth rates in black and Asian women. The risk of preterm birth was higher for women living in the most deprived areas and ethnicity (Asian).ConclusionsThere was evidence of variation in rates of preterm birth by ethnic group, with some Trusts reporting below average rates in white ethnic groups whilst concurrently reporting well above average rates for women from Asian or black ethnic groups. The risk of preterm birth varied substantially at the intersectionality of maternal ethnicity and the level of socioeconomic deprivation of their residency. In the absence of other explanations, these findings suggest that even within the same Health Trust, maternity care may vary depending on the women’s ethnicity and/or whether she lives in an area of high socioeconomic deprivation. Thus, social factors are likely key determinants of inequality in preterm birth rather than provision of maternity care alone.

How are socioeconomic inequalities in preterm birth explained by maternal smoking and maternal body mass index: A mediation analysis.

Preterm birth affects between 7% and 8% of births in the UK and is a leading cause of infant mortality and childhood disability. Prevalence of preterm birth has been shown to have significant and consistent socioeconomic inequalities. To estimate how much of the association between socioeconomic status (SES) and gestational age at birth is mediated by maternal smoking status and maternal body mass index (BMI). Retrospective cohort study of a maternity hospital in the UK. The analysis included all singleton live births between April 2009 and March 2020 to mothers 18 years old and over, between 22 weeks and 43 weeks gestation. We estimate two measures of mediation for four low gestational age categories: (i) The proportion eliminated the percentage of the effect of SES on low gestational age at birth that would be eliminated by removing the mediators, through the Controlled Direct Effects estimated using serial log-binomial regressions; and (ii) The proportion mediated is the percentage of the effect removed by equalising the distribution of the mediators across socioeconomic groups, estimated using Interventional Disparity Measures calculated through Monte Carlo simulations. Overall, 81,219 births were included, with 63.7% low SES. The risk of extremely (0.3% of all births), very (0.7%) and moderately preterm birth (6.3%) was 1.71 (95% Confidence Interval [CI] 1.29, 2.31), 1.43 (95% CI 1.18, 1.73) and 1.26 (95% CI 1.19, 1.34) times higher in the low SES, compared to higher SES respectively. The proportion of this inequality eliminated by removing both maternal smoking and BMI was 43.4% for moderately preterm births. The proportion mediated for smoking was 33.9%, 43.0% and 48.4% respectively. Smoking during pregnancy is a key mediator of inequalities in preterm birth, representing an area for local action to reduce social inequalities in preterm birth.

Ethnic differences in preterm birth in Southwest China, 2014-2018: A population-based observational study.

ObjectivePreterm birth is a major healthcare problem and has been rising gradually in the past three decades in China. Yet the ethnic differences in the rates and distributions of preterm birth remain largely unknown in China. This study used data from Yunnan, a multiethnic province, to explore the differences in preterm birth across ethnicities.MethodsA population-based observational study was conducted based on data from the National Free Preconception Health Examination Project in rural Yunnan from Jan 1, 2014 to Dec 31, 2018. Pregnancies with at least one livebirth were included in this study. We estimated the rates and 95% confidence intervals (CIs) of overall preterm birth (born < 37 weeks’ gestation), moderate to late preterm birth (born between 32 and <37 weeks’ gestation), very preterm birth (born between 28 and 31 weeks’ gestation), and extremely preterm birth (born < 28 weeks’ gestation) across maternal ethnicity and compared them using log-binomial regressions. Multivariable log-binomial regressions were used to assess the association between maternal ethnicity and preterm birth with adjustment for potential confounders, including year of delivery, maternal age at delivery, education, occupation, pre-pregnancy body mass index, history of chronic disease, history of preterm birth, smoking and drinking alcohol during early pregnancy, and parity and multiple pregnancy of current pregnancy.ResultsAmong 195,325 women who delivered at least one live baby, 7.90% (95% CI, 7.78–8.02%) were born preterm. The rates of moderate to late preterm birth, very preterm birth, and extremely preterm birth were 6.20% (95% CI, 6.09–6.30%), 1.18% (95% CI, 1.13–1.23%), and 0.52% (95% CI, 0.49–0.56%), respectively. The rates of overall preterm birth, moderate to late preterm birth, very preterm birth, and extremely preterm birth differed across maternal ethnicity. The preterm birth rates in Dai (10.73%), Miao (13.23%), Lisu (12.64%), Zhuang (11.77%), Wa (10.52%), and Lagu (12.34%) women were significantly higher than that in Han women, and the adjusted relative risks were 1.45 [95% CI, 1.36, 1.54], 1.74 (95% CI, 1.62, 1.86), 1.60 (95% CI, 1.47, 1.75), 1.60 (95% CI, 1.46, 1.75), 1.40 (95% CI, 1.22, 1.60), and 1.67 (95% CI, 1.50, 1.87) respectively. There was no difference in preterm birth rate between Han women and Hani, Bai, or Hui women.ConclusionThis study found notable differences in the rates of preterm birth and its sub-categories across maternal ethnicities, which were especially higher in ethnic minority women. The findings suggest that greater efforts to reduce ethnic inequalities in preterm birth. Future studies are warranted to understand the drivers of ethnic inequalities in preterm birth in China.

Mediators of socioeconomic inequalities in preterm birth: a systematic review

BackgroundRates 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.MethodsUsing 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.ResultsOf 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.ConclusionsThe 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.

Ability of municipality-level deprivation indices to capture social inequalities in perinatal health in France: A nationwide study using preterm birth and small for gestational age to illustrate their relevance

BackgroundEvidence-based policy-making to reduce perinatal health inequalities requires an accurate measure of social disparities. We aimed to evaluate the relevance of two municipality-level deprivation indices (DIs), the French-Deprivation-Index (FDep) and the French-European-Deprivation-Index (FEDI) in perinatal health through two key perinatal outcomes: preterm birth (PTB) and small-for-gestational-age (SGA).MethodsWe used two data sources: The French National Perinatal Surveys (NPS) and the French national health data system (SNDS). Using the former, we compared the gradients of the associations between individual socioeconomic characteristics (educational level and income) and “PTB and SGA” and associations between municipality-level DIs (Q1:least deprived; Q5:most deprived) and “PTB and SGA”. Using the SNDS, we then studied the association between each component of the two DIs (census data, 2015) and “PTB and SGA”. Adjusted odds ratios (aOR) were estimated using multilevel logistic regression with random intercept at the municipality level.ResultsIn the NPS (N = 26,238), PTB and SGA were associated with two individual socioeconomic characteristics: maternal educational level (≤ lower secondary school vs. ≥ Bachelor’s degree or equivalent, PTB: aOR = 1.43 [1.22–1.68], SGA: (1.31 [1.61–1.49]) and household income (< 1000 € vs. ≥ 3000 €, PTB: 1.55 [1.25–1.92], SGA: 1.69 [1.45–1.98]). For both FDep and FEDI, PTB and SGA were more frequent in deprived municipalities (Q5: 7.8% vs. Q1: 6.3% and 9.0% vs. 5.9% for PTB, respectively, and 12.0% vs. 10.3% and 11.9% vs. 10.2% for SGA, respectively). However, after adjustment, neither FDep nor FEDI showed a significant gradient with PTB or SGA. In the SNDS (N = 726,497), no FDep component, and only three FEDI components were significantly associated (specifically, the % of the population with ≤ lower secondary level of education with both outcomes (PTB: 1.5 [1.15–1.96]); SGA: 1.25 [1.03–1.51]), the % of overcrowded (i.e., > 1 person per room) houses (1.63 [1.15–2.32]) with PTB only, and unskilled farm workers with SGA only (1.52 [1.29–1.79]).ConclusionSome components of FDep and FEDI were less relevant than others for capturing ecological inequalities in PTB and SGA. Results varied for each DI and perinatal outcome studied. These findings highlight the importance of testing DI relevance prior to examining perinatal health inequalities, and suggest the need to develop DIs that are suitable for pregnant women.

Different maternal age patterns of preterm birth: Interplay of race/ethnicity, chronic stress, and marital status.

The aim of this study was to examine whether the preterm birth (PTB) risks according to maternal age is altered by a woman's marital status and chronic stress among non-Hispanic (N-H) White, N-H Black, Hispanic, and Asian women. This researcher analyzed the Pregnancy Risk Assessment Monitoring System data for New York City and Washington State linked with the birth certificates for 2004-2007. The sample included 6344 singleton live births without birth defects to women aged 18 years or older identified as N-H White, N-H Black, Hispanic, or Asian. The outcome was PTB. Maternal age-specific PTB rates were calculated according to race/ethnicity, marital status, and chronic stress. Linear trends of PTB rates with maternal age were evaluated by the Mantel-Haenszel χ2 test. Marriage had a protective effect against PTB at advancing maternal age across racial/ethnic groups. The health benefit of marriage was strong, particularly among the married N-H Black and Asian women, manifested as a maternal age-related decrease in the PTB rate (reverse-weathering). In contrast, women not married showed a maternal age-related increase in the PTB rate (weathering) across the racial/ethnic groups. Under higher chronic stress, married women generally experienced less weathering about PTB. These patterns were observed with noticeable racial/ethnic variations. Acknowledging the different dynamics among maternal age, marital status, and chronic stress by race/ethnicity could help shed light on the psychosocial mechanisms underlying the racial/ethnic inequalities in PTB in the United States. To that end, future studies should use more nuanced measurements of paternal support and chronic stress.

The risk of preterm birth in combinations of socioeconomic position and mental health conditions in different age groups: a Danish nationwide register-based cohort study

BackgroundInequality in preterm birth is a world-wide challenge that has proved difficult for maternity care services to meet. Reducing the inequality requires identification of pregnant women at particularly high risk of preterm birth in order to target interventions. Therefore, the aim was to estimate the risk of preterm birth in women with different combinations of socioeconomic position, mental health conditions, and age.MethodsIn this nationwide register-based cohort study, we included all first-time mothers that gave birth to a singleton liveborn infant in Denmark between 2000 and 2016. The absolute and relative risk of preterm birth (< 37 weeks of gestation) was examined in different combinations of educational level (high, intermediate, and low) and mental health conditions (no, minor, and moderate/severe) in three age strata (≤23, 24–30, and ≥ 31 years). We estimated the relative risk using Poisson regression with a robust error variance. As additive interaction can help identify subgroups where limited resources can be of best use, we measured the attributable proportion to assess the risk that is due to interaction of the different exposures.ResultsOf the 415,523 included first-time mothers, 6.3% gave birth prematurely. The risk of preterm birth increased with decreasing educational level and increasing severity of mental health conditions in all age strata, but most in women aged ≥31 years. The highest absolute risk was 12.9% [95% CI: 11.2;14.8%] in women aged ≥31 years with low education and moderate/severe mental health conditions resulting in a relative risk of 2.23 [95% CI: 1.93–2.58] compared to the unexposed reference group in that age strata. We found positive additive interaction between low education and mental health conditions in women aged 24–30 and ≥ 31 years and between age ≥ 31 years and combinations of mental health conditions and educational levels.ConclusionThe inequality in preterm birth increased with increasing age. To reduce inequality in preterm birth focused attention on women with higher age further combined with lower educational levels and mental health conditions is essential.

The Decomposition of Socioeconomic Factors in Inequality in Preterm Birth; the Results of a Cohort Study Based on the Concentration Index Approach

Background: Preterm labor is a crucial factor in neonatal morbidity and mortality. The present study aims to investigate the effects of Socioeconomic Status (SES) on preterm birth and to decompose the main inequalities affecting preterm birth. Materials and Methods: In a cohort study in 2017, 458 pregnant women in Ilam, Iran, were followed from the 20th gestational week up to the labor. All participants were followed up according to the Prenatal Care Schedule approved by the Ministry of Health of the Islamic Republic of Iran from the beginning to the end of the study. The results of participants' laboratory tests were collected based on the records from their pregnancy documents. A code was inserted in the prenatal care booklet of each participant for exchanging information between the researcher and participants. The Concentration Index (CI) was used to determine inequality. The Inequality Index was decomposed to find out the main sources of inequality in preterm infants. Distributive Analysis Stata Package was used for estimating CI. Results: Of the total of 458 participants, 12% had preterm labor. The number of male newborns was 219 (47.8%). Also, the prevalence of preterm labor was more in mothers aged 20 to 31 years (p < 0.001), housewives (p=0.037), and women with lower socioeconomic status (p < 0.001). The socioeconomic contributors to inequality were the mother’s age (p=0.008), father’s age (p=0.005), father’s education (p=0.003), and father's job (p < 0.001). The main factors of inequality were mother’s age (8%), father’s age (3%), father’s education (5%), and father's job (25%). Conclusion: Overall, 12% of our study population had preterm labor. Preterm birth was significantly more observed among mothers of lower socioeconomic status. Some SES, including the mother's age, father’s age, father’s education, and father’s job, were important factors in preterm inequality among Iranian mothers.

The risk of preterm birth in combinations of mental disorder and socioeconomic position among Danish women

Abstract Background Inequality in preterm birth is a public health challenge requiring identification of pregnant women at particularly high risk of preterm birth. Therefore, the aim was to estimate the risk of preterm birth in women with different combinations of mental health conditions and socioeconomic position. Methods Based on Danish registries, we conducted a nationwide cohort study including all first-time mothers giving birth to a singleton liveborn infant in Denmark between 2000 through 2016. We examined the risk of preterm birth (&amp;lt;37 weeks of gestation) in different combinations of mental health conditions (no, minor, and moderate/severe) and educational level (high, intermediate, and low) in three age strata (&amp;lt;25, 25-30, and &amp;gt;30 years). The relative risk of preterm birth was estimated using Poisson regression with a robust error variance. We measured the attributable proportion to assess additive interaction between the effects of exposures. Results Of the 415,523 included first time mothers, 29,069 (7,0%) gave birth preterm. The risk of preterm birth increased in combinations of higher degree of mental health conditions, lower degree of educational level, and increasing age. Women aged&amp;gt;30 years with moderate/severe mental health conditions and low educational level had the highest risk of preterm birth (13.7%). The analysis of additive interaction revealed only a limited additional effect of being exposed to mental health conditions and lower educational levels in each age strata. However, positive additive interaction was found between age&amp;gt;30 year and combinations of mental health conditions and educational level. Conclusions Substantial inequality in preterm birth remains with increasing risk in women with combinations of higher degree of mental health conditions and lower degree of educational level. In the prevention of inequality in preterm birth special attention on women aged&amp;gt;30 years exposed to mental health conditions and lower educational levels is essential

Socioeconomic inequality in preterm birth in four Brazilian birth cohort studies

ObjectiveTo analyze economic inequality (absolute and relative) due to family income in relation to the occurrence of preterm births in Southern Brazil. MethodsFour birth cohort studies were conducted in the years 1982, 1993, 2004, and 2011. The main exposure was monthly family income and the primary outcome was preterm birth. The inequalities were calculated using the slope index of inequality and the relative index of inequality, adjusted for maternal skin color, education, age, and marital status. ResultsThe prevalence of preterm births increased from 5.8% to approximately 14% (p‐trend<0.001). Late preterm births comprised the highest proportion among the preterm births in all studies, although their rates decreased over the years. The analysis on the slope index of inequality demonstrated that income inequity arose in the 1993, 2004, and 2011 studies. After adjustment, only the 2004 study maintained the difference between the poorest and the richest subjects, which was 6.3 percentage points. The relative index of inequality showed that, in all studies, the poorest mothers were more likely to have preterm newborns than the richest. After adjustment for confounding factors, it was observed that the poorest mothers only had a greater chance of this outcome in 2004. ConclusionIn a final model, economic inequities resulting from income were found in relation to preterm births only in 2004, although a higher prevalence of prematurity continued to be observed in the poorest population, in all the studies.

Socioeconomic inequality in preterm birth in four Brazilian birth cohort studies

ObjectiveTo analyze economic inequality (absolute and relative) due to family income in relation to the occurrence of preterm births in Southern Brazil. MethodsFour birth cohort studies were conducted in the years 1982, 1993, 2004, and 2011. The main exposure was monthly family income and the primary outcome was preterm birth. The inequalities were calculated using the slope index of inequality and the relative index of inequality, adjusted for maternal skin color, education, age, and marital status. ResultsThe prevalence of preterm births increased from 5.8% to approximately 14% (p-trend<0.001). Late preterm births comprised the highest proportion among the preterm births in all studies, although their rates decreased over the years. The analysis on the slope index of inequality demonstrated that income inequality arose in the 1993, 2004, and 2011 studies. After adjustment, only the 2004 study maintained the difference between the poorest and the richest subjects, which was 6.3 percentage points. The relative index of inequality showed that, in all studies, the poorest mothers were more likely to have preterm newborns than the richest. After adjustment for confounding factors, it was observed that the poorest mothers only had a greater chance of this outcome in 2004. ConclusionIn a final model, economic inequalities resulting from income were found in relation to preterm births only in 2004, although a higher prevalence of prematurity continued to be observed in the poorest population, in all the studies.

Ethnic Inequality in Preterm Birth

Preterm delivery is associated with lower health chances after birth. Women with a migration background often have a higher preterm risk (less than 37 gestational weeks) compared to the nonmigrant majority population. In Germany, little is known about the scope and causes for more adverse birth outcomes among immigrant women. Focusing primarily on two large migrant groups, that is first-generation Turkish and ethnic German immigrants, we examine whether these groups experience elevated preterm risk, and, if so, whether resources (e.g., economic, cultural, and social capital), health behavior (e.g., smoking during pregnancy and low utilization of prenatal care), and/or maternal constitution (height) help to explain the observed inequality relations. For the analysis, we estimate multiple logistic regression models based on the SOEP's newborn questionnaire (years 2003 – 2011). Our findings show that preterm birth is more prevalent among Turkish and ethnic German immigrants compared to women without a migration background. As expected, accounting for maternal constitution and resources decreases the preterm risk for all migrant groups, while – unexpectedly – a mother's and a partner's language proficiency is rather irrelevant. Health behavior during pregnancy then has no further explanatory power. After adjustment for all factors, no significant preterm differences between migrants and the nonmigrant majority population are observed. JEL-Classification: I10

O1-2.3 A family-based study of the nature of socioeconomic inequality in preterm birth and small for gestational age in Denmark around the turn of the millennium

IntroductionA large body of literature has reported associations between socioeconomic position (SEP) and adverse pregnancy outcomes even in affluent egalitarian welfare states. It is unclear if this is interpretable as...

Relative and Absolute Disparities in Preterm Birth Related to Neighborhood Education

To evaluate relative and absolute relationships between preterm birth (PTB) and neighborhood education over time. Live births in Québec, Canada, were obtained for 1990-1995, 1996-2000, and 2001-2006. Mean maternal education and proportion of females with no high school diploma were expressed as continuous cumulative rank scores for 10,923 neighborhoods. We estimated the relative hazard of PTB (<37 gestational weeks) for neighborhood education in each period by using Cox proportional hazards regression, accounting for individual education, age, marital status, birthplace, language, parity, infant sex, rurality, neighborhood income, and area clustering. Adjusted absolute differences in the prevalence of PTB between the most and least educated neighborhoods were calculated. PTB prevalence (6.1% overall) was greater in less-educated neighborhoods. Although PTB proportions increased over time in all neighborhoods, the increase was proportionately greater for less-educated areas. Hazards of PTB for neighborhood education were proportional over gestation. Depending on the indicator of neighborhood education and period, adjusted hazards of PTB were 10%-37% greater for the least relative to most educated neighborhoods, and prevalence percentage differences ranged from 0.6% to 1.9%. Associations persisted over time. Relative and absolute neighborhood educational inequalities in PTB, independent of individual education, were present and persistent over time.

Does Time Since Immigration Modify Neighborhood Deprivation Gradients in Preterm Birth? A Multilevel Analysis

Immigrants’ health is jointly influenced by their pre- and post-migration exposures, but how these two influences operate with increasing duration of residence has not been well-researched. We aimed to examine how the influence of maternal country of birth and neighborhood deprivation effects, if any, change over time since migration and how neighborhood effects among immigrants compare with those observed in the Canadian-born population. Birth data from Ontario hospital records (2002–2007) were linked with an official Canadian immigration database (1985–2000). The outcome measure was preterm birth. Neighborhoods were ranked according to a neighborhood deprivation index developed for Canadian urban areas and collapsed into tertiles of approximately equal size. Time since immigration was measured from the date of arrival to Canada to the date of delivery, ranging from 1 to 22 years. We used cross-classified random effect models to simultaneously account for the membership of births (N = 83,233) to urban neighborhoods (N = 1,801) and maternal countries of birth (N = 168). There were no differences in preterm birth between neighborhood deprivation tertiles among immigrants with less than 15 years of residence. Among immigrants with 15 years of stay or more, the adjusted absolute risk difference (ARD%, 95% confidence interval) between high-deprived (tertile 3) and low-deprived (tertile 1) neighborhoods was 1.86 (0.68, 2.98), while the ARD% observed among the Canadian-born (N = 314,237) was 1.34 (1.11, 1.57). Time since migration modifies the neighborhood deprivation gradient in preterm birth among immigrants living in Ontario cities. Immigrants reached the level of inequalities in preterm birth observed at the neighborhood level among the Canadian-born after 14 years of stay, but neighborhoods did not influence preterm birth among more recent immigrants, for whom the maternal country of birth was more predictive of preterm birth.

Increasing educational inequality in preterm birth in Québec, Canada, 1981–2006

BackgroundFew studies have evaluated the relationship between preterm birth (PTB) and maternal education over time. We sought to determine whether educational inequalities in PTB have increased in Québec, Canada.MethodsThe authors...

Association of socioeconomic position with maternal pregnancy and infant health outcomes in birth cohort studies from Brazil and the UK

BackgroundSocioeconomic inequalities in health outcomes are dynamic and vary over time. Differences between countries can provide useful insights into the causes of health inequalities. The study aims to compare the...

Social and racial inequalities in preterm births in Western Australia, 1984 to 2006

Preterm birth is associated with a range of childhood morbidities and in industrialised societies is the primary cause of infant mortality. Social and racial inequalities in preterm birth have been reported in North America, UK, Europe and New Zealand. This study utilised population-level data to investigate social and racial inequalities in preterm birth among Aboriginal and non-Aboriginal infants in Western Australia. All live, singleton births between 1984 and 2006 (n = 567 468) were included, and multilevel multivariable logistic regression was used to investigate relative differences in preterm infants between socio-economic groups. Aboriginal and non-Aboriginal infants were analysed separately. The prevalence of preterm births increased from 7.1% in 1984-88 to 7.5% in 1999-2003, before decreasing to 7.2% in 2004-06. Inequalities in preterm births between Aboriginal and non-Aboriginal infants increased over time, with the percentage of preterm births being almost twofold higher for Aboriginal infants (14.8%), compared with non-Aboriginal infants (7.6%). A significant portion of the disparity between Aboriginal and non-Aboriginal infants is attributable to parental socio-economic and demographic characteristics, though the disparity continues to persist even after adjustment for these factors. While the overall rates of preterm birth in Western Australia have remained fairly static over the last two decades, the disparity between Aboriginal and non-Aboriginal infants has increased and is now similar to inequalities seen 20 years ago. These findings highlight a major public health issue that should be of great concern, given the short- and long-term morbidities and complications associated with preterm birth.

Income-related and educational inequality in small-for-gestational age and preterm birth in Denmark and Finland 1987—2003

In this paper, we examine income- and education-related inequality in small-for-gestational age (SGA) and preterm birth in Denmark and Finland from 1987 to 2003 using concentration indexes (CIXs). From the national medical birth registries we gathered information on all births from 1987 to 2003. Information on highest completed maternal education and household income in the year preceding birth of the offspring was obtained for 1,012,400 births in Denmark and 499,390 in Finland. We then calculated CIXs for income- and education-related inequality in SGA and preterm birth. The mean household income-related inequality in SGA was -0.04 (95% confidence interval: -0.05, -0.04) in Denmark and -0.03 (-0.04, -0.02) in Finland. The maternal education-related inequality in SGA was -0.08 (-0.10, -0.06) in Denmark and -0.07 (-0.08, -0.06) in Finland. The income-related inequality in preterm birth was -0.03 (-0.03, -0.02) in Denmark and -0.03 (-0.04, -0.02) in Finland. The education-related inequality in preterm birth was -0.05 (-0.07, -0.04) in Denmark and -0.04 (-0.05, -0.03) in Finland. In Denmark, the income-related and education-related inequity in SGA increased over time. In Finland, the income-related inequality in SGA birth increased slightly, while education-related inequalities remained stable. Inequalities in preterm birth decreased over time in both countries. Denmark and Finland are examples of nations with free prenatal care and publicly financed obstetric care of high quality. During the period of study there were macroeconomic shocks affecting both countries. However, only small income- and education-related inequalities in SGA and preterm births during the period were observed.