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Adequate thyroid hormone availability is required for normal brain development. Studies have found associations between prenatal exposure to air pollutants and thyroid hormones in pregnant women and newborns. We aimed to examine associations of trimester-specific residential exposure to common air pollutants with congenital hypothyroidism (CHT). All term infants born in Israel during 2009–2015 were eligible for inclusion. We used data on CHT from the national neonatal screening lab of Israel, and exposure data from spatiotemporal air pollution models. We used multivariable logistic regression models to estimate associations of exposures with CHT, adjusting for ethnicity, socioeconomic status, geographical area, conception season, conception year, gestational age, birth weight, and child sex. To assess residual confounding, we used postnatal exposures to the same pollutants as negative controls. The study population included 696,461 neonates. We found a positive association between third-trimester nitrogen oxide exposure and CHT (per interquartile-range change, odds ratio = 1.23, 95% confidence interval: 1.08, 1.41) and a similar association for nitrogen dioxide. There was no evidence of residual confounding or bias by correlation among exposure periods for these associations.

Congenital hypothyroidism (CH) is the most common preventable cause of mental retardation and delayed growth in children. Several prenatal and environmental factors might be associated with the disease.To determine the prevalence and risk factors of permanent CH and transient congenital hypothyroidism (TCH) in Israel.We conducted a retrospective analysis of the Israeli national newborn screening program database from 2011 to 2015. Chi-square and logistic regression were used to assess the association of the demographic and gestational factors with the CH and TCH.Of the 889,033 live births screened between 2011 and 2015, 860 were diagnosed with CH (9.76 per 10,000 live births) and 298 with TCH (3.35 per 10,000 live births). In multivariate analyses, CH was positively associated with female sex, gestational ages38 or39 weeks, birth weight3000 grams, and winter birth. A decreased risk of TCH was detected in Arabs and neonates from high socioeconomic areas. An increased risk was independently associated with gestational ages38 weeks, low birth weight, and winter birth.Several demographic, gestational, and geographical factors are associated with the development of CH and TCH. Future studies are needed to further investigate the pathogenesis in Israel.

BACKGROUND: Residual confounding is a major concern for causal inference in observational studies on air pollution–autism spectrum disorder (ASD) associations. This study is aimed at assessing confounding in these associations using negative control exposures. METHODS: This nested case–control study included all children diagnosed with ASD (detected through 31 December 2016) born during 2007-2012 in Israel and residing in the study area (N= 3,843), and matched controls of the same age (N= 38,430). We assigned individual house-level exposure estimates for each child. We estimated associations using logistic regression models, mutually adjusted for all relevant exposure periods (pre-pregnancy, pregnancy, and postnatal). We assessed residual confounding using post-outcome negative control exposure at age 28-36 months. RESULTS: In mutually adjusted models we observed positive associations with ASD for postnatal exposures to NOx (odds ratio [OR] per interquartile range, 95% confidence interval [CI]: 1.19, 1.02-1.38) and NO(2) (1.20, 1.00-1.43), and gestational exposure to PM(2.5-10) (1.08, 1.01-1.15). The result for the negative control period was 1.04, 0.99-1.10 for PM(2.5,) suggesting some residual confounding, but no associations for PM(2.5-10) (0.98, 0.81-1.18), NOx (1.02, 0.84-1.25) or NO(2) (0.98, 0.81-1.18), suggesting no residual confounding. CONCLUSIONS: Our results further support a hypothesized causal link with ASD that is specific to postnatal exposures to traffic-related pollution.

Studies have shown that air pollution exposures during pregnancy are associated with an increased risk of autism spectrum disorder (ASD) in children, and the risk appears to be greater for boys. However, studies assessing gestational windows of susceptibility have been mostly limited by trimesters.We identified sensitive windows of exposure to regional air pollution and risk of ASD and examined sex differences in a large birth cohort.This population-based retrospective cohort study included 294,937 mother-child pairs with singleton deliveries in Kaiser Permanente Southern California (KPSC) hospitals from 2001 to 2014. Children were followed using electronic medical records until clinical ASD diagnosis, non-KPSC membership, death, or 31 December 2019, whichever came first. Weekly mean fine particulate matter [PM with an aerodynamic diameter ofThere were 5,694 ASD diagnoses (4,636 boys, 1,058 girls). SensitiveExposures to

Using records from the National Insurance Institute of Israel, we recognized all children with autism spectrum disorders (ASD, N = 8072) or hearing loss (HL, N = 2231) born in Israel between 2005 and 2010. Typical developed children were taken from a random 20% sample of children born during the same years (N = 227,492). Analyses were adjusted for year of birth, population group, parental ages, parental education, child birth order and peripherality. Working women, who gave birth to children with either ASD or HL, were at increased risk of not maintaining their working status over the 5 years after birth. There is a decreased ratio between household wage after and before birth, in families with children with either ASD or HL.

Childhood exposure to nitrogen oxides (NOx) is considered a risk factor for the onset of asthma. However, associations of this exposure with other atopic diseases and factors that modify this association are less clear. We aimed to study associations between exposure to NOx and the prevalence of atopic diseases in Israeli adolescents using a cross-sectional design. The study population comprised all Israeli-born adolescents whose medical status was evaluated for mandatory military recruitment during 1967–2017 (n = 2,523,745), of whom 5.9% had prevalent asthma. We based the exposure assessments on a land-use regression model and estimated associations using multivariable logistic regression models. Across all periods, mean exposure to NOx from birth to adolescence was associated with prevalent asthma at the examination in a dose-response manner, with an odds ratio for the upper quintile of 1.61 (95% CI: 1.56–1.67), in comparison to the lowest quintile. Associations were stronger in males and in lower socioeconomic strata. We found the strongest associations for asthma with comorbid rhinitis, with an almost twofold increase in the odds of upper versus lower quintile of exposure (odds ratio = 1.96, 95% CI: 1.82–2.11). Rhino-conjunctivitis and allergic atopic dermatitis suggested a possible threshold level with NOx. Capsule Summary: Research indicates that half of the global population will suffer from an allergic condition at some point in life. Childhood exposure to nitrogen oxides is a risk factor for the onset of asthma. The association between exposure and allergic diseases other than asthma is unclear. We demonstrate a strong, dose-response relationship between exposure and a group of allergic outcomes, using data comprising 2.5 million subjects over 50 years. The large health benefits from clean air should motivate governments to prioritize mitigation measures.

BACKGROUND AND AIM: The global prevalence of childhood overweight and obesity has risen dramatically in recent years. Previous studies found associations between rapid infant weight gain and risk o...

Studies assessing the associations between prenatal air pollution exposures and birth outcomes commonly use maternal addresses at the time of delivery as a proxy for residency throughout pregnancy. Yet, in large-scale epidemiology studies, maternal addresses commonly originate from an administrative source.This study aimed to examine the use of population registry addresses to assign exposure estimations and to evaluate the impact of inaccurate addresses on exposure estimates and association measures of prenatal exposures with congenital hypothyroidism.We used morbidity data for congenital hypothyroidism from the national program for neonatal screening for 2009-2015 and address data from two sources: population registry and hospital records. We selected neonates with geocoded addresses from both sources (N = 685,491) and developed a comparison algorithm for these addresses. Next, we assigned neonates with exposures from ambient air pollution of PM and NOWe found that most of the exposure differences between neonates with addresses from both sources were around zero and had a leptokurtic distribution density, with most values being zero. Additionally, associations between exposure and congenital hypothyroidism were comparable, regardless of address source and when we limited the model to neonates with identical addresses.We found that ignoring residential inaccuracies results in only a small bias of the associations towards the null. These results strengthen the validity of addresses from population registries for exposure assessment, when detailed residential data during pregnancy are not available.

Haifa Bay Area (HBA) contains Israel’s principal industrial area, and there are substantial public concerns about health effects from its emissions. We aimed to examine associations between exposure to air pollution from HBA industrial area with prevalent asthma and other atopic diseases at age 17. This is a cross-sectional study. The study population included all adolescents born in Israel and whose medical status was evaluated for mandatory military recruitment by the Israeli medical corps during 1967–2017. We analyzed prevalent asthma, allergic rhinitis, atopic dermatitis, and rhinoconjunctivitis. We estimated exposure to industrial air pollution by a kriging interpolation of historical SO2 observations and adjusted the associations to the year of birth, SES, school orientation, and traffic pollution. The study population included n = 2,523,745 adolescents, among which 5.9% had prevalent asthma and 4.6% had allergic rhinitis. Residency in HBA was associated with a higher adjusted risk of asthma, compared with non-HBA residency. Still, this association was limited to the three lowest exposure categories, while the highest exposure group had the lowest adjusted risk. Sensitivity analyses and other atopic diseases presented similar results. These results do not provide support for causal relationships between HBA industry-related emissions and prevalent atopic diseases.

Background Studies of the effects of prenatal environmental exposures on postnatal outcomes are particularly vulnerable to live birth bias; i.e., the bias that arises from the necessary restriction of the analysis to live births when that is influenced by both the exposure under study A and unmeasured factors U that also affect the outcome. Objectives In the context of a recent publication of nitrogen dioxide ( NO 2 ) and autism spectrum disorder (ASD) that found an odds ratio (OR) of 0.77 per 5.85 ppb NO 2 during pregnancy, we aimed to examine what parameters would be needed to account for this protective association through live birth bias. Methods We simulated the magnitude of bias under two selection mechanisms and when both mechanisms co-occur, assuming a true null effect. Simulation input parameters were based on characteristics of the original study and a range of plausible values for the prevalence of unmeasured factor U and the ORs for the selection effects (i.e., the effects of NO 2 and U on loss and of U on ASD). Each scenario was simulated 1,000 times. Results We found that the magnitude of bias was small when NO 2 and U independently influenced pregnancy loss (collider-stratification without interaction), was stronger when NO 2 -induced loss preferentially occurred in U = 1 (depletion of susceptibles), and was strongest when both mechanisms worked together. For example, ORs of 3.0 for NO 2 -loss , U -loss, U -ASD, and U prevalence = 0.75 yielded NO 2 -ASD ORs per 5.85 ppb NO 2 of 0.95, 0.89, and 0.75 for the three scenarios, respectively. The bias is amplified with multiple U s , yielding ORs as low as 0.51. Discussion Our simulations illustrate that live birth bias may lead to exposure-outcome associations that are biased downward, where the extent of the bias depends on the fetal selection mechanism, the strength of that selection, and the prevalence of U. https://doi.org/10.1289/EHP7961.

The adverse health effects of inhaled particulate matter (PM) are global concern. Yet, in general, estimating the exposure to PM is challenging due to the sparsity of standard air quality monitoring stations and the low accuracy of dispersion models when high spatial resolution is required. The city of Elad, Israel, is situated less than 1 km from the Migdal Tzedek stone quarry, and public concerns were raised regarding the impact of the quarry's PM emissions on the city air quality. This work describes a year-long campaign of continuous measurements of particle number concentration (PNC) in few locations in the city and its vicinity, using a network of low cost optical particle counters (OPCs). To assess the possible impact of the quarry on the city we examined the OPCs' accuracy, coherency, and their capability to detect the quarry's impact on the PNC levels in the city. Using PNC time series in two size channels from a network of five nodes, PM10 and PM2.5 records from a nearby reference air quality monitoring station, and meteorological data, we could conclude that the quarry's impact on the city was small relative to the background PNC levels. Yet, more importantly, this work demonstrates the use of a network of low cost OPCs for responding to an environmental query for which the sparse standard air quality monitoring observations were not sufficient. The trade-offs between deployment of a network of cheap low-quality instruments and the use of a single high-end device are discussed.

Satellite-based particulate matter (PM) models provide spatially and temporally resolved estimations, allowing greater spatial-temporal coverage compared to sparse ground monitoring stations. The spatio-temporal resolution of these models can be improved using aerosol optical depth (AOD) products from various satellite platforms with different overpass times which can capture possible changes in diurnal aerosol concentrations. Israel is characterized by diverse geo-climatic regions and it is subjected to frequent dust storms events. Our goal was to estimate PM10 and PM2.5 concentrations in Israel on daily and intra-daily (mean PM around the Aqua and Terra overpasses) temporal resolutions and to assess the differences between these time windows. A hybrid modeling approach that consists of three stages was used enabling spatially continuous PM estimations at 1 × 1 km spatial resolution. The model was calibrated on a daily basis applying a mixed modeling approach using MODIS-based MAIAC AOD and various spatial and temporal predictors. It was found that in certain urban areas the measured and estimated PM concentrations during the satellite overpass (Terra or Aqua) were higher than the mean daily PM. The models performed well showing cross-validated R2 that ranged between 0.82 and 0.92. Mean estimated PM for the study period (2005–2015) during days with no dust events showed different spatial patterns for the daily and intra-daily estimations and revealed areas in Israel that are affected by high PM concentrations (mainly industrial or dense urban areas). Estimations from these models are useful for epidemiological research and might contribute to environmental regulatory purposes by focusing the efforts of PM pollution reduction at the identified polluted areas.

Background: Accumulating evidence suggest that perinatal exposure to particulate matter (PM), nitrogen dioxide (NO2) and nitrogen oxides (NOx), is associated with risk of autism spectrum disorder (...

Background: Preterm birth is a major determinant of adverse health consequences, and early term births are also associated with increased risk of various outcomes. In light of climate change, the effect of ambient temperature on earlier delivery is an important factor to consider. Several studies have focused on associations of ambient air temperature (Ta) on preterm birth, but few have examined associations with early term births. Aims: To investigate the association of prenatal exposure to Ta with preterm birth (

Exposure to airborne particles is a risk factor of many short- and long-term health effects. Most epidemiological studies include estimates of exposure to ambient particles, however, people living in developed countries spend most of their time indoors. This work presents an analysis of a field campaign of simultaneous measurements of indoor-to-outdoor particle number concentrations (PNCs) in Israel. Fine and coarse PNCs were continuously measured using Dylos DC1700 devices from October 2016 to October 2017. The median outdoor PNC was always higher than the indoor PNC in all the five sampling locations. Outdoor fine PNCs peak during the night and experience a trough in the afternoon. The median of the fine indoor-to-outdoor PNC ratio (IOR) was 0.83, with an inter quartile range (IQR) of 0.59. The median of the coarse IOR was 0.70, with an IQR of 0.77. Lower IORs were experienced at night than during the day, with a daily peak (IOR &gt, 1) around noon. Information about the IOR in different regions and seasons may help epidemiologists and policy makers understand the true health effects of particulate air pollution, and correct their exposure estimations such that they account for indoor exposure as well.

Using records from the National Insurance Institute of Israel, we recognized all children with autism spectrum disorders (ASD, N = 8072) or hearing loss (HL, N = 2231) born in Israel between 2005 and 2010. Typical developed children were taken from a random 20% sample of children born during the same years (N = 227,492). Analyses were adjusted for year of birth, population group, parental ages, parental education, child birth order and peripherality. Working women, who gave birth to children with either ASD or HL, were at increased risk of not maintaining their working status over the 5 years after birth. There is a decreased ratio between household wage after and before birth, in families with children with either ASD or HL.

Air pollution in the urban environment is a major concern. The ambient concentrations depend on the levels of transboundary imported pollution, the intensity of local sources and the prevailing atmospheric conditions. This work studies the relative impact of two atmospheric variables–atmospheric stability and regional scale turbulence–in determining the air pollution concentrations. We considered a setting (downtown Haifa, Israel) impacted by a large variety of sources, emitting pollutants with different chemical attributes and atmospheric life times. We found that traffic accounts for most of the locally produced pollution in the study location. However, the meteorological factors can overwhelm its impact and dictate the concentrations. The switch from stable to convective conditions and the more vigorous daytime wind are associated with a premature end of the morning peak concentrations that result from rush hour emissions of NOx, Black Carbon (BC) and ultra–fine particles. It results in daytime concentration which are lower than (winter) or equal to (summer) those at night, in spite of the much lower night–time traffic volumes. Similar, albeit weaker, impact was detected in the benzene and toluene concentrations. Sources outside the study area are responsible for most of the CO, PM1 and PM2.5 concentrations but during winter nights, characterised by strong atmospheric stability and low turbulence, their concentrations are elevated due to the local emissions. We developed a diagnostic statistical nonlinear model for the pollutant concentrations, which points to a stronger association of the atmospheric stability with the concentrations during stable conditions but turbulence dominating during convective conditions. Our findings explain the relatively low overall concentrations of locally emitted pollutants in the study area but warn of the potential for high concentrations during night–time in locations with comparable meteorological conditions.

A recent analysis found that exposure to air pollution during specific weeks of pregnancy was negatively associated with risk of autism spectrum disorder (ASD) when mutually adjusted for postnatal air-pollution exposure. In this commentary, we describe 2 possible selection-bias processes that might lead to such results, both related to live-birth bias (i.e., the inevitable restriction of the analyzed sample to live births). The first mechanism is described using a directed acyclic graph and relates to the chance of live birth being a common consequence of both exposure to air pollution and another risk factor of ASD. The second mechanism involves preferential depletion of fetuses susceptible to ASD in the higher air-pollution exposure group. We further discuss the assumptions underlying these processes and their causal structures, their plausibility, and other studies where similar phenomena might have occurred.

Accumulating evidence suggests that perinatal air pollutant exposures are associated with increased risk of autism spectrum disorder (ASD), but evidence for traffic pollutants outside the United States is inconclusive. We assessed the association between nitrogen dioxide, a traffic pollution tracer, and risk of ASD. We conducted a nested case-control study among the entire population of children born during 2005–2009 in the central coastal area of Israel. Cases were identified through the National Insurance Institute of Israel (n = 2,098). Controls were a 20% random sample of the remaining children (n = 54,191). Exposure was based on an optimized dispersion model. We estimated adjusted odds ratios and 95% confidence intervals using logistic regression and a distributed-lag model. In models mutually adjusted for the 2 periods, the odds ratio per 5.85-parts per billion (ppb) increment of nitrogen dioxide exposure during pregnancy (median, 16.8 ppb; range, 7.5–31.2 ppb) was 0.77 (95% confidence interval: 0.59, 1.00), and the odds ratio for exposure during the 9 months after birth was 1.40 (95% confidence interval: 1.09, 1.80). A distributed-lag model revealed reduced risk around week 13 of pregnancy and elevated risk around week 26 after birth. These findings suggest that postnatal exposure to nitrogen dioxide in Israel is associated with increased odds of ASD, and prenatal exposure with lower odds. The latter may relate to selection effects.

Data indicate that the prevalence of autism spectrum disorder (ASD) may be increasing and that it varies geographically. We investigated associations between residential location and ASD in the children of Nurses’ Health Study II (United States) participants in order to generate hypotheses about social and environmental factors related to etiology or diagnosis. Analyses included data on 13,507 children born during 1989–1999 (486 with ASD). We explored relationships between ASD and residential location both at birth and at age 6 years (i.e., closer to average age at diagnosis). Generalized additive models were used to predict ASD odds across the United States. Children born in New England were 50% more likely to be diagnosed with ASD compared with children born elsewhere in the United States. Patterns were not explained by geographic variation in maternal age, birth year, child's sex, community income, or prenatal exposure to hazardous air pollutants, indicating that spatial variation is not attributable to these factors. Using the residential address at age 6 years produced similar results; however, areas of significantly decreased ASD odds were observed in the Southeast, where children were half as likely to have ASD. These results may indicate that diagnostic factors are driving spatial patterns; however, we cannot rule out the possibility that other environmental factors are influencing distributions.

Low birth weight (

Autism spectrum disorder (ASD) trends have been gaining a great deal of focus in recent decades, as many studies worldwide show a continued rise in incidence rates. Many researchers have begun analyzing socioeconomic data in relation to ASD in an effort to understand the source of these changing rates and the role of awareness and access to resources. In this study, we aim to contribute to this body of knowledge by examining incidence time trends of ASD in Israel according to socioeconomic factors. While similar studies have been conducted in Israel, this study is the first of its kind to include the total population. Individual-level data from the Israeli National Insurance Institute were used to determine cumulative incidence of ASD, first for the total population, and then stratified by population group and income categories. Multivariable logistic regression models were fit to analyze associations between income category and both risk of ASD and risk of ASD diagnosis in later age. A total of 431,348 children were examined in this study, with 13,841 cases of ASD. The cumulative incidence of all children aged 8 in 2015 was 0.64%, marking an increase compared to previous literature from Israel. Within our study period, ASD incidence followed this increase until the 2009 birth cohort, where it began to stabilize. Our initial findings from regression models showed strong positive associations between household income and ASD incidence, as expected. After factoring in population group, however, the elevated ASD incidence rates in the highest income bracket decreased. Autism Res 2019, 12: 1870-1879. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study contributes comprehensive and current data on ASD trends overtime in Israel and introduces crucial insights regarding the impact of socioeconomic factors on ASD diagnoses. We found a rise in ASD that began leveling off in 2009. We identified more ASD diagnoses occurring in families with higher incomes and in the General Population, pointing to the important role of sociodemographic factors on ASD diagnoses.

Purpose Studies indicate an apparent sharp increasing trend in autism spectrum disorder (ASD) incidence and prevalence worldwide. This nationwide study aims at depicting ASD prevalence distribution in Israel in both space and time. Methods Based on data from Israel National Insurance Institute, the study population included all children born in Israel 2000–2011 (n = 1,786,194), of whom 11,699 (0.655%) were subsequently diagnosed with ASD (until December 31, 2016). Prevalence was calculated and mapped by dividing the number of ASD cases within each year of birth by the number of births during that year, for each spatial unit, and similarly for several spatiotemporal levels of aggregation. Results ASD prevalence varies substantially across different geographic areas in Israel, with considerably higher prevalence concentrated in central Israel. Strong associations were found between locality-level socioeconomic index, ethnicity, and peripherality and ASD prevalence, and even after adjustment for them, excess prevalence for ASD still persisted in certain localities. No spatial dependence of prevalence, with and without adjustment for the locality-level variables, was found (Moran's I = −0.000546, −0.00335, respectively). Conclusions Our findings provide important insights regarding health disparities affecting ASD diagnosis, directing further health policy intervention and further research.

Autism Spectrum Disorder (ASD) is a complex condition with early childhood onset, characterized by a set of common behavioral features. The etiology of ASD is not yet fully understood; however, it reflects the interaction between genetics and environment. While genetics is now a well-established risk factor, several data support a contribution of the environment as well. This paper summarizes the conclusions of a consensus conference focused on the potential pathogenetic role of environmental factors and on their interactions with genetics. Several environmental factors have been discussed in terms of ASD risk, namely advanced parental age, assisted reproductive technologies, nutritional factors, maternal infections and diseases, environmental chemicals and toxicants, and medications, as well as some other conditions. The analysis focused on their specific impact on three biologically relevant time windows for brain development: the periconception, prenatal, and early postnatal periods. Possible protective factors that might prevent or modify an ASD trajectory have been explored as well. Recommendations for clinicians to reduce ASD risk or its severity have been proposed. Developments in molecular biology and big data approaches, which are able to assess a large number of coexisting factors, are offering new opportunities to disentangle the gene–environment interplay that can lead to the development of ASD.

Background: Relatively few studies have examined the association between extreme ambient air temperatures (Ta) and pregnancy outcomes. We investigated the association between Ta, term low birth wei...

BACKGROUND. Traffic-related air pollution has been linked to multiple adverse pregnancy outcomes. However, few studies have examined pregnancy loss, targeting losses identified by hospital records, a large limitation as it does not capture events not reported to the medical system. METHODS. We used a novel variation of the time-series design to determine the association, and identify the critical window of vulnerability, between week-to-week traffic-related air pollution and conceptions resulting in live births, using nitrogen dioxide (NO(2)) as a traffic emissions tracer. We used information from all live births recorded at Beth Israel Deaconess Medical Center in Boston, MA, USA (2000–2013) and all live births in Tel Aviv District, Israel (2010–2013). RESULTS: In Boston (68,969 live births), the strongest association was during the 15(th) week of gestation; for every 10 ppb of NO(2) increase during that week we observed a lower rate of live births (rate ratio [RR]=0.87; 95% confidence interval [CI]: 0.78–0.97), using live birth-identified conceptions to infer pregnancy losses. In the Tel Aviv District (95,053 live births), the strongest estimate was during the 16(th) gestational week gestation (RR=0.82; 95%CI: 0.76–0.90 per 10 ppb of NO(2)). CONCLUSIONS: Using weekly conceptions ending in live birth rather than identified pregnancy losses, we comprehensively analyzed the relationship between air pollution and all pregnancy loss throughout gestation. The observed results, with remarkable similarity in two independent locations, suggest that higher traffic-related air pollution levels are associated with pregnancy loss, with strongest estimates between the 10(th) and 20(th) gestational weeks.

Background/aim Findings regarding air pollution and of autism spectrum disorder (ASD) are inconsistent. A recent publication testing associations between exposure to NO2 and autism used a distributed lag model with ASD data and weekly NO2 exposures from Israel in order to identify windows of vulnerability. When mutually adjusted, prenatal associations reached a negative peak around week 15 of gestation. Methods A directed acyclic graph (DAG) was built to represent the causal structure and the underlying assumptions needed for live birth bias to create biassed negative associations between prenatal exposure to air pollution and risk of ASD. Results Live-birth bias could arise from the fact that ASD can only be assessed in live-born children, and many pregnancies are lost and do not end in a live birth. This inevitable selection of only live births into the analysis may lead to bias of the observed association from the actual causal association if a) air pollution is a risk factor for pregnancy loss (this assumption is supported by some literature); and b) there are other factors (‘U’, likely unmeasured, even unknown) that influence both pregnancy loss and ASD. A possible ‘U’ is prenatal stress, which is implicated in both pregnancy loss and ASD. Selection of live births opens the backdoor path ASD Pregnancy Loss Conclusion Live-birth bias can create a negative association between air pollution and ASD. This bias has implications for all air pollution-ASD studies, and it may also be relevant to other neurodevelopmental conditions.

Population-based data on the magnitude and determinants of Autism Spectrum Disorder (ASD) recurrence risk in families with an index case are rare. We examined whether short birth gaps and other birth spacing factors increase the risk of recurrence, using a population-based cohort study in Israel. We examined records of younger siblings of index cases (children diagnosed with ASD), and estimated recurrence risk and its determinants. Overall, 5.25% (261/4976) of younger siblings were diagnosed with ASD. Younger siblings with birth gaps less than two years of their index case had significantly higher risk compared to the rest (odds ratio = 1.66, 95% CI 1.25–2.22). The association remained significant in models adjusted for sex of the index cases and their younger siblings, ethnicity, parental ages and birth order (odds ratio = 1.43, CI 1.03–1.96). This finding suggests that short birth gaps from the index case increase the risk of ASD among younger siblings.

It is hypothesized that vitamin D insufficiency in athletes might negatively affect sport performance. The objective of this study was to examine the effect of vitamin D3 supplementation on physical performance of adolescent swimmers with vitamin D insufficiency. Fifty-three adolescent competitive swimmers with vitamin D insufficiency (serum 25-hydroxyvitamin-D concentrations (25(OH)D)3 or placebo for 12 weeks. Swimming performance at several speeds, arm-grip strength, and one-legged balance, were measured before and after supplementation. The age-adjusted changes in performance variables during the study were compared between groups. 25(OH) D concentrations at study end were significantly higher in the vitamin group compared with the placebo group (29.6 ± 6.5ng/ml vs. 20.3 ± 4.2ng/ml, p < .001), yet only 48% of the vitamin group became vitamin D sufficient with this dosing. No between-group differences were found in the changes of the performance variables tested. No significant differences in performance were found between participants that became vitamin D sufficient, and those who did not. No significant correlation was found between the change in serum 25(OH)D and ageadjusted balance, strength or swimming performance at study end. Vitamin D3 supplementation that raised serum 25(OH)D concentrations by a mean of 9.3ng/ml above placebo in adolescent swimmers with vitamin D insufficiency, did not improve physical performance more than placebo.