Prenatal Exposure to Tobacco and Cannabis in Six Race/Ethnicity Groups during the First Three Years after Legalization of Cannabis for Recreational Use in California

There are known health concerns linked to prenatal tobacco and cannabis exposures. This study aims to objectively determine the level of exposure to tobacco and cannabis in pregnant individuals from six race/ethnicity groups (Black, Hispanic, Asian Indian, Native American, Vietnamese, and White) in the first three years following legalization of recreational marijuana use in 2018 in California. We used a cross-sectional sample of prenatal screening program participants (2018-2020) from southern and central California (N = 925). Exposures were estimated by a lab analysis of cotinine (tobacco) and 11-hydroxy-Δ9-tetrahydrocannabinol (OH-THC, cannabis) in banked serum. Disparities in tobacco exposure were evident, with Black subjects experiencing the highest smoking rate (16%) followed by Native American (10%) and White (8%) subjects, and ≤2% among Hispanic, Asian Indian, and Vietnamese subjects. Environmental tobacco exposure generally showed a similar pattern of exposure to tobacco smoking across race/ethnicity groups. Cannabis detection ranged from 5% among Hispanic subjects to 12% and 13% among White and Black subjects, respectively, and was higher among tobacco users and those exposed to environmental tobacco smoke than those with no cotinine detected. Tobacco and cannabis exposure were generally greatest in younger subjects and those with indices of a lower economic status; however, among Black subjects, cannabis exposure was greatest in older subjects and those with a higher socioeconomic status. Race/ethnicity, age, and socioeconomic factors can inform targeting of high-exposure groups for intervention.

CFTR gene variants, air pollution, and childhood asthma in a California Medicaid population

Carriers of the cystic fibrosis transmembrane conductance regulator (CFTR) gene ("carriers") have been found to have an increased risk of persistent asthma. However, it is unclear at what level of CFTR function this risk exists and whether it is modified by asthmogens, such as air pollution. We conducted a retrospective cohort study of children born in California between July 2007 and December 2013, linking CFTR genotype data from the California newborn screening program to Medicaid claims records through March 17, 2020 to identify asthma cases, and to air pollution data from CalEnviroScreen 3.0 to identify levels of particulate matter with diameter 2.5 microns or smaller (PM_2.5 ). Log-binomial regression models for asthma risk were fitted, adjusting for race/ethnicity and sex. Compared to population controls, carriers had higher risk of asthma (adjusted risk ratio (aRR) = 1.29, 95% confidence interval (CI): 0.98, 1.69; p < 0.1). Other non-CF-causing variants on the second allele did not appear to further increase risk. Genotypes with the greatest asthma risk were F508del with an intron 10 T7 or (TG)11T5 in trans (aRR=1.52, 95% CI: 1.10, 2.12). This association was higher among children living in areas at or above (aRR = 1.80) versus below (aRR = 1.37) the current national air quality standard for PM_2.5 , though this difference was not statistically significant (p_interaction  > 0.2). These results suggest carriers with CFTR functional levels between 25% and 45% of wildtype are at increased risk of asthma. Knowledge of CFTR genotype in asthmatics may be important to open new CFTR-related treatment options for these patients.

Missed Cystic Fibrosis Newborn Screening Cases due to Immunoreactive Trypsinogen Levels below Program Cutoffs: A National Survey of Risk Factors

Testing immunoreactive trypsinogen (IRT) is the first step in cystic fibrosis (CF) newborn screening. While high IRT is associated with CF, some cases are missed. This survey aimed to find factors associated with missed CF cases due to IRT levels below program cutoffs. Twenty-nine states responded to a U.S-wide survey and 13 supplied program-related data for low IRT false screen negative cases (CFFN) and CF true screen positive cases (CFTP) for analysis. Rates of missed CF cases and odds ratios were derived for each factor in CFFNs, and two CFFN subgroups, IRT above ("high") and below ("low") the CFFN median (39 ng/mL) compared to CFTPs for this entire sample set. Factors associated with "high" CFFN subgroup were Black race, higher IRT cutoff, fixed IRT cutoff, genotypes without two known CF-causing variants, and meconium ileus. Factors associated with "low" CFFN subgroup were older age at specimen collection, Saturday birth, hotter season of newborn dried blood spot collection, maximum ≥ 3 days laboratories could be closed, preterm birth, and formula feeding newborns. Lowering IRT cutoffs may reduce "high" IRT CFFNs. Addressing hospital and laboratory factors (like training staff in collection of blood spots, using insulated containers during transport and reducing consecutive days screening laboratories are closed) may reduce "low" IRT CFFNs.

A profile and review of findings from the Early Markers for Autism study: unique contributions from a population-based case-control study in California

Background

The Early Markers for Autism (EMA) study is a population-based case–control study designed to learn more about early biologic processes involved in ASD.

Methods

Participants were drawn from Southern California births from 2000 to 2003 with archived prenatal and neonatal screening specimens. Across two phases, children with ASD (n = 629) and intellectual disability without ASD (ID, n = 230) were ascertained from the California Department of Developmental Services (DDS), with diagnoses confirmed according to DSM-IV-TR criteria based on expert clinical review of abstracted records. General population controls (GP, n = 599) were randomly sampled from birth certificate files and matched to ASD cases by sex, birth month and year after excluding individuals with DDS records. EMA has published over 20 papers examining immune markers, endogenous hormones, environmental chemicals, and genetic factors in association with ASD and ID. This review summarizes the results across these studies, as well as the EMA study design and future directions.

Results

EMA enabled several key contributions to the literature, including the examination of biomarker levels in biospecimens prospectively collected during critical windows of neurodevelopment. Key findings from EMA include demonstration of elevated cytokine and chemokine levels in maternal mid-pregnancy serum samples in association with ASD, as well as aberrations in other immune marker levels; suggestions of increased odds of ASD with prenatal exposure to certain endocrine disrupting chemicals, though not in mixture analyses; and demonstration of maternal and fetal genetic influence on prenatal chemical, and maternal and neonatal immune marker and vitamin D levels. We also observed an overall lack of association with ASD and measured maternal and neonatal vitamin D, mercury, and brain-derived neurotrophic factor (BDNF) levels.

Limitations

Covariate and outcome data were limited to information in Vital Statistics and DDS records. As a study based in Southern California, generalizability for certain environmental exposures may be reduced.

Conclusions

Results across EMA studies support the importance of the prenatal and neonatal periods in ASD etiology, and provide evidence for the role of the maternal immune response during pregnancy. Future directions for EMA, and the field of ASD in general, include interrogation of mechanistic pathways and examination of combined effects of exposures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00429-7.

Maternal immune response and air pollution exposure during pregnancy: insights from the Early Markers for Autism (EMA) study

BACKGROUND

Perinatal exposure to air pollution and immune system dysregulation are two factors consistently associated with autism spectrum disorders (ASD) and other neurodevelopmental outcomes. However, little is known about how air pollution may influence maternal immune function during pregnancy.

OBJECTIVES

To assess the relationship between mid-gestational circulating levels of maternal cytokines/chemokines and previous month air pollution exposure across neurodevelopmental groups, and to assess whether cytokines/chemokines mediate the relationship between air pollution exposures and risk of ASD and/or intellectual disability (ID) in the Early Markers for Autism (EMA) study.

METHODS

EMA is a population-based, nested case-control study which linked archived maternal serum samples collected during weeks 15-19 of gestation for routine prenatal screening, birth records, and Department of Developmental Services (DDS) records. Children receiving DDS services for ASD without intellectual disability (ASD without ID; n = 199), ASD with ID (ASD with ID; n = 180), ID without ASD (ID; n = 164), and children from the general population (GP; n = 414) with no DDS services were included in this analysis. Serum samples were quantified for 22 cytokines/chemokines using Luminex multiplex analysis technology. Air pollution exposure for the month prior to maternal serum collection was assigned based on the Environmental Protection Agency's Air Quality System data using the maternal residential address reported during the prenatal screening visit.

RESULTS

Previous month air pollution exposure and mid-gestational maternal cytokine and chemokine levels were significantly correlated, though weak in magnitude (ranging from - 0.16 to 0.13). Ten pairs of mid-pregnancy immune markers and previous month air pollutants were significantly associated within one of the child neurodevelopmental groups, adjusted for covariates (p < 0.001). Mid-pregnancy air pollution was not associated with any neurodevelopmental outcome. IL-6 remained associated with ASD with ID even after adjusting for air pollution exposure.

CONCLUSION

This study suggests that maternal immune activation is associated with risk for neurodevelopmental disorders. Furthermore, that prenatal air pollution exposure is associated with small, but perhaps biologically relevant, effects on maternal immune system function during pregnancy. Additional studies are needed to better evaluate how prenatal exposure to air pollution affects the trajectory of maternal immune activation during pregnancy, if windows of heightened susceptibility can be identified, and how these factors influence neurodevelopment of the offspring.

Maternal Vitamin D Levels During Pregnancy in Association With Autism Spectrum Disorders (ASD) or Intellectual Disability (ID) in Offspring; Exploring Non-linear Patterns and Demographic Sub-groups

Increasing vitamin D deficiency and evidence for vitamin D's role in brain and immune function have recently led to studies of neurodevelopment; however, few are specific to autism spectrum disorder (ASD) and vitamin D in pregnancy, a likely susceptibility period. We examined this in a case-control study of 2000-2003 Southern Californian births; ASD and intellectual disability (ID) were identified through the Department of Developmental Services and controls from birth certificates (N = 534, 181, and 421, respectively, in this analysis). Total 25-Hydroxyvitamin D (25(OH)D) was measured in mid-pregnancy serum, categorized as deficient (<50 nmol/L), insufficient (50-74 nmol/L), or sufficient (≥75 nmol/L, referent category), and examined continuously (per 25 nmol/L). Crude and adjusted odds ratios (AORs) and 95% confidence intervals (95% CI) were calculated. Non-linearity was examined with cubic splines. AORs (95% CI) for ASD were 0.79 (0.49-1.3) for maternal deficiency (9.5%), 0.93 (0.68-1.3) for insufficiency (25.6%), and 0.95 (0.86, 1.05) for linear continuous 25(OH)D. Results were similarly null for ASD with or without ID, and ID only. Interactions were observed; non-Hispanic whites (NHW) (AOR = 0.82, 95% CI = 0.69-0.98) and males (AOR = 0.89, 95% CI = 0.80-0.99) had protective associations for ASD with continuous 25(OH)D. A positive association with ASD was observed in females (AOR = 1.40, 95% CI = 1.06-1.85). With splines, a non-linear inverted j-shaped pattern was seen overall (P = 0.009 for non-linearity), with the peak around 100 nmol/L; a non-linear pattern was not observed among NHW, females, nor for ID. Our findings from a large study of ASD and prenatal vitamin D levels indicate that further research is needed to investigate non-linear patterns and potentially vulnerable sub-groups. LAY SUMMARY: We studied whether mothers' vitamin D levels during pregnancy were related to their children having autism (or low IQ) later. Low vitamin D levels were not related to greater risk of autism or low IQ in children overall. With higher levels of mothers' vitamin D, risk of autism went down in boys, but went up in girls. Risk of autism also went down in children of non-Hispanic white mothers with higher vitamin D levels, but we did not find a relation in other race/ethnic groups.

Out-of-Hospital Cardiac Arrests and Wildfire-Related Particulate Matter During 2015-2017 California Wildfires

Background

The natural cycle of large‐scale wildfires is accelerating, increasingly exposing both rural and populous urban areas to wildfire emissions. While respiratory health effects associated with wildfire smoke are well established, cardiovascular effects have been less clear.

Methods and Results

We examined the association between out‐of‐hospital cardiac arrest and wildfire smoke density (light, medium, heavy smoke) from the National Oceanic Atmospheric Association's Hazard Mapping System. Out‐of‐hospital cardiac arrest data were provided by the Cardiac Arrest Registry to Enhance Survival for 14 California counties, 2015–2017 (N=5336). We applied conditional logistic regression in a case‐crossover design using control days from 1, 2, 3, and 4 weeks before case date, at lag days 0 to 3. We stratified by pathogenesis, sex, age (19–34, 35–64, and ≥65 years), and socioeconomic status (census tract percent below poverty). Out‐of‐hospital cardiac arrest risk increased in association with heavy smoke across multiple lag days, strongest on lag day 2 (odds ratio, 1.70; 95% CI, 1.18–2.13). Risk in the lower socioeconomic status strata was elevated on medium and heavy days, although not statistically significant. Higher socioeconomic status strata had elevated odds ratios with heavy smoke but null results with light and medium smoke. Both sexes and age groups 35 years and older were impacted on days with heavy smoke.

Conclusions

Out‐of‐hospital cardiac arrests increased with wildfire smoke exposure, and lower socioeconomic status appeared to increase the risk. The future trajectory of wildfire, along with increasing vulnerability of the aging population, underscores the importance of formulating public health and clinical strategies to protect those most vulnerable.

Genetic Contributions to Maternal and Neonatal Vitamin D Levels

Vitamin D is essential for several physiological functions and biological processes. Increasing levels of maternal vitamin D are required throughout pregnancy as a unique source of vitamin D for the fetus, and consequently maternal vitamin D deficiency may result in several adverse outcomes in newborns. However, the genetic regulation of vitamin D in pregnancy and at birth is not yet well understood. We performed genome-wide association studies of maternal midgestational serum-derived and neonatal blood-spot-derived total 25-hydroxyvitamin D from a case-control study of autism spectrum disorder (ASD). We identified one fetal locus (rs4588) significantly associated with neonatal vitamin D levels in the GC gene, encoding the binding protein for the transport and function of vitamin D. We also found suggestive cross-associated loci for neonatal and maternal vitamin D near immune genes, such as CXCL6-IL8 and ACKR1 We found no interactions with ASD. However, when including a set of cases with intellectual disability but not ASD (N = 179), we observed a suggestive interaction between decreased levels of neonatal vitamin D and a specific maternal genotype near the PKN2 gene. Our results suggest that genetic variation influences total vitamin D levels during pregnancy and at birth via proteins in the vitamin D pathway, but also potentially via distinct mechanisms involving loci with known roles in immune function that might be involved in vitamin D pathophysiology in pregnancy.

An Exploratory Examination of Neonatal Cytokines and Chemokines as Predictors of Autism Risk: The Early Markers for Autism Study

BACKGROUND

The identification of an early biomarker for autism spectrum disorder (ASD) would improve the determination of risk, leading to earlier diagnosis and, potentially, earlier intervention and improved outcomes.

METHODS

Data were generated from the Early Markers for Autism study, a population-based case-control study of prenatal and neonatal biomarkers of ASD. Newborn bloodspots of children with ASD (n = 370), children with developmental delay (n = 140), and general population (GP) controls (n = 378) were analyzed for 42 different immune markers using a Luminex multiplex platform. Comparisons of immune marker concentrations between groups were examined using logistic regression and partial least squares discriminant analysis.

RESULTS

Children with ASD had significantly increased neonatal levels of interleukin-6 (IL-6) and IL-8 compared with GP controls. An increase in IL-8 was especially significant in the ASD group with early onset compared with the GP group, with an adjusted odds ratio of 1.97 (95% confidence interval, 1.39-2.83; p = .00014). In addition, children with ASD had significantly elevated levels of eotaxin-1, interferon-γ, and IL-12p70 relative to children with developmental delay. We observed no significant differences in levels of immune markers between the developmental delay and GP groups.

CONCLUSIONS

Elevated levels of some inflammatory markers in newborn bloodspots indicated a higher degree of immune activation at birth in children who were subsequently diagnosed with ASD. The data from this exploratory study suggest that with further expansion, the development of neonatal bloodspot testing for cytokine/chemokine levels might lead to the identification of biomarkers that provide an accurate assessment of ASD risk at birth.

Newborn vitamin D levels in relation to autism spectrum disorders and intellectual disability: A case-control study in california

Vitamin D deficiency has been increasing concurrently with prevalence of autism spectrum disorders (ASD), and emerging evidence suggests vitamin D is involved in brain development. Most prior studies of ASD examined vitamin D levels in children already diagnosed, but a few examined levels during perinatal development, the more likely susceptibility period. Therefore, we examined newborn vitamin D levels in a case-control study conducted among births in 2000-2003 in southern California. Children with ASD (N = 563) or intellectual disability (ID) (N = 190) were identified from the Department of Developmental Services and compared to population controls (N = 436) identified from birth certificates. 25-hydroxyvitamin D (25(OH)D) was measured in archived newborn dried blood spots by a sensitive assay and corrected to sera equivalents. We categorized 25(OH) D levels as deficient (<50 nmol/L), insufficient (50-74 nmol/L), and sufficient (≥75 nmol/L), and also examined continuous levels, using logistic regression. The adjusted odds ratios (AOR) and 95% confidence intervals for ASD were 0.96 (0.64-1.4) for 25(OH)D deficiency (14% of newborns) and 1.2 (0.86-1.6) for insufficiency (26% of newborns). The AORs for continuous 25(OH)D (per 25 nmol/L) were 1.0 (0.91-1.09) for ASD and 1.14 (1.0-1.30) for ID. Thus, in this relatively large study of measured newborn vitamin D levels, our results do not support the hypothesis of lower 25(OH)D being associated with higher risk of ASD (or ID), although we observed suggestion of interactions with sex and race/ethnicity. 25(OH)D levels were relatively high (median 84 nmol/L in controls), so results may differ in populations with higher prevalence of low vitamin D levels. Autism Res 2019, 12: 989-998. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We studied whether vitamin D levels measured at birth were related to whether a child later developed autism (or low IQ). Our results did not show that children with autism, or low IQ, overall had lower vitamin D levels at birth than children without autism. Vitamin D levels were fairly high, on average, in these children born in Southern California.

Life-course neighbourhood opportunity and racial-ethnic disparities in risk of preterm birth

BACKGROUND

Neighbourhood opportunity, measured by poverty, income and deprivation, has been associated with preterm birth, however little is known about the contribution of early-life and life-course neighbourhood opportunity to preterm birth risk and racial-ethnic disparities. We examined maternal early-life and adult neighbourhood opportunity in relation to risk of preterm birth and racial-ethnic disparities in a population-based cohort of women under age 30.

METHODS

We linked census tract poverty data to 2 generations of California births from 1982-2011 for 403 315 white, black, or Latina mothers-infant pairs. We estimated the risk of preterm birth, and risk difference (RD) comparing low opportunity (≥20% poverty) in early life or adulthood to high opportunity using targeted maximum likelihood estimation.

RESULTS

At each time point, low opportunity was related to increased preterm birth risk compared to higher opportunity neighbourhoods for white, black and Latina mothers (RDs 0.3-0.7%). Compared to high opportunity at both time points, risk differences were generally highest for sustained low opportunity (RD 1.5, 1.3, and 0.7% for white, black and Latina mothers, respectively); risk was elevated with downward mobility (RD 0.7, 1.3, and 0.4% for white, black and Latina mothers, respectively), and with upward mobility only among black mothers (RD 1.2%). The black-white preterm birth disparity was reduced by 22% under high life-course opportunity.

CONCLUSIONS

Early-life and sustained exposure to residential poverty is related to increased PTB risk, particularly among black women, and may partially explain persistent black-white disparities.

Cross-genetic determination of maternal and neonatal immune mediators during pregnancy

BACKGROUND

The immune system plays a fundamental role in development during pregnancy and early life. Alterations in circulating maternal and neonatal immune mediators have been associated with pregnancy complications as well as susceptibility to autoimmune and neurodevelopmental conditions in later life. Evidence suggests that the immune system in adults not only responds to environmental stimulation but is also under strong genetic control.

METHODS

This is the first genetic study of > 700 mother-infant pairs to analyse the circulating levels of 22 maternal mid-gestational serum-derived and 42 neonatal bloodspot-derived immune mediators (cytokines/chemokines) in the context of maternal and fetal genotype. We first estimated the maternal and fetal genome-wide SNP-based heritability (h2g) for each immune molecule and then performed genome-wide association studies (GWAS) to identify specific loci contributing to individual immune mediators. Finally, we assessed the relationship between genetic immune determinants and ASD outcome.

RESULTS

We show maternal and neonatal cytokines/chemokines displaying genetic regulation using independent methodologies. We demonstrate that novel fetal loci for immune function independently affect the physiological levels of maternal immune mediators and vice versa. The cross-associated loci are in distinct genomic regions compared with individual-specific immune mediator loci. Finally, we observed an interaction between increased IL-8 levels at birth, autism spectrum disorder (ASD) status, and a specific maternal genotype.

CONCLUSIONS

Our results suggest that maternal and fetal genetic variation influences the immune system during pregnancy and at birth via distinct mechanisms and that a better understanding of immune factor determinants in early development may shed light on risk factors for developmental disorders.

Prenatal Maternal Serum Concentrations of Per- and Polyfluoroalkyl Substances in Association with Autism Spectrum Disorder and Intellectual Disability

BACKGROUND

Emerging work has examined neurodevelopmental outcomes following prenatal exposure to per- and polyfluoroalkyl substances (PFAS), but few studies have assessed associations with autism spectrum disorder (ASD).

OBJECTIVES

Our objective was to estimate associations of maternal prenatal PFAS concentrations with ASD and intellectual disability (ID) in children.

METHODS

Participants were from a population-based nested case-control study of children born from 2000 to 2003 in southern California, including children diagnosed with ASD (n=553), ID without autism (n=189), and general population (GP) controls (n=433). Concentrations of eight PFAS from stored maternal sera collected at 15-19 wk gestational age were quantified and compared among study groups. We used logistic regression to obtain adjusted odds ratios for the association between prenatal PFAS concentrations (parameterized continuously and as quartiles) and ASD versus GP controls, and separately for ID versus GP controls.

RESULTS

Geometric mean concentrations of most PFAS were lower in ASD and ID groups relative to GP controls. ASD was not significantly associated with prenatal concentrations of most PFAS, though significant inverse associations were found for perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) [adjusted ORs for the highest vs. lowest quartiles 0.62 (95% CI: 0.41, 0.93) and 0.64 (95% CI: 0.43, 0.97), respectively]. Results for ID were similar.

CONCLUSIONS

Results from this large case-control study with prospectively collected prenatal measurements do not support the hypothesis that prenatal exposure to PFAS is positively associated with ASD or ID. https://doi.org/10.1289/EHP1830.

Maternal perchlorate exposure in pregnancy and altered birth outcomes

BACKGROUND

At high medicinal doses perchlorate is known to decrease the production of thyroid hormone, a critical factor for fetal development. In a large and uniquely exposed cohort of pregnant women, we recently identified associations between environmental perchlorate exposures and decreased maternal thyroid hormone during pregnancy. Here, we investigate whether perchlorate might be associated with birthweight or preterm birth in the offspring of these women.

METHODS

Maternal urinary perchlorate, serum thyroid hormone concentrations, birthweight, gestational age, and urinary nitrate, thiocyanate, and iodide were collected in 1957 mother-infant pairs from San Diego County during 2000-2003, a period when the county's water supply was contaminated with perchlorate. Associations between perchlorate exposure and birth outcomes were examined using linear and logistic regression analyses adjusted for maternal age, weight, race/ethnicity, and other factors.

RESULTS

Perchlorate was not associated with birth outcomes in the overall population. However, in analyses confined to male infants, log₁₀ maternal perchlorate concentrations were associated with increasing birthweight (β=143.1gm, p=0.01), especially among preterm births (β=829.1g, p<0.001). Perchlorate was associated with male preterm births ≥2500g (odds ratio=3.03, 95% confidence interval=1.09-8.40, p-trend=0.03). Similar associations were not seen in females.

CONCLUSIONS

This is the first study to identify associations between perchlorate and increasing birthweight. Further research is needed to explore the differences we identified related to infant sex, preterm birth, and other factors. Given that perchlorate exposure is ubiquitous, and that long-term impacts can follow altered birth outcomes, future research on perchlorate could have widespread public health importance.

Prenatal Serum Concentrations of Brominated Flame Retardants and Autism Spectrum Disorder and Intellectual Disability in the Early Markers of Autism Study: A Population-Based Case-Control Study in California

BACKGROUND

Prior studies suggest neurodevelopmental impacts of polybrominated diphenyl ethers (PBDEs), but few have examined diagnosed developmental disorders.

OBJECTIVES

Our aim was to determine whether prenatal exposure to brominated flame retardants (BFRs) is associated with autism spectrum disorder (ASD) or intellectual disability without autism (ID).

METHODS

We conducted a population-based case-control study including children with ASD (n=545) and ID (n=181) identified from the California Department of Developmental Services and general population (GP) controls (n=418) from state birth certificates. ASD cases were matched to controls by sex, birth month, and birth year. Concentrations of 10 BFRs were measured in maternal second trimester serum samples stored from routine screening. Logistic regression was used to calculate crude and adjusted odds ratios (AOR) for associations with ASD, and separately for ID, compared with GP controls, by quartiles of analyte concentrations in primary analyses.

RESULTS

Geometric mean concentrations of five of the six congeners with ≥55% of samples above the limit of detection were lower in mothers of children with ASD or ID than in controls. In adjusted analyses, inverse associations with several congeners were found for ASD relative to GP (e.g., quartile 4 vs. 1, BDE-153: AOR=0.56, 95% CI: 0.38, 0.84). When stratified by child sex (including 99 females with ASD, 77 with ID, and 73 with GP), estimates were consistent with overall analyses in boys, but in the opposite direction among girls, particularly for BDE-28 and -47 (AOR=2.58, 95% CI: 0.86, 7.79 and AOR=2.64, 95% CI: 0.97, 7.19, respectively). Similar patterns overall and by sex were observed for ID.

CONCLUSIONS

Contrary to expectation, higher PBDE concentrations were associated with decreased odds of ASD and ID, though not in girls. These findings require confirmation but suggest potential sexual dimorphism in associations with prenatal exposure to BFRs. https://doi.org/10.1289/EHP1079.

Polychlorinated Biphenyl and Organochlorine Pesticide Concentrations in Maternal Mid-Pregnancy Serum Samples: Association with Autism Spectrum Disorder and Intellectual Disability

BACKGROUND

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are neurodevelopmental toxicants, but few studies have examined associations with autism spectrum disorder (ASD).

OBJECTIVES

We aimed to determine whether prenatal exposure to PCBs and OCPs influences offspring risk of ASD and intellectual disability without autism (ID).

METHODS

We conducted a population-based case-control study among Southern California births, including children with ASD (n = 545) meeting Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV-TR) criteria and ID (n = 181), as well as general population (GP) controls (n = 418). Concentrations of 11 PCB congeners and 2 OCPs measured in banked second-trimester serum samples were compared between the diagnostic groups. Logistic regression was used to calculate crude and adjusted odds ratios (AOR) for associations with ASD, and separately for ID, compared with GP controls, by quartiles of analyte concentrations in primary analyses.

RESULTS

Geometric mean levels of several PCB congeners were higher in the ASD group than in the ID and GP groups. ASD risk was elevated for a number of PCB congeners, particularly for the highest vs. lowest quartile of PCB138/158 (AOR = 1.79; 95% CI: 1.10, 2.71) and PCB153 (AOR = 1.82; 95% CI: 1.10, 3.02), and for highest deciles of other congeners in secondary analyses. PCB138/158 was also associated with increased ID (AOR = 2.41; 95% CI: 1.18, 4.91), though no trend was suggested. OCPs were not associated with increased risk of ASD in primary analyses, whereas nonmonotonic increases in risk of ID were found with p,p´-DDE.

CONCLUSIONS

Our results suggest higher levels of some organochlorine compounds during pregnancy are associated with ASD and ID. Citation: Lyall K, Croen LA, Sjödin A, Yoshida CK, Zerbo O, Kharrazi M, Windham GC. 2017. Polychlorinated biphenyl and organochlorine pesticide concentrations in maternal mid-pregnancy serum samples: association with autism spectrum disorder and intellectual disability. Environ Health Perspect 125:474-480; http://dx.doi.org/10.1289/EHP277.

Autism Spectrum Disorder Risk in Relation to Maternal Mid-Pregnancy Serum Hormone and Protein Markers from Prenatal Screening in California

We examined prenatal screening markers and offspring autism spectrum disorder (ASD) using California statewide data on singleton births in 1996 and 2002. Second trimester levels of unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and maternal serum alpha-fetoprotein (MSAFP) were compared between mothers of children with ASD (n = 2586) and of non-cases (n = 600,103). Adjusted odds ratios (AOR) were calculated by logistic regression. Lower uE3 (AOR for < 10th percentile vs. 25th-74th percentiles = 1.21, 95 % CI 1.06-1.37), and higher MSAFP (AOR = 1.21, 95 % CI 1.07-1.37 for > 90th percentile) were significantly associated with ASD. A U-shaped relationship was seen for hCG (AOR = 1.16, 95 % CI 1.02-1.32 for < 10th percentile; AOR = 1.19, 95 % CI 1.05-1.36 for > 90th percentile). Our results further support prenatal hormone involvement in ASD risk.

Racial-ethnic differences in midtrimester maternal serum levels of angiogenic and antiangiogenic factors

BACKGROUND

Little is known about racial-ethnic differences in the distribution of maternal serum levels of angiogenic and antiangiogenic factors and their associations with early-onset preeclampsia.

OBJECTIVE

We sought to investigate the distribution of midtrimester maternal serum levels of placental growth factor, soluble endoglin, and soluble vascular endothelial growth factor receptor 1 and their associations with early-onset preeclampsia in whites, Hispanics, and blacks.

STUDY DESIGN

A population-based nested case-control design was used to identify cases and controls of white, Hispanic, and black origin from a 2000 through 2007 live-birth cohort in 5 southern California counties. Cases included 197 women (90 whites, 67 Hispanics, and 40 blacks) with early-onset preeclampsia defined as hypertension and proteinuria with onset <32 weeks according to hospital records. Controls included a random sample of 2363 women without early-onset preeclampsia. Maternal serum specimens collected at 15-20 weeks' gestation as part of routine prenatal screening were tested for placental growth factor, soluble endoglin, and soluble vascular endothelial growth factor receptor 1. Serum levels of the 3 factors were log-normally distributed. Adjusted natural logarithmic means were compared between cases and controls and between racial-ethnic groups. Odds ratios and 95% confidence intervals derived from logistic regression models were calculated to measure the magnitude of the associations.

RESULTS

Cases showed lower adjusted logarithmic means of placental growth factor but higher adjusted logarithmic means of soluble endoglin than controls across all 3 groups (P < .05). Cases also had higher adjusted means of soluble vascular endothelial growth factor receptor 1 than controls in whites (7.75 vs 7.52 log pg/mL, P < .05) and Hispanics (7.73 vs 7.40 log pg/mL, P < .05) but not in blacks (7.85 vs 7.69 log pg/mL, P = .47). Blacks were found to have higher levels of placental growth factor in both cases and controls when compared to whites and Hispanics (adjusted means: 4.69 and 5.20 log pg/mL in blacks, 4.08 and 4.78 log pg/mL in whites, and 3.89 and 4.70 log pg/mL in Hispanics, respectively, P < .05). Hispanic cases had the highest adjusted mean of soluble endoglin compared to white and black cases (9.24, 9.05, and 8.93 log pg/mL, respectively, P < .05). The weakest association of early-onset preeclampsia with placental growth factor and soluble endoglin was observed in blacks. The adjusted odds ratio per log pg/mL increase of the 2 analytes were 0.219 (95% confidence interval, 0.124-0.385) and 5.02 (95% confidence interval, 2.56-9.86) in blacks in comparison to 0.048 (95% confidence interval, 0.026-0.088) and 36.87 (95% confidence interval, 17.00-79.96) in whites (P < .05) and 0.028 (95% confidence interval, 0.013-0.060) and 86.68 (95% confidence interval, 31.46-238.81) in Hispanics (P < .05), respectively. As for soluble vascular endothelial growth factor receptor 1, the association was not significantly different among the racial-ethnic groups.

CONCLUSION

Racial-ethnic differences were observed in the distribution of midtrimester maternal levels of placental growth factor and soluble endoglin and in the associations with early-onset preeclampsia. These differences should be considered in future studies to improve etiologic and prognostic understanding of early-onset preeclampsia.

Phenotypes of California CF Newborn Screen-Positive Children with CFTR 5T Allele by TG Repeat Length

BACKGROUND

At the cystic fibrosis transmembrane conductance regulator (CFTR) gene (IVS8)-(TG)m(T)n locus, a lower number of thymidines (legacy names 9T vs. 7T vs. 5T) and a higher number of (TG) repeats (TG-11 vs. 12 vs. 13) are associated with decreasing translation of functional CFTR protein in vitro.

METHODS

Retrospective cohort study comparing phenotypes of California CF newborn screen-positive children (followed 2-8 years) who had two CF-causing mutations (diagnosed as CF) with those who had one mutation from a panel of 40 CF-causing mutations (CF40mut) and one (IVS8)-(TG)11, 12, or 13-5T mutation detected by sequencing (diagnosed as CFTR-related metabolic syndrome [cRMS]).

RESULTS

The study included 428 children, of which 234 had two CF-causing mutations, and were used to compare with the other 194 children with one CF-causing mutation and one isolated 5T allele [CF40mut/(TG)13-5T = 21, CF40mut/(TG)12-5T = 85, and CF40mut/(TG)11-5T = 88]. Among children with CF40mut/(TG)13-5T, 38% were diagnosed with CF by 8 years, based on sweat chloride results and clinical presentation. Six percent of those with CF40mut/(TG)12-5T, and none with CF40mut/(TG)11-5T, reached diagnostic criteria.

CONCLUSIONS

CFTR (IVS8)-(TG)m-5T allele (TG) tract length determination provides valuable information in predicting the risk of developing a CF phenotype. Of the three types of 5T alleles evaluated, screen-positive children with genotype CF40mut/(TG)13-5T progressed from CRMS to CF at a high rate, while there was little evidence of clinical disease in those with CF40mut/(TG)11-5T. Additional data from longer follow-up intervals are needed to fully understand the natural history of individuals with a CF40mut/(TG)m-5T genotype.

Thyroid Hormones and Moderate Exposure to Perchlorate during Pregnancy in Women in Southern California

BACKGROUND

Findings from national surveys suggest that everyone in the United States is exposed to perchlorate. At high doses, perchlorate, thiocyanate, and nitrate inhibit iodide uptake into the thyroid and decrease thyroid hormone production. Small changes in thyroid hormones during pregnancy, including changes within normal reference ranges, have been linked to cognitive function declines in the offspring.

OBJECTIVES

We evaluated the potential effects of low environmental exposures to perchlorate on thyroid function.

METHODS

Serum thyroid hormones and anti-thyroid antibodies and urinary perchlorate, thiocyanate, nitrate, and iodide concentrations were measured in 1,880 pregnant women from San Diego County, California, during 2000-2003, a period when much of the area's water supply was contaminated from an industrial plant with perchlorate at levels near the 2007 California regulatory standard of 6 μg/L. Linear regression was used to evaluate associations between urinary perchlorate and serum thyroid hormone concentrations in models adjusted for urinary creatinine and thiocyanate, maternal age and education, ethnicity, and gestational age at serum collection.

RESULTS

The median urinary perchlorate concentration was 6.5 μg/L, about two times higher than in the general U.S.

POPULATION

Adjusted associations were identified between increasing log10 perchlorate and decreasing total thyroxine (T4) [regression coefficient (β) = -0.70; 95% CI: -1.06, -0.34], decreasing free thyroxine (fT4) (β = -0.053; 95% CI: -0.092, -0.013), and increasing log10 thyroid-stimulating hormone (β = 0.071; 95% CI: 0.008, 0.133).

CONCLUSIONS

These results suggest that environmental perchlorate exposures may affect thyroid hormone production during pregnancy. This could have implications for public health given widespread perchlorate exposure and the importance of thyroid hormone in fetal neurodevelopment.

CITATION

Steinmaus C, Pearl M, Kharrazi M, Blount BC, Miller MD, Pearce EN, Valentin-Blasini L, DeLorenze G, Hoofnagle AN, Liaw J. 2016. Thyroid hormones and moderate exposure to perchlorate during pregnancy in women in Southern California. Environ Health Perspect 124:861-867; http://dx.doi.org/10.1289/ehp.1409614.

Benign and Deleterious Cystic Fibrosis Transmembrane Conductance Regulator Mutations Identified by Sequencing in Positive Cystic Fibrosis Newborn Screen Children from California

Background

Of the 2007 Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutations, 202 have been assigned disease liability. California’s racially diverse population, along with CFTR sequencing as part of newborn screening model, provides the opportunity to examine the phenotypes of children with uncategorized mutations to help inform disease liability and penetrance.

Methods

We conducted a retrospective cohort study based on children screened from 2007 to 2011 and followed for two to six years. Newborns that screened positive were divided into three genotype groups: those with two CF-causing mutations (CF-C); those with one mutation of varying clinic consequence (VCC); and those with one mutation of unknown disease liability (Unknown). Sweat chloride tests, pancreatic sufficiency status, and Pseudomonas aeruginosa colonization were compared.

Results

Children with two CF-causing mutations had a classical CF phenotype, while 5% of VCC (4/78) and 11% of Unknown (27/244) met diagnostic criteria of CF. Children carrying Unknown mutations 2215insG with D836Y, and T1036N had early and classical CF phenotype, while others carrying 1525-42G>A, L320V, L967S, R170H, and 296+28A>G had a benign clinical presentation, suggesting that these are non-CF causing.

Conclusions

While most infants with VCC and Unknown CFTR mutations do not meet diagnostic criteria for CF, a small proportion do. These findings highlight the range of genotypes and phenotypes in the first few years of life following CF newborn screening when CFTR sequencing is performed.

Prenatal and Newborn Immunoglobulin Levels from Mother-Child Pairs and Risk of Autism Spectrum Disorders

Background: An etiological role for immune factors operating during early brain development in children with autism spectrum disorders (ASD) has not yet been established. A major obstacle has been the lack of early biologic specimens that can be linked to later diagnosis. In a prior study, we found lower risk of ASD associated with higher levels of maternally-derived total IgG and Toxoplasmosis gondii (Toxo) IgG in newborn blood spot specimens from children later diagnosed with ASD compared to population controls.

Methods: We obtained maternal mid-gestational serum specimens and newborn screening blood spots from the California Genetics Disease Screening Program (GDSP) for linked mother-baby pairs for 84 children with ASD and 49 children with developmental delay but not ASD (DD) identified from California Department of Developmental Services records and for 159 population controls sampled from birth certificates.Immunoglobulin levels in maternal and newborn specimens were measured by solid phase immunoassays and analyzed in logistic regression models for total IgG, total IgM, and Toxo IgG, and, for maternal specimens only, Toxo IgM. Correlations between maternal and newborn ranked values were evaluated.

Results: In both maternal and newborn specimens, we found significantly lower risk of ASD associated with higher levels of Toxo IgG. In addition, point estimates for all comparisons were < 1.0 suggesting an overall pattern of lower immunoglobulin levels associated with higher ASD risk but most did not reach statistical significance. We did not find differences in maternal or newborn specimens comparing children with DD to controls.

Discussion: These results are consistent with evidence from our prior study and other published reports indicating that immune factors during early neurodevelopment may be etiologically relevant to ASD. Lowered immunoglobulin levels may represent suboptimal function of the maternal immune system or reduced maternal exposure to common infectious agents.

Conclusion: Patterns seen in these selected immunoglobulins may provide clues to mechanisms of early abnormalities in neurodevelopment contributing to ASD. We recommend further study of immunoglobulin profiles in larger samples of linked mother-baby pairs to evaluate possible etiologic relevance.

Next-Generation Molecular Testing of Newborn Dried Blood Spots for Cystic Fibrosis

Newborn screening for cystic fibrosis enables early detection and management of this debilitating genetic disease. Implementing comprehensive CFTR analysis using Sanger sequencing as a component of confirmatory testing of all screen-positive newborns has remained impractical due to relatively lengthy turnaround times and high cost. Here, we describe CFseq, a highly sensitive, specific, rapid (<3 days), and cost-effective assay for comprehensive CFTR gene analysis from dried blood spots, the common newborn screening specimen. The unique design of CFseq integrates optimized dried blood spot sample processing, a novel multiplex amplification method from as little as 1 ng of genomic DNA, and multiplex next-generation sequencing of 96 samples in a single run to detect all relevant CFTR mutation types. Sequence data analysis utilizes publicly available software supplemented by an expert-curated compendium of >2000 CFTR variants. Validation studies across 190 dried blood spots demonstrated 100% sensitivity and a positive predictive value of 100% for single-nucleotide variants and insertions and deletions and complete concordance across the polymorphic poly-TG and consecutive poly-T tracts. Additionally, we accurately detected both a known exon 2,3 deletion and a previously undetected exon 22,23 deletion. CFseq is thus able to replace all existing CFTR molecular assays with a single robust, definitive assay at significant cost and time savings and could be adapted to high-throughput screening of other inherited conditions.

Newborn Screening for Cystic Fibrosis in California

OBJECTIVES

This article describes the methods used and the program performance results for the first 5 years of newborn screening for cystic fibrosis (CF) in California.

METHODS

From July 16, 2007, to June 30, 2012, a total of 2,573,293 newborns were screened for CF by using a 3-step model: (1) measuring immunoreactive trypsinogen in all dried blood spot specimens; (2) testing 28 to 40 selected cystic fibrosis transmembrane conductance regulator (CFTR) mutations in specimens with immunoreactive trypsinogen values ≥62 ng/mL (top 1.6%); and (3) performing DNA sequencing on specimens found to have only 1 mutation in step 2. Infants with ≥2 mutations/variants were referred to CF care centers for diagnostic evaluation and follow-up. Infants with 1 mutation were considered carriers and their parents offered telephone genetic counseling.

RESULTS

Overall, 345 CF cases, 533 CFTR-related metabolic syndrome cases, and 1617 carriers were detected; 28 cases of CF were missed. Of the 345 CF cases, 20 (5.8%) infants were initially assessed as having CFTR-related metabolic syndrome, and their CF diagnosis occurred after age 6 months (median follow-up: 4.5 years). Program sensitivity was 92%, and the positive predictive value was 34%. CF prevalence was 1 in 6899 births. A total of 303 CFTR mutations were identified, including 78 novel variants. The median age at referral to a CF care center was 34 days (18 and 37 days for step 2 and 3 screening test-positive infants, respectively).

CONCLUSIONS

The 3-step model had high detection and low false-positive levels in this diverse population.

Prenatal and neonatal thyroid stimulating hormone levels and autism spectrum disorders

Thyroid hormones are critical for normal brain development. This study examined autism spectrum disorders (ASD) and thyroid stimulating hormone (TSH) levels measured in mid-pregnancy maternal serum and infant blood after birth. Three groups of children born in Orange County, CA in 2000-2001 were identified: ASD (n = 78), developmental delay (n = 45), and general population controls (GP) (n = 149). Samples were retrieved from prenatal and newborn screening specimen archives. Adjusted logistic regression models showed inverse associations between ASD and log transformed TSH levels in maternal serum samples (ASD vs. GP: OR [95 % CI] 0.33 [0.12-0.91], Early Onset ASD vs. GP: 0.31 [0.10-0.98]). Results for thyroid levels in newborn blood samples were similar though not significant (ASD vs. GP: 0.61 [0.18-2.04]).

Increased female autosomal burden of rare copy number variants in human populations and in autism families

Autosomal genetic variation is presumed equivalent in males and females and makes a major contribution to disease risk. We set out to identify whether maternal copy number variants (CNVs) contribute to autism spectrum disorders (ASDs). Surprisingly, we observed a higher autosomal burden of large, rare CNVs in females in the population, reflected in, but not unique to, ASD families. Meta-analysis across control data sets confirms female excess in CNV number (P=2.1 × 10(-5)) and gene content (P=4.1 × 10(-3)). We additionally observed CNV enrichment in ASD mothers compared with control mothers (P=0.03). We speculate that tolerance for CNV burden contributes to decreased female fetal loss in the population and that ASD-specific maternal CNV burden may contribute to high sibling recurrence. These data emphasize the need for study of familial CNV risk factors in ASDs and the requirement of sex-matched comparisons.

Prenatal and neonatal peripheral blood mercury levels and autism spectrum disorders

BACKGROUND

Prenatal and early-life exposures to mercury have been hypothesized to be associated with increased risk of autism spectrum disorders (ASDs).

OBJECTIVES

This study investigated the association between ASDs and levels of total mercury measured in maternal serum from mid-pregnancy and infant blood shortly after birth.

METHODS

The study sample was drawn from the Early Markers for Autism (EMA) Study. Three groups of children who were born in Orange County, CA in 2000-2001 were identified: children with ASD (n=84), children with intellectual disability or developmental delay (DD) (n=49), and general population controls (GP) (n=159). Maternal serum specimens and newborn bloodspots were retrieved from the California Department of Public Health prenatal and newborn screening specimen archives. Blood mercury levels were measured in maternal serum samples using mass spectrometer and in infant bloodspots with a 213 nm laser.

RESULTS

Maternal serum and infant blood mercury levels were significantly correlated among all study groups (all correlations >0.38, p<0.01). Adjusted logistic regression models showed no significant associations between ASD and log transformed mercury levels in maternal serum samples (ASD vs. GP: OR [95% CI]=0.96 [0.49-1.90]; ASD vs. DD: OR [95% CI]=2.56 [0.89-7.39]). Results for mercury levels in newborn blood samples were similar (ASD vs. GP: OR [95% CI]=1.18 [0.71-1.95]; ASD vs. DD: OR [95% CI]=1.96 [0.75-5.14]).

CONCLUSIONS

Results indicate that levels of total mercury in serum collected from mothers during mid-pregnancy and from newborn bloodspots were not significantly associated with risk of ASD, though additional studies with greater sample size and covariate measurement are needed.

Precursor-to-product ratios reflect biochemical phenotype in congenital adrenal hyperplasia

Precursor-to-product ratios in steroid hormone metabolism may accurately reflect enzymatic activity and production of metabolites relative to their disappearance. The purpose of this study was to explore the use of direct precursor-to-product steroid ratios to discriminate between infants with congenital adrenal hyperplasia (CAH) due to 21- α -hydroxylase deficiency and infants with no disorder, thus characterizing the biochemical phenotype in CAH. Deidentified dried blood spot samples from confirmed CAH cases identified by newborn screen (CAH-positive, N = 8) and from cases with no disorder (CAH-negative, N = 10) were obtained from the California State Newborn Screening Program. Samples (∼6.25 mm circular spots) underwent methanol and water extraction (9:1 ratio). Deuterated steroids served as isotope internal standards. 17-α-hydroxyprogesterone (17-OHP), 11-deoxycortisol (S), androstenedione (A4) and cortisol (F) concentrations were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the 17-OHP/S, 17-OHP/A4, and S/F ratios were calculated. The mean 17-OHP and A4 concentrations in samples from CAH cases were significantly increased when compared to cases with no disorder (p = 0.003 for both). 17-OHP/S and 17-OHP/A4 ratios were also significantly elevated in CAH cases (p = 0.007 and p < 0.001, respectively). In contrast, S and F concentrations and the S/F ratio were similar between the two groups. In CAH, the elevated 17-OHP/S ratio is a biomarker of diminished 21-α-hydroxylase activity, and the elevated 17-OHP/A4 ratio is a biomarker of adrenal androgen excess via increased 17,20-lyase activity. The similar S/F ratio indicates that the rate of production via 11-β-hydroxylase and disappearance of F is maintained in CAH.

Validation of obstetric estimate using early ultrasound: 2007 California birth certificates

BACKGROUND

Obstetric estimate (OE) of gestational age, recently added to the standard US birth certificate, has not been validated. Using early ultrasound-based gestational age (prior to 20 weeks gestation) as the criterion standard, we estimated the prevalence of preterm delivery and the sensitivity and positive predictive value (PPV) of gestational age estimates based on OE.

METHODS

We analyzed 165 148 singleton livebirth records (38% of California livebirths during the study period) with linked early ultrasound information from a statewide California prenatal screening programme. OE of gestational age estimates was obtained from birth certificates.

RESULTS

Prevalence of preterm delivery (<37 weeks gestation) was higher based on early ultrasound (8.1%) compared with preterm delivery based on OE (7.1%). Sensitivity for preterm birth when using OE for gestational age was 74.9% (95% confidence interval [CI] [74.1, 75.6]), and PPV was 85.1% (95% CI [84.4, 85.7]). Incongruence, defined as a ≥ 14-day difference between early-ultrasound-derived gestational age and OE, was 3.4%.

CONCLUSIONS

OE reported on the birth certificate may underestimate the prevalence of preterm delivery, particularly among women of non-Hispanic non-white race and ethnicity and women with lower educational attainment, public insurance at time of delivery, and missing prepregnancy BMI. Additional validation studies in other samples of births are needed.

Levels of cotinine in dried blood specimens from newborns as a biomarker of maternal smoking close to the time of delivery

The precise quantitation of smoking during pregnancy is difficult in retrospective studies. Routinely collected blood specimens from newborns, stored as dried blood spots, may provide a low-cost method to objectively measure maternal smoking close to the time of delivery. This article compares cotinine levels in dried blood spots to those in umbilical cord blood to assess cotinine in dried blood spots as a biomarker of maternal smoking close to the time of delivery. The California Genetic Disease Screening Program provided dried blood spots from 428 newborns delivered in 2001-2003 with known umbilical cord blood cotinine levels. Cotinine in dried blood spots was measured in 6.35--mm punches by using liquid chromatography--tandem mass spectrometry (quantitation limit, 3.1 ng/mL). Repeated measures of cotinine in dried blood spots were highly correlated (R(2) = 0.99, P < 0.001) among 100 dried blood spots with cotinine quantitated in 2 separate punches. Linear regression revealed that cotinine levels in dried blood spots were slightly lower than those in umbilical cord blood and predicted umbilical cord blood cotinine levels well (β = 0.95, R(2) = 0.80, and P < 0.001 for both cotinine levels in log10 scale). When defining active smoking as a cotinine level of 10 ng/mL or more and using umbilical cord blood cotinine as the criterion standard, we found that measurements of cotinine in dried blood spots had high sensitivity (92.3%) and specificity (99.7%) in the prediction of maternal active smoking. Cotinine levels in dried blood spots are an accurate biomarker of maternal smoking close to the time of delivery.

A genome-wide survey of transgenerational genetic effects in autism

Effects of parental genotype or parent-offspring genetic interaction are well established in model organisms for a variety of traits. However, these transgenerational genetic models are rarely studied in humans. We have utilized an autism case-control study with 735 mother-child pairs to perform genome-wide screening for maternal genetic effects and maternal-offspring genetic interaction. We used simple models of single locus parent-child interaction and identified suggestive results (P<10⁻⁴) that cannot be explained by main effects, but no genome-wide significant signals. Some of these maternal and maternal-child associations were in or adjacent to autism candidate genes including: PCDH9, FOXP1, GABRB3, NRXN1, RELN, MACROD2, FHIT, RORA, CNTN4, CNTNAP2, FAM135B, LAMA1, NFIA, NLGN4X, RAPGEF4, and SDK1. We attempted validation of potential autism association under maternal-specific models using maternal-paternal comparison in family-based GWAS datasets. Our results suggest that further study of parental genetic effects and parent-child interaction in autism is warranted.

Natural selection in utero induced by mass layoffs: the hCG evidence

Evolutionary theory, when coupled with research from epidemiology, demography, and population endocrinology, suggests that contracting economies affect the fitness and health of human populations via natural selection in utero. We know, for example, that fetal death increases more among males than females when the economy unexpectedly contracts; that unexpected economic contraction predicts low secondary sex ratios; and that males from low sex ratio birth cohorts live, on average, longer than those from high sex ratio cohorts. We also know that low levels of human chorionic gonadotropin (i.e., hCG) measured in the serum of pregnant women predict fetal death. We do not, however, know whether male survivors of conception cohorts subjected to contracting economies exhibit, as theory predicts, higher hCG than those from other cohorts. We show, in 71 monthly conception cohorts including nearly two million California births, that they do. We thereby add to the literature suggesting that the economy, a phenomenon over which we collectively exercise at least some control, affects population health. Our findings imply that the effect arises via natural selection - a mechanism we largely ignore when attempting to explain, or alter, how collective choice affects our biology.

A test of maternal human chorionic gonadotropin during pregnancy as an adaptive filter of human gestations

The risk of abnormalities and morbidity among live births increases with advanced maternal age. Explanations for this elevated morbidity invoke several maternal mechanisms. The relaxed filter stringency (RFS) hypothesis asserts that mothers, nearing the end of their reproductive lifespan, reduce the stringency of a screen of offspring quality in utero based on life-history traits of parity and interbirth interval (IBI). A separate line of research implicates human chorionic gonadotropin (hCG) during pregnancy as a signal of offspring quality. We test the RFS hypothesis directly by examining whether the difference in gestational hCG across consecutive live births varies positively with the mother's number of previous live births but inversely with her most recent IBI. We applied multivariable regression methods to a unique dataset of gestational hCG for over 500 000 live births from 2002 to 2007. The difference in gestational hCG across mothers' consecutive live births varies positively with both mothers' parity and IBI. These associations remain similar among older mothers (35+ years). Findings support the RFS hypothesis for the parity expectation but not for the IBI expectation. Further evidence for the RFS hypothesis among contemporary human gestations would have to invoke screening mechanisms other than hCG.

Hormonal evidence supports the theory of selection in utero

OBJECTIVES

Antagonists in the debate over whether the maternal stress response during pregnancy damages or culls fetuses have invoked the theory of selection in utero to support opposing positions. We describe how these opposing arguments arise from the same theory and offer a novel test to discriminate between them. Our test, rooted in reports from population endocrinology that human chorionic gonadotropin (hCG) signals fetal fitness, contributes not only to the debate over the fetal origins of illness, but also to the more basic literature concerned with whether and how natural selection in utero affects contemporary human populations.

METHODS

We linked maternal serum hCG measurements from prenatal screening tests with data from the California Department of Public Health birth registry for the years 2001-2007. We used time series analysis to test the association between the number of live-born male singletons and median hCG concentration among males in monthly gestational cohorts.

RESULTS

Among the 1.56 million gestations in our analysis, we find that median hCG levels among male survivors of monthly conception cohorts rise as the number of male survivors falls.

RESULTS

Elevated median hCG among relatively small male birth cohorts supports the theory of selection in utero and suggests that the maternal stress response culls cohorts in gestation by raising the fitness criterion for survival to birth.

California Very Preterm Birth Study: design and characteristics of the population- and biospecimen bank-based nested case-control study

Very preterm birth (VPTB) is a leading cause of infant mortality, morbidity and racial disparity in the US. The underlying causes of VPTB are multiple and poorly understood. The California Very Preterm Birth Study was conducted to discover maternal and infant genetic and environmental factors associated with VPTB. This paper describes the study design, population, data and specimen collection, laboratory methods and characteristics of the study population. Using a large, population-based cohort created through record linkage of livebirths delivered from 2000 to 2007 in five counties of southern California, and existing data and banked specimens from statewide prenatal and newborn screening, 1100 VPTB cases and 796 control mother-infant pairs were selected for study (385/200 White, 385/253 Hispanic and 330/343 Black cases/controls, respectively). Medical record abstraction of cases was conducted at over 50 hospitals to identify spontaneous VPTB, improve accuracy of gestational age, obtain relevant clinical data and exclude cases that did not meet eligibility criteria. VPTB was defined as birth at <32 weeks in Whites and Hispanics and <34 weeks in Blacks. Approximately 55% of all VPTBs were spontaneous and 45% had medical indications or other exclusions. Of the spontaneous VPTBs, approximately 41% were reported to have chorioamnionitis. While the current focus of the California Very Preterm Birth Study is to assess the role of candidate genetic markers on spontaneous VPTB, its design enables the pursuit of other research opportunities to identify social, clinical and biological determinants of different types of VPTB with the ultimate aim of reducing infant mortality, morbidity and racial disparities in these health outcomes in the US and elsewhere.

CFTR mutation analysis and haplotype associations in CF patients

Most newborn screening (NBS) laboratories use second-tier molecular tests for cystic fibrosis (CF) using dried blood spots (DBS). The Centers for Disease Control and Prevention's NBS Quality Assurance Program offers proficiency testing (PT) in DBS for CF transmembrane conductance regulator (CFTR) gene mutation detection. Extensive molecular characterization on 76 CF patients, family members or screen positive newborns was performed for quality assurance. The coding, regulatory regions and portions of all introns were sequenced and large insertions/deletions were characterized as well as two intronic di-nucleotide microsatellites. For CF patient samples, at least two mutations were identified/verified and four specimens contained three likely CF-associated mutations. Thirty-four sequence variations in 152 chromosomes were identified, five of which were not previously reported. Twenty-seven of these variants were used to predict haplotypes from the major haplotype block defined by HapMap data that spans the promoter through intron 19. Chromosomes containing the F508del (p.Phe508del), G542X (p.Gly542X) and N1303K (p.Asn1303Lys) mutations shared a common haplotype subgroup, consistent with a common ancient European founder. Understanding the haplotype background of CF-associated mutations in the U.S. population provides a framework for future phenotype/genotype studies and will assist in determining a likely cis/trans phase of the mutations without need for parent studies.

Increased midgestational IFN-γ, IL-4 and IL-5 in women bearing a child with autism: A case-control study

Background

Immune anomalies have been documented in individuals with autism spectrum disorders (ASDs) and their family members. It is unknown whether the maternal immune profile during pregnancy is associated with the risk of bearing a child with ASD or other neurodevelopmental disorders.

Methods

Using Luminex technology, levels of 17 cytokines and chemokines were measured in banked serum collected from women at 15 to 19 weeks of gestation who gave birth to a child ultimately diagnosed with (1) ASD (n = 84), (2) a developmental delay (DD) but not autism (n = 49) or (3) no known developmental disability (general population (GP); n = 159). ASD and DD risk associated with maternal cytokine and chemokine levels was estimated by using multivariable logistic regression analysis.

Results

Elevated concentrations of IFN-γ, IL-4 and IL-5 in midgestation maternal serum were significantly associated with a 50% increased risk of ASD, regardless of ASD onset type and the presence of intellectual disability. By contrast, elevated concentrations of IL-2, IL-4 and IL-6 were significantly associated with an increased risk of DD without autism.

Conclusion

The profile of elevated serum IFN-γ, IL-4 and IL-5 was more common in women who gave birth to a child subsequently diagnosed with ASD. An alternative profile of increased IL-2, IL-4 and IL-6 was more common for women who gave birth to a child subsequently diagnosed with DD without autism. Further investigation is needed to characterize the relationship between these divergent maternal immunological phenotypes and to evaluate their effect on neurodevelopment.

The association between pre-pregnancy BMI and preterm delivery in a diverse southern California population of working women

Whereas preterm birth has consistently been associated with low maternal pre-pregnancy weight, the relationship with high pre-pregnancy weight has been inconsistent. We quantified the pre-pregnancy BMI-preterm delivery (PTD) relationship using traditional BMI categories (underweight, normal weight, overweight and obese) as well as continuous BMI. Eligible women participated in California's statewide prenatal screening program, worked during pregnancy, and delivered a live singleton birth in Southern California in 2002-2003. The final analytic sample included 354 cases delivering at <37 weeks, as identified by clinical estimate of gestational age from screening records, and 710 term normal-birthweight controls. Multivariable logistic regression models using categorical BMI levels and continuous BMI were compared. In categorical analyses, PTD was significantly associated with pre-pregnancy underweight only. Nonparametric local regression revealed a V-shaped relationship between continuous BMI and PTD, with minimum risk at the high end of normal, around 24 kg/m2. The odds ratio (OR) for PTD associated with low BMI within the normal range (19 kg/m2) was 2.84 (95% CI = 1.61-5.01); ORs for higher BMI in the overweight (29 kg/m2) and obese (34 kg/m2) ranges were 1.42 (95% CI = 1.10-1.84) and 2.01 (95% CI = 1.20-3.39) respectively, relative to 24 kg/m2). BMI categories obscured the preterm delivery risk associated with low-normal, overweight, and obese BMI. We found that higher BMI up to around 24 kg/m2 is increasingly protective of preterm delivery, beyond which a higher body mass index becomes detrimental. Current NHLBI/WHO BMI categories may be inadequate for identifying women at higher risk for PTD.

Use of screening dried blood spots for estimation of prevalence, risk factors, and birth outcomes of congenital cytomegalovirus infection

OBJECTIVES

To determine the birth prevalence of cytomegalovirus (CMV) in a population-based sample of newborns by use of dried blood spots compared with previous studies that used established detection methods, and to evaluate risk factors and birth outcomes for congenital CMV infection.

STUDY DESIGN

A total of 3972 newborn dried blood spots collected for the California Newborn Screening Program were tested for presence of CMV DNA. Demographic and pregnancy data were obtained from linked newborn screening and live-birth records.

RESULTS

CMV prevalence among newborns by maternal race and ethnicity was 0.9% for blacks, 0.8% for Hispanics, 0.6% for whites, and 0.6% for Asians. Among Hispanics (n = 2053), infants who were infected had younger mothers (23 vs 26 years, P = .03), and prevalence was higher for children with no father information provided (2.6% vs 0.6%, P = .03). Overall CMV infection was associated with low birth weight (prevalence ratios [95% CI]: 3.4 [1.4-8.5]) and preterm birth (2.7 [1.4-5.1]). CMV viral loads were inversely related to birth weight and gestational age (both P = .03).

CONCLUSIONS

CMV prevalence measured with dried blood spots was similar to reports using standard viral culture methods. Dried blood spots may be suitable for detection of CMV infection in newborns and warrant further evaluation. Congenital CMV infection may contribute to low birth weight and preterm birth.

Brain-derived neurotrophic factor and autism: maternal and infant peripheral blood levels in the Early Markers for Autism (EMA) Study

To investigate levels of brain-derived neurotrophic factor (BDNF) in mid-pregnancy and neonatal blood specimens as early biologic markers for autism, we conducted a population-based case-control study nested within the cohort of infants born from July 2000 to September 2001 to women who participated in the prenatal screening program in Orange County, CA. Cases (n=84) were all children receiving services for autism at the Regional Center of Orange County. Two comparison groups from the same study population were included: children with mental retardation or developmental delay (n=49) receiving services at the same regional center, and children not receiving services for developmental disabilities, randomly sampled from the California birth certificate files (n=159), and frequency matched to autism cases on sex, birth year, and birth month. BDNF concentrations were measured in archived mid-pregnancy and neonatal blood specimens drawn during routine prenatal and newborn screening using a highly sensitive bead-based assay (Luminex, Biosource Human BDNF Antibody Bead Kit, Invitrogen-Biosource, Carlsbad, CA). The concentration of BDNF in maternal mid-pregnancy and neonatal specimens was similar across all three study groups. These data do not support previous findings of an association between BDNF and autism and suggest that the concentration of BDNF during critical periods of early neurodevelopment is not likely to be a useful biomarker for autism susceptibility.