Brighter children? The association between seasonality of birth and child IQ in a population-based birth cohort

The influence of early-life residential exposure to different vegetation types and paved surfaces on early childhood development: A population-based birth cohort study

BACKGROUND

Growing evidence suggests that exposure to green space is associated with improved childhood health and development, but the influence of different green space types remains relatively unexplored. In the present study, we investigated the association between early-life residential exposure to vegetation and early childhood development and evaluated whether associations differed according to land cover types, including paved land.

METHODS

Early childhood development was assessed via kindergarten teacher-ratings on the Early Development Instrument (EDI) in a large population-based birth cohort (n = 27,539) in Metro Vancouver, Canada. The residential surrounding environment was characterized using a high spatial resolution land cover map that was linked to children by six-digit residential postal codes. Early-life residential exposure (from birth to time of EDI assessment, mean age = 5.6 years) was calculated as the mean of annual percentage values of different land cover classes (i.e., total vegetation, tree cover, grass cover, paved surfaces) within a 250 m buffer zone of postal code centroids. Multilevel models were used to analyze associations between respective land cover classes and early childhood development.

RESULTS

In adjusted models, one interquartile range increase in total vegetation percentage was associated with a 0.33 increase in total EDI score (95% CI: 0.21, 0.45). Similar positive associations were observed for tree cover (β-coefficient: 0.26, 95% CI: 0.15, 0.37) and grass cover (β-coefficient: 0.12, 95% CI: 0.02, 0.22), while negative associations were observed for paved surfaces (β-coefficient: -0.35, 95% CI: -0.47, -0.23).

CONCLUSIONS

Our findings indicate that increased early-life residential exposure to vegetation is positively associated with early childhood developmental outcomes, and that associations may be stronger for residential exposure to tree cover relative to grass cover. Our results further indicate that childhood development may be negatively associated with residential exposure to paved surfaces. These findings can inform urban planning to support early childhood developmental health.

Neighborhood environmental exposures and incidence of attention deficit/hyperactivity disorder: A population-based cohort study

BACKGROUND

Emerging studies have associated low greenspace and high air pollution exposure with risk of child attention deficit/hyperactivity disorder (ADHD). Population-based studies are limited, however, and joint effects are rarely evaluated. We investigated associations of ADHD incidence with greenspace, air pollution, and noise in a population-based birth cohort.

METHODS

We assembled a cohort from administrative data of births from 2000 to 2001 (N ∼ 37,000) in Metro Vancouver, Canada. ADHD was identified by hospital records, physician visits, and prescriptions. Cox proportional hazards models were applied to assess associations between environmental exposures and ADHD incidence adjusting for available covariates. Greenspace was estimated using vegetation percentage derived from linear spectral unmixing of Landsat imagery. Fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) were estimated using land use regression models; noise was estimated using a deterministic model. Exposure period was from birth until the age of three. Joint effects of greenspace and PM_2.5 were analysed in two-exposure models and by categorizing values into quintiles.

RESULTS

During seven-year follow-up, 1217 ADHD cases were diagnosed. Greenspace was associated with lower incidence of ADHD (hazard ratio, HR: 0.90 [0.81-0.99] per interquartile range increment), while PM_2.5 was associated with increased incidence (HR: 1.11 [1.06-1.17] per interquartile range increment). NO₂ (HR: 1.01 [0.96, 1.07]) and noise (HR: 1.00 [0.95, 1.05]) were not associated with ADHD. There was a 50% decrease in the HR for ADHD in locations with the lowest PM_2.5 and highest greenspace exposure, compared to a 62% increase in HR in locations with the highest PM_2.5 and lowest greenspace exposure. Effects of PM_2.5 were attenuated by greenspace in two-exposure models.

CONCLUSIONS

We found evidence suggesting environmental inequalities where children living in greener neighborhoods with low air pollution had substantially lower risk of ADHD compared to those with higher air pollution and lower greenspace exposure.

Green CURIOCITY: a study protocol for a European birth cohort study analysing childhood heat-related health impacts and protective effects of urban natural environments

INTRODUCTION

The European climate is getting warmer and the impact on childhood health and development is insufficiently understood. Equally, how heat-related health risks can be reduced through nature-based solutions, such as exposure to urban natural environments, is unknown. Green CURe In Outdoor CITY spaces (Green CURIOCITY) will analyse how heat exposure during pregnancy affects birth outcomes and how long-term heat exposure may influence children's neurodevelopment. We will also investigate if adverse effects can be mitigated by urban natural environments. A final goal is to visualise intraurban patterns of heat vulnerability and assist planning towards healthier cities.

METHODS AND ANALYSIS

We will use existing data from the Human Early-Life Exposure cohort, which includes information on birth outcomes and neurodevelopment from six European birth cohorts. The cohort is linked to data on prenatal heat exposure and impact on birth outcomes will be analysed with logistic regression models, adjusting for air pollution and noise and sociobehavioural covariates. Similarly, impact of cumulative and immediate heat exposure on neurodevelopmental outcomes at age 5 will be assessed. For both analyses, the potentially moderating impact of natural environments will be quantified. For visualisation, Geographical information systems data will be combined to develop vulnerability maps, demonstrating urban 'hot spots' where the risk of negative impacts of heat is aggravated due to sociodemographic and land use patterns. Finally, geospatial and meteorological data will be used for informing GreenUr, an existing software prototype developed by the WHO Regional Office for Europe to quantify health impacts and augment policy tools for urban green space planning.

ETHICS AND DISSEMINATION

The protocol was approved by the Comité Ético de Investigación Clínica Parc de Salut MAR, Spain. Findings will be published in peer-reviewed journals and presented at policy events. Through stakeholder engagement, the results will also reach user groups and practitioners.

Association Between Season of Birth and Cognitive Aging in Older Adults: Pan-European Population-Based Study on 70,000 Individuals

BACKGROUND

Several early-life factors have been associated with higher risk of developing dementia. It is unclear whether season of birth (SOB) can affect cognitive aging in older adults or not.

OBJECTIVE

We aimed to study the association of SOB with the level of cognitive performance as well as with the rate of cognitive decline.

METHODS

We studied 70,203 individuals who participated in the Survey of Health, Aging and Retirement in Europe. Cognition was measured with tests on verbal fluency and immediate and delayed recall. We assessed the association of SOB with the level of cognitive performance using multiple linear regression and with the rate of cognitive decline using linear mixed-effects models.

RESULTS

When compared to individuals born in winter and adjusted for sociodemographic and health-related characteristics, being born in summer was associated with a higher level of delayed recall (B 0.05; 95%CI 0.01 to 0.09) and verbal fluency (B 0.15; 95%CI 0.00 to 0.29) and being born in fall with a higher level of immediate recall (B 0.04; 95%CI 0.01 to 0.08) and verbal fluency (B 0.15; 95%CI 0.01 to 0.29). Individuals born in summer had a higher yearly decline in delayed recall (B -0.005; 95%CI -0.009 to 0.000), while the scores in delayed recall in participants born in spring showed an inverse trend (B 0.005; 95%CI 0.000 to 0.010).

CONCLUSION

Individuals born in winter seem to carry a life-long disadvantage in a lower level of cognitive performance; however, being born in winter does not seem to affect the rate of cognitive decline.

Birth month and infant gross motor development: Results from the Japan Environment and Children's Study (JECS)

The association between birth month and neurodevelopmental or psychiatric disorders has been investigated in a number of previous studies; however, the results have been inconsistent. This study investigated the association between birth month and child gross motor development at 6 and 12 months of age in a large cohort of infants (n = 72,203) participating in the Japan Environment and Children’s Study (JECS). Gross motor development was assessed using the Ages and Stages Questionnaire (ASQ-3). At 6 months and 12 months, 20.7% and 14.2%, respectively, had ASQ-3 indications of gross motor problems. Birth month was strongly associated with gross motor development at both time points, particularly at 6 months. Summer-born infants had the worst outcomes at both 6 months and 12 months of age. This outcome applied to the ASQ-3 score itself and to the adjusted Relative Risk (aRR), with the highest aRRs (relative to January-born) among August-born (aRR 2.51; 95%CI 2.27–2.78 at 6 months), and June-born (aRR 1.84; 95%CI 1.63–2.09 at 12 months). Boys had better scores than girls both at 6 and 12 months of age. We speculate that seasonal factors—such as maternal vitamin D deficiency and influenza infection—affecting the fetus in early pregnancy might account for the findings.

Season of birth and sugary beverages are predictors of Raven's Standard Progressive Matrices Scores in adolescents

To investigate factors associated with cognitive functioning in healthy adolescents, a school-based cross-sectional study was conducted on 1370 adolescents aged 11–16 years that were randomly selected from all governorates of Kuwait. Raven’s Standard Progressive Matrices (SPM), a non-verbal test of intelligence, was used to measure cognitive functioning of the study participants. Data on predictors of cognitive functioning were collected from parents and adolescents. Weight and height of the participants were measured in a standardized manner and blood samples were tested in an accredited laboratory under strict measures of quality control. In multivariable linear regression analysis, factors that showed significant association with the SPM score were gender (p = 0.002), season of birth (p = 0.009), place of residence (p < 0.001), father’s (p < 0.001) and mother’s (p = 0.025) educational level, type of housing (p < 0.001), passive smoking at home (p = 0.031), sleeping hours during weekends (p = 0.017), students’ educational level (p < 0.001) and the frequency of consumption of sugary drinks (p < 0.001). The link between cognitive functioning and season of birth seems to be robust in various geographical locations including the Middle East. The association between sugary drinks and cognitive functioning highlights the importance of diet independently of obesity and support efforts to reduce consumption of sugary drinks among children.

Associations between vitamin D status in pregnancy and offspring neurodevelopment: a systematic literature review

CONTEXT

Vitamin D plays an important role in the development of the brain, which is one of the earliest fetal organs to develop. Results from epidemiological studies investigating associations between maternal levels of vitamin D during pregnancy and offspring neurodevelopment are mixed and inconclusive.

OBJECTIVE

This systematic review of studies that examined vitamin D levels in pregnancy and offspring neurodevelopment used 3 specific domains-timing of exposure during pregnancy trimesters, neurodevelopmental outcomes, and offspring age at assessment of outcomes-to determine whether vitamin D status in pregnancy is associated with offspring neurodevelopment.

DATA SOURCES

A search of the Embase, PsychInfo, Scopus, and The Cochrane Library databases in September 2017 and February 2018 identified 844 articles, of which 46 were retrieved for full-text assessment.

STUDY SELECTION

Eligibility criteria were used to select studies. All authors examined the studies, and consensus was reached through discussion. Results were divided according to the 3 domains.

DATA EXTRACTION

Authors examined the studies independently, and data from eligible studies were extracted using a modified version of the Cochrane data collection form. Using the modified Downs and Black checklist, 2 authors assessed the quality of the studies independently and were blinded to each other's assessment. Consensus was reached upon discussion and with the involvement of the third author.

RESULTS

Fifteen observational studies were included. Vitamin D in pregnancy was associated with offspring language and motor skills in young children. Associations persisted into adolescence, and results were not dependent on the timing of vitamin D exposure during pregnancy. No supplementation studies were identified.

CONCLUSIONS

There is some evidence that low vitamin D status in pregnancy is associated with offspring language and motor development, particularly in young children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42017078312.

Birth month is associated with learning capacity in childhood in Northeast China

It is difficult to evaluate long-term ventilation and indoor-outdoor temperature variation on-site in the birth residence so as to investigate their associations with learning capacity from childhood through adolescence. Here, we conducted a questionnaire-based retrospective cohort study in ten schools from two northeast China cities with warm summers and severe cold winters when residences had very low air exchange rates. Scores for Chinese, Mathematics, and English in the final exams of the summer semester in June 2018 were collected to evaluate learning capacity. We surveyed 6238 students aged 14.7 (SD: 2.1) years old. Using the 2nd quarter (April-May-June) birth as reference, 4th quarter (October-November-December) birth consistently was significantly associated with lower scores in Chinese in bivariate (β, 95%CI: -3.2, -4.3 to -2.0) and multivariate (-1.8, -2.4 to -0.8) linear regression analyses. Stratified sub-analyses showed significant associations for male (-2.4, -3.7 to -1.1), urban (-2.4, -3.4 to -1.4), and primary students (-2.9, -4.5 to -1.4). Since household ventilation and indoor-outdoor temperature variation had great differences between the 2nd and 4th quarter of year, our results suggest that these two factors in the birth residence could be associated with learning capacity in childhood, especially for male and primary students in northeast China.

Polygenic risk for schizophrenia and season of birth within the UK Biobank cohort

BACKGROUND

There is strong evidence that people born in winter and in spring have a small increased risk of schizophrenia. As this 'season of birth' effect underpins some of the most influential hypotheses concerning potentially modifiable risk exposures, it is important to exclude other possible explanations for the phenomenon.

METHODS

Here we sought to determine whether the season of birth effect reflects gene-environment confounding rather than a pathogenic process indexing environmental exposure. We directly measured, in 136 538 participants from the UK Biobank (UKBB), the burdens of common schizophrenia risk alleles and of copy number variants known to increase the risk for the disorder, and tested whether these were correlated with a season of birth.

RESULTS

Neither genetic measure was associated with season or month of birth within the UKBB sample.

CONCLUSIONS

As our study was highly powered to detect small effects, we conclude that the season of birth effect in schizophrenia reflects a true pathogenic effect of environmental exposure.

Birth seasonality and risk of autism spectrum disorder

Season of birth has been hypothesized to be a risk factor for autism spectrum disorder (ASD). However, the evidence has been mixed and limited due to methodological challenges. We examine ASD birth trends for 5,464,628 births across 5 countries. ASD birth prevalence data were obtained from the International Collaboration for Autism Registry Epidemiology database, including children born in Denmark, Finland, Norway, Sweden, and Western Australia. Empirical mode decomposition and cosinor modeling were used to assess seasonality. We show seasonal variation in ASD births for the countries of Finland and Sweden. There was a modest increase in risk for children born in the fall and a modest decrease in risk for children born in the spring. Solar radiation levels around conception and the postnatal period were inversely correlated with seasonal trends in ASD risk. In the first multinational study of birth seasonality of ASD, there was evidence supporting the presence of seasonal trends in Finland and Sweden. The observations that risk was highest for fall births (i.e., conceived in the winter) and lowest for spring births (i.e., conceived in the summer), and sunlight levels during critical neurodevelopmental periods explained much of the seasonal trends, are consistent with the hypothesis that a seasonally fluctuating risk factor may influence risk of ASD.

Seasonality of depressive symptoms during pregnancy

Various risk factors have been identified for antepartum depression. This study evaluated seasonal influences on antepartum depressive symptoms. Data of 2,438 pregnant women on current depressive symptoms was obtained from a large-scale cross-sectional study in The Netherlands. Most women were screened during the first trimester. Depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS) and dichotomized using ≥ 9 as cut-off score. The seasonal relationship between antepartum depressive symptoms and the month of assessment was estimated by fitting a sinusoidal curve to the data. A total of 323 women (13.2%) scored above cut-off. In the full sample, we found no significant evidence for seasonal influences on depressive symptoms after adjusting for confounders. Additionally, we found that the seasonal influence was obscured by the modification of the effect by current treatment status. In women untreated for psychiatric complaints, we found a minimum of depressive symptomatology in September and a maximum in March. In women treated for psychiatric complaints we found a minimum of depressive symptomatology in December and a maximum in June. Thus, the effects of seasonality are apparent, but opposite in treated and untreated women. However, health professionals should be aware of depressive symptoms the whole year through.