Neighbourhood income and neonatal, postneonatal and sudden infant death syndrome (SIDS) mortality in Canada, 1991-2005

County-Level Structural Vulnerabilities in Maternal Health and Geographic Variation in Infant Mortality

OBJECTIVE

To evaluate whether community factors that differentially affect the health of pregnant people contribute to geographic differences in infant mortality across the US.

STUDY DESIGN

This retrospective cohort study sought to characterize the association of a novel composite measure of county-level maternal structural vulnerabilities, the Maternal Vulnerability Index (MVI), with risk of infant death. We evaluated 11 456 232 singleton infants born at 22 0 of 7 through 44 6 of 7 weeks' gestation from 2012 to 2014. Using county-level MVI, which ranges from 0 to 100, multivariable mixed effects logistic regression models quantified associations per 20-point increment in MVI, with odds of death clustered at the county level and adjusted for state, maternal, and infant covariates. Secondary analyses stratified by the social, physical, and health exposures that comprise the overall MVI score. Outcome was also stratified by cause of death.

RESULTS

Rates of death were higher among infants from counties with the greatest maternal vulnerability (0.62% in highest quintile vs 0.32% in lowest quintile, [P < .001]). Odds of death increased 6% per 20-point increment in MVI (aOR: 1.06, 95% CI 1.04, 1.07). The effect estimate was highest with theme of Mental Health and Substance Abse (aOR 1.08; 95% CI 1.06, 1.09). Increasing vulnerability was associated with 6 of 7 causes of death.

CONCLUSIONS

Community-level social, physical, and healthcare determinants indicative of maternal vulnerability may explain some of the geographic variation in infant death, regardless of cause of death. Interventions targeted to county-specific maternal vulnerabilities may reduce infant mortality.

Sociodemographic and regional differences in neonatal and infant mortality in Switzerland in 2011-2018: the Swiss National Cohort

BACKGROUND AND AIMS

Despite a well-funded healthcare system with universal insurance coverage, Switzerland has one of the highest neonatal and infant mortality rates among high-income countries. Identifying avoidable risk factors targeted by evidence-based policies is a public health priority. We describe neonatal and infant mortality in Switzerland from 2011 to 2018 and explore associations with neonatal- and pregnancy-related variables, parental sociodemographic information, regional factors and socioeconomic position (SEP) using data from a long-term nationwide cohort study.

METHODS

We included 680,077 live births, representing 99.3% of all infants born in Switzerland between January 2011 and December 2018. We deterministically linked the national live birth register with the mortality register and with census and survey data to create a longitudinal dataset of neonatal- and pregnancy-related variables; parental sociodemographic information, such as civil status, age, religion, education, nationality; regional factors, such as urbanity, language region; and the Swiss neighbourhood index of socioeconomic position (Swiss-SEP index). Information on maternal education was available for a random subset of 242,949 infants. We investigated associations with neonatal and infant mortality by fitting multivariable Poisson regression models with robust standard errors. Several sensitivity analyses assessed the robustness of our findings.

RESULTS

Overall, neonatal mortality rates between 2011 and 2018 were 3.0 per 1000 live births, with regional variations: 3.2 in German-speaking, 2.4 in French-speaking and 2.1 in Italian-speaking Switzerland. For infant mortality, the rates were 3.7 per 1000 live births overall, and 3.9 in the German-speaking, 3.3 in the French-speaking and 2.9 in the Italian-speaking region. After adjusting for sex, maternal age, multiple birth and birth rank, neonatal mortality remained significantly associated with language region (adjusted rate ratio [aRR] 0.72, 95% confidence interval [CI]: 0.64-0.80 for the French-speaking region and aRR 0.66, 95% CI: 0.51-0.87 for the Italian-speaking region vs German-speaking region), with marital status (aRR 1.55, 95% CI: 1.40-1.71 for unmarried vs married), nationality (aRR 1.40, 95% CI: 1.21-1.62 for non-European Economic Area vs Swiss) and the Swiss-SEP index (aRR 1.17, 95% CI: 1.00-1.36 for lowest vs highest SEP quintile). In the subset, we showed a possible association of neonatal mortality with maternal education (aRR 1.24, 95% CI: 0.95-1.61 for compulsory vs tertiary education).

CONCLUSION

We provide detailed evidence about the social patterning of neonatal and infant mortality in Switzerland and reveal important regional differences with about 30% lower risks in French- and Italian-speaking compared with German-speaking regions. Underlying causes for such regional differences, such as cultural, lifestyle or healthcare-related factors, warrant further exploration to inform and provide an evidence base for public health policies.

Morbidity and mortality of newborns born to immigrant and nonimmigrant females residing in low-income neighbourhoods

BACKGROUND

Living in low-income neighbourhoods and being an immigrant are each independently associated with adverse neonatal outcomes, but it is unknown if disparities exist in the neonatal period for children of immigrant and nonimmigrant females living in low-income areas. We sought to compare the risk of severe neonatal morbidity and mortality (SNMM) between newborns of immigrant and nonimmigrant mothers who resided in low-income neighbourhoods.

METHODS

This population-based cohort study used administrative data for females residing in low-income urban neighbourhoods in Ontario, who had an in-hospital, singleton live birth at 20-42 weeks' gestation, from 2002 to 2019. We defined immigrant status as nonrefugee immigrant or nonimmigrant, further detailed by country of birth and duration of residence in Ontario. The primary outcome was a SNMM composite (with 16 diagnoses, including neonatal death and 7 neonatal procedures as indicators), arising within 0-27 days after birth. We estimated relative risks (RRs) and 95% confidence intervals (CIs) using modified Poisson regression with generalized estimating equations.

RESULTS

Our cohort included 148 050 and 266 191 live births among immigrant and nonimmigrant mothers, respectively. Compared with newborns of non-immigrant females, SNMM was less frequent among newborns of immigrant females (49.7 v. 65.6 per 1000 live births), with an adjusted RR of 0.76 (95% CI 0.74 to 0.79). The most frequent SNMM indicator was receipt of ventilatory support. Relative to neonates of nonimmigrant females, the risk of SNMM was highest among those of immigrants from Jamaica (adjusted RR 1.14, 95% CI 1.05 to 1.23) and Ghana (adjusted RR 1.20, 95% CI 1.05 to 1.38), and lowest among those of immigrants from China (adjusted RR 0.44, 95% CI 0.40 to 0.48). Among immigrants, the risk of SNMM declined with shorter duration of residence before the index birth.

INTERPRETATION

Within low-income urban areas, newborns of immigrant females had an overall lower risk of SNMM than those of nonimmigrant females, with considerable variation by maternal birthplace and duration of residence. Initiatives should focus on improving preconception health and perinatal care within subgroups of females residing in low-income neighbourhoods.

Sudden unexpected infant death risk profiles in the first month of life

BACKGROUND

Limited improvement in current SUID rates requires further identification of its characteristics, including age-specific risk patterns.

OBJECTIVE

Compare SUID risk factors in the first week versus the remainder in the first month of life.

DESIGN/METHODS

We compared maternal and infant data from New Jersey databases for SUID from 2000 to 2015 in infants ≥ 34 weeks GA in the two groups.

RESULTS

In the period studied, 123 died in the first 27 days, 24 before seven. Deaths in the first week had a higher percentage of mothers with post-High School education (OR 3.50, CI: 1.38-8.87) and a primary Cesarean section delivery (OR 4.0, CI: 1.39-11.49), and a smaller percentage with inadequate prenatal care (OR 0.36, CI: 0.14, 0.94). A smaller percentage of first-week deaths had mothers who smoked during pregnancy or identified as Black, non-Hispanic, but these findings did not reach significance (p < .08 and p < .09, respectively).

CONCLUSIONS

SUID in the first week and the first month of life is rare. However, despite a limited sample size, data suggest that even within the first month of life, there are differences in risk patterns for SUID based on age at death. Age-specific profiles may lead to new hypotheses regarding causality and more refined risk-reduction guidelines and warrant further study.

The global burden of sudden infant death syndrome from 1990 to 2019: a systematic analysis from the Global Burden of Disease study 2019

BACKGROUND

Sudden infant death syndrome (SIDS) still remains one of the leading causes of infant death worldwide, especially in high-income countries. To date, however, there is no detailed information on the global health burden of SIDS.

AIMS

To characterize the global disease burden of SIDS and its trends from 1990 to 2019 and to compare the burden of SIDS according to the socio-demographic index (SDI).

DESIGN

Systematic analysis based on the Global Burden of Disease (GBD) 2019 data.

METHODS

Epidemiological data of 204 countries from 1990 to 2019 were collected via various methods including civil registration and vital statistics in the original GBD study. Estimates for mortality and disease burden of SIDS were modeled. Crude mortality and mortality rates per 100 000 population were analyzed. Disability-adjusted life years (DALYs) and DALY rates were also assessed.

RESULTS

In 2019, mortality rate of SIDS accounted for 20.98 [95% Uncertainty Interval, 9.15-46.16] globally, which was a 51% decrease from 1990. SIDS was most prevalent in Western sub-Saharan Africa, High-income North America and Oceania in 2019. The burden of SIDS was higher in males than females consistently from 1990 to 2019. Higher SDI and income level was associated with lower burden of SIDS; furthermore, countries with higher SDI and income had greater decreases in SIDS burden from 1990 to 2019.

CONCLUSIONS

The burden of SIDS has decreased drastically from 1990 to 2019. However, the improvements have occurred disproportionately between regions and SDI levels. Focused preventive efforts in under-resourced populations are needed.

Factors associated with age of death in sudden unexpected infant death

Aim

This study aimed to systematically analyse the pregnancy, birth and demographic‐related factors associated with age of death in sudden unexpected infant death (SUID).

Methods

Data were analysed from the Centers for Disease Control and Prevention's Cohort Linked Birth/Infant Death data set (2011‐2013; 11 737 930 live births). SUID was defined as deaths from sudden infant death syndrome, ill‐defined causes, or accidental suffocation and strangulation in bed. There were 9668 SUID cases (7‐364 days; gestation >28 weeks; 0.82/1000 live births). The odds of death at different ages were compared to determine which variables significantly affect the SUID age of death.

Results

Forty‐three features indicated a significant change in age of death with two main patterns: (a) younger chronologic age at death was associated with maternal smoking and factors associated with lower socio‐economic status, and (b) older age was associated with low birthweight, prematurity and admission to the neonatal intensive care unit. However, when age was corrected for gestation, these factors were associated with younger age.

Conclusion

Factors that varied with age of death are well‐documented risk factors for SUID. The majority of these risk factors were associated with younger age at death after allowing for gestational age at birth.

A new record linkage for assessing infant mortality rates in Ontario, Canada

OBJECTIVE

Infant mortality statistics for Canada have routinely omitted Ontario-Canada's most populous province-as a high proportion of Vital Statistics infant death registrations could not be linked with their corresponding Vital Statistics live birth registrations. We assessed the feasibility of linking an alternative source of live birth information with infant death registrations.

METHODS

All infant deaths occurring before 365 days of age registered in Ontario's Vital Statistics in 2010-2011 were linked with birth records in the Canadian Institute for Health Information's hospitalization database. Crude birthweight-specific and gestational age-specific infant mortality rates were calculated, and rates examined according to maternal and infant characteristics.

RESULTS

Of 1311 infant death registrations, only 47 (3.6%) could not be linked to a hospital birth record. The overall crude infant mortality rate was 4.7 deaths per 1000 live births (95% CI, 4.4 to 4.9), the same as previously reported for the rest of Canada in 2011. Infant mortality was higher in women < 20 years (5.8 per 1000 live births) and ≥ 40 years (5.9 per 1000 live births), and lowest among those aged 25-29 years (3.9 per 1000 live births). Infant mortality was notably higher in the lowest (5.1 per 1000 live births) residential income quintile than the highest (3.4 per 1000 live births).

CONCLUSION

Use of birth hospitalization records resulted in near-complete linkage of all Vital Statistics infant death registrations. This approach could enhance the conduct of representative surveillance and research on infant mortality when direct linkage of live birth and infant death registrations is not achievable.

Maternal Social and Economic Factors and Infant Morbidity, Mortality, and Congenital Anomaly: Are There Associations?

Experiences during infancy create durable and heritable patterns of social deprivation and illness producing health disparities. This retrospective cohort study of 71 836 infants from Winnipeg, Manitoba, assessed associations between maternal social and economic factors and infant mortality, morbidity, and congenital anomaly. This study found that newborn and postneonatal hospital readmissions are inversely associated with geography. Additionally, social context, including maternal history of child abuse, is associated with infant postneonatal hospital readmissions. Geography and education are associated with infant mortality. Income was not associated with infant mortality or morbidity following adjustment for social support. Interestingly, congenital anomaly rates are 1.2 times more common among 2 parent families and male infants. Understanding associations between infant health and maternal social and economic factors may contribute to interventions and policies to improve health equity.

New Frameworks for Understanding Sudden Unexpected Deaths in Infancy (SUDI) in Socially Vulnerable Families

THEORETICAL PRINCIPLES

Sociological frameworks may enhance understanding of the complex and multidimensional nature of disadvantage, which is prevalent among families who experience Sudden Unexpected Death in Infancy (SUDI).

PHENOMENA ADDRESSED

SUDI is the largest category of postneonatal death and largely associated with the social determinants of health. The highly successful 'Back to Sleep' campaign has resulted in a more than 85% decrease in SUDI. However, social inequalities have accompanied this decrease, and the burden of SUDI now lies with the most disadvantaged and socially vulnerable families. A considerable body of research on the phenomena of SUDI and disadvantage has been published over the last decade, demonstrating the widening social gradient in SUDI, and the importance in recognising structural factors and the multifactorial nature of disadvantage. Gaps in understanding of risk factors and scepticism about the received wisdom of health professionals have emerged as central themes in understanding why socially vulnerable families may adopt unsafe infant care practices. The direct impact of social disadvantage on infant care has also been recognised.

RESEARCH LINKAGES

The translation of epidemiological findings regarding SUDI risk into public health recommendations for health professionals and families alike has to date focused on eliminating individual level risk behaviours. Unfortunately, such a model largely ignores the broader social, cultural, and structural contexts in which such behaviours occur. Translating the new knowledge offered by sociological frameworks and the principles of behavioural economics into evidence based interventions may assist in the reduction of SUDI mortality in our most socially vulnerable families.

Infant mortality among the Canadian-born offspring of immigrants and non-immigrants in Canada: a population-based study

BACKGROUND

Adult immigrants in Canada have a survival advantage over their Canadian-born counterparts. It is unknown whether migrants are able to transmit their survival advantage to their Canadian-born children.

METHODS

Neonatal and postneonatal mortality between the Canadian-born population and 12 immigrant subgroups were compared using 1990-2005 linked birth-infant death records. Age-at-death specific mortality rates and rate differences were calculated by nativity status and maternal birthplace. A chi-square statistic was used to compare group differences in maternal sociodemographic characteristics. Multivariate survival analysis was used to estimate the effect of maternal birthplace on neonatal and postneonatal mortality, net of maternal sociodemographic and infant characteristics.

RESULTS

Overall, immigrants had lower rates of neonatal and postneonatal mortality than the Canadian-born population. But the adjusted risk of neonatal mortality was higher for Sub-Saharan African (hazard ratio [HR] = 1.32; 95 % confidence interval [CI] = 1.05, 1.66), Haitian (HR = 2.29, 95 % CI = 1.90, 2.76), non-Spanish Caribbean (HR = 1.38; 95 % CI = 1.01, 1.89), and Pakistani (HR = 1.87; 95 % CI = 1.31, 2.68) migrants relative to Canadian-born women. There were fewer significant disparities in postneonatal death, with higher adjusted risks of mortality observed for Pakistani (HR = 2.67, 95 % CI = 1.77, 4.02) and Haitian (HR = 1.41, 95 % CI = 1.02, 1.97) migrants only.

CONCLUSION

Inequalities in infant mortality are more concentrated in the neonatal period. Contingent on surviving the first 27 days after birth, the infants of most immigrants (except those from Haiti and Pakistan) have the same chances of survival as the infants of Canadian-born women. Improvements in prenatal care and access to postpartum care may reduce disparities in infant mortality.

Temporal trends in social disparities in maternal smoking and breastfeeding in Canada, 1992-2008

A steady decrease in maternal smoking during pregnancy and a steady increase in breastfeeding rates have been observed in Canada in the past two decades. However, the extent to which all socioeconomic classes have benefited from this progress is unknown. Therefore, this study was undertaken to determine: (1) whether progress achieved benefited the entire population or was limited to specific strata; and (2) whether disparities among strata decreased, stayed the same, or increased over time. We used data from the National Longitudinal Survey of Children and Youth, which enrolled children aged 0-3 years between 1994 and 2008. Data collected at entry was analyzed in a cross-sectional manner. Between birth years 1992-1996 and 2005-2008, smoking during pregnancy decreased from 11.5 % (95 % CI 10.0-13.0 %) to 5.2 % (95 % CI 4.1-6.3 %) among mothers with a college or university degree and from 43.0 % (95 % CI 38.8-47.2 %) to 38.6 % (95 % CI 32.9-44.2 %) among those with less than secondary education. During the same period, the rate of breastfeeding initiation increased from 83.8 % (95 % CI 81.9-85.6 %) to 91.5 % (95 % CI 90.2-92.8 %) among mothers with a college or university degree and from 63.1 % (95 % CI 58.9-67.4 %) to 74.7 % (95 % CI 69.8-79.7 %) among those with less than secondary education. The risks of smoking and of not breastfeeding remained significantly higher in the least educated category than in the most educated throughout the study period, and these associations remained statistically significant after controlling for maternal age. Gaps between the least and the most educated mothers narrowed for breastfeeding but widened for smoking during pregnancy.

Sudden infant death syndrome and residential altitude

BACKGROUND

Theories of sudden infant death syndrome (SIDS) suggest hypoxia is a common pathway. Infants living at altitude have evidence of hypoxia; however, the association between SIDS incidence and infant residential altitude has not been well studied.

METHODS

We performed a retrospective cohort study by using data from the Colorado birth and death registries from 2007 to 2012. Infant residential altitude was determined by geocoding maternal residential address. Logistic regression was used to determine adjusted association between residential altitude and SIDS. We evaluated the impact of the Back to Sleep campaign across various altitudes in an extended cohort from 1990 to 2012 to assess for interaction between sleep position and altitude.

RESULTS

A total of 393 216 infants born between 2007 and 2012 were included in the primary cohort (51.4% boys; mean birth weight 3194 ± 558 g). Overall, 79.6% infants resided at altitude <6000 feet, 18.5% at 6000 to 8000 feet, and 1.9% at >8000 feet. There were no meaningful differences in maternal characteristics across altitude groups. Compared with residence <6000 feet, residence at high altitude (>8000 feet), was associated with an adjusted increased risk of SIDS (odds ratio 2.30; 95% confidence interval 1.01-5.24). Before the Back to Sleep campaign, the incidence of SIDS in Colorado was 1.99/1000 live births and dropped to 0.57/1000 live births after its implementation. The Back to Sleep campaign had similar effect across different altitudes (P = .45).

CONCLUSIONS

Residence at high altitude was significantly associated with an increased adjusted risk for SIDS. Impact of the Back to Sleep campaign was similar across various altitudes.