Assessment of demographic and perinatal predictors of non-response and impact of non-response on measures of association in a population-based case control study: findings from the Georgia Study to Explore Early Development

Prevalence of Developmental, Psychiatric, and Neurologic Conditions in Older Siblings of Children with and without Autism Spectrum Disorder: Study to Explore Early Development

This study evaluated developmental, psychiatric, and neurologic conditions among older siblings of children with and without autism spectrum disorder (ASD) to understand the extent of familial clustering of these diagnoses. Using data from the Study to Explore Early Development, a large multi-site case-control study, the analyses included 2,963 children aged 2-5 years with ASD, other developmental disabilities (DD group), and a population-based control group (POP). Percentages of index children with older siblings with select developmental, psychiatric, and neurologic conditions were estimated and compared across index child study groups using chi-square tests and multivariable modified Poisson regression. In adjusted analyses, children in the ASD group were significantly more likely than children in the POP group to have one or more older siblings with ASD, developmental delay, attention-deficit/hyperactivity disorder, intellectual disability, sensory integration disorder (SID), speech/language delays, or a psychiatric diagnosis (adjusted prevalence ratio [aPR] range: 1.4-3.7). Children in the DD group were significantly more likely than children in the POP group to have an older sibling with most of the aforementioned conditions, except for intellectual disability and psychiatric diagnosis (aPR range: 1.4-2.2). Children in the ASD group were significantly more likely than children in the DD group to have one or more older siblings with ASD, developmental delay, SID, or a psychiatric diagnosis (aPR range: 1.4-1.9). These findings suggest that developmental disorders cluster in families. Increased monitoring and screening for ASD and other DDs may be warranted when an older sibling has a DD diagnosis or symptoms.

Malpresentation and autism spectrum disorder in the study to explore early development

BACKGROUND

An infant's presentation at delivery may be an early indicator of developmental differences. Non-vertex presentation (malpresentation) complicates delivery and often leads to caesarean section, which has been associated with neurodevelopmental delays, including autism spectrum disorder (ASD). However, malpresentation could be an early sign of an existing developmental problem that is also an upstream factor from caesarean delivery. Little research has been done to investigate the association between malpresentation and ASD.

OBJECTIVES

We examine the association between malpresentation at delivery and ASD and whether this association differs by gestational age.

METHODS

We used data from the Study to Explore Early Development (SEED), a multi-site, case-control study of children with ASD compared to population controls. The foetal presentation was determined using medical records, birth records and maternal interviews. We defined malpresentation as a non-vertex presentation at delivery, then further categorised into breech and other malpresentation. We used multivariable logistic regression to estimate the adjusted odds ratio (aOR) for the association between malpresentation and ASD.

RESULTS

We included 4047 SEED participants, 1873 children with ASD and 2174 controls. At delivery, most infants presented vertex (n = 3760, 92.9%). Malpresentation was associated with higher odds of ASD (aOR 1.31, 95% confidence interval [CI] 1.02, 1.68) after adjustment for maternal age, poverty level, hypertensive disorder and smoking. The association was similar for breech and other types of malpresentation (aOR 1.28, 95% CI 0.97, 1.70 and aOR 1.40, 95% CI 0.87, 2.26, respectively) and did not differ markedly by gestational age.

CONCLUSIONS

Malpresentation at delivery was modestly associated with ASD. Early monitoring of the neurodevelopment of children born with malpresentation could identify children with ASD sooner and enhance opportunities to provide support to optimise developmental outcomes.

Prenatal ultrasound use and risk of autism spectrum disorder: Findings from the case-control Study to Explore Early Development

BACKGROUND

Studies evaluating the association between prenatal ultrasounds and autism spectrum disorder (ASD) have largely produced negative results. Concern remains due to the rising identification of children with ASD and ultrasound use.

OBJECTIVE

To evaluate the association between prenatal ultrasound use and ASD.

METHODS

We used data from the Study to Explore Early Development, a multisite case-control study of preschool-aged children with ASD implemented during 2007-2012. We recruited cases from children receiving developmental disability services and randomly selected population controls from birth records. ASD case status was based on in-person standardised assessments. We stratified analyses by pre-existing maternal medical conditions and pregnancy complications associated with increased ultrasound use (ultrasound indications) and used logistic regression to model case status by increasing ultrasound counts. For pregnancies with medical record data on ultrasound timing, we conducted supplementary tests to model associations by trimester of exposure.

RESULTS

Among 1524 singleton pregnancies, ultrasound indications were more common for ASD cases than controls; respectively, for each group, no indications were reported for 45.1% and 54.2% of pregnancies, while ≥2 indications were reported for 26.1% and 18.4% of pregnancies. The percentage of pregnancies with multiple ultrasounds varied by case status and the presence of ultrasound indications. However, stratified regression models showed no association between increasing ultrasound counts and case status, either for pregnancies without (aOR 1.01, 95% CI 0.92, 1.11) or with ultrasound indications (aOR 1.01, 95% CI 0.95, 1.08). Trimester-specific analyses using medical record data showed no association in any individual trimester.

CONCLUSIONS

We found no evidence that prenatal ultrasound use increases ASD risk. Study strengths included gold-standard assessments for ASD case classification, comparison of cases with controls, and a stratified sample to account for conditions associated both with increased prenatal ultrasound use and ASD.

Peri-Pregnancy Cannabis Use and Autism Spectrum Disorder in the Offspring: Findings from the Study to Explore Early Development

The association of autism spectrum disorder (ASD) with self-reported maternal cannabis use from 3 months pre-conception to delivery ("peri-pregnancy") was assessed in children aged 30-68 months, born 2003 to 2011. Children with ASD (N = 1428) were compared to children with other developmental delays/disorders (DD, N = 1198) and population controls (POP, N = 1628). Peri-pregnancy cannabis use was reported for 5.2% of ASD, 3.2% of DD and 4.4% of POP children. Adjusted odds of peri-pregnancy cannabis use did not differ significantly between ASD cases and DD or POP controls. Results were similar for any use during pregnancy. However, given potential risks suggested by underlying neurobiology and animal models, further studies in more recent cohorts, in which cannabis use and perception may have changed, are needed.

Maternal prepregnancy weight and gestational weight gain in association with autism and developmental disorders in offspring

OBJECTIVE

Maternal prepregnancy BMI and gestational weight gain (GWG) are examined in relation to autism spectrum disorder (ASD) and other developmental disorders (DD) in offspring in a multisite case-control study.

METHODS

Maternal prepregnancy BMI, obtained from medical records or self-report, was categorized as underweight, normal weight, overweight, obesity Class 1, or obesity Class 2/3. GWG was standardized for gestational age (GWG z score), and the rate (pounds/week) was categorized per adherence with clinical recommendations. Logistic regression models, adjusting for demographic factors, were used to assess associations with ASD (n = 1,159) and DD (n = 1,617), versus control children (n = 1,633).

RESULTS

Maternal obesity Class 2/3 was associated with ASD (adjusted odds ratio [AOR] = 1.87, 95% CI: 1.40-2.51) and DD (AOR = 1.61, 95% CI: 1.22-2.13). GWG z score was not associated with DD (AOR = 1.14, 95% CI: 0.95-1.36), but the GWG z score highest tertile was associated with higher odds of ASD, particularly among male children (AOR = 1.47, 95% CI: 1.15-1.88).

CONCLUSIONS

Results indicate that maternal prepregnancy severe obesity increases risk of ASD and DD in children and suggest high gestational-age-adjusted GWG is a risk factor for ASD in male children. Because maternal BMI and GWG are routinely measured and potentially modifiable, these findings could inform early interventions for high-risk mother-child dyads.

Maternal Psychiatric Conditions, Treatment With Selective Serotonin Reuptake Inhibitors, and Neurodevelopmental Disorders

BACKGROUND

This study aims to clarify relationships of maternal psychiatric conditions and selective serotonin reuptake inhibitor (SSRI) use during preconception and pregnancy with risk of neurodevelopmental disorders in offspring.

METHODS

We used data from the Study to Explore Early Development, a multisite case-control study conducted in the United States among children born between 2003 and 2011. Final study group classifications of autism spectrum disorder (ASD) (n = 1367), developmental delays or disorders (DDs) (n = 1750), and general population controls (n = 1671) were determined by an in-person standardized developmental assessment. Maternal psychiatric conditions and SSRI use during pregnancy were ascertained from both self-report and medical records. We used logistic regression to evaluate associations of ASD and DDs (vs. population controls) with maternal psychiatric conditions and SSRI treatment in pregnancy. To reduce confounding by indication, we also examined SSRI associations in analyses restricted to mothers with psychiatric conditions during pregnancy.

RESULTS

Psychiatric conditions and SSRI use during pregnancy were significantly more common among mothers of children with either ASD or DDs than among population controls. Odds of ASD were similarly elevated among mothers with psychiatric conditions who did not use SSRIs during pregnancy (adjusted odds ratio 1.81, 95% confidence interval 1.44-2.27) as in mothers who did use SSRIs (adjusted odds ratio 2.05, 95% confidence interval 1.50-2.80). Among mothers with psychiatric conditions, SSRI use was not significantly associated with ASD in offspring (adjusted odds ratio 1.14, 95% confidence interval 0.80-1.62). Primary findings for DDs exhibited similar relationships to those observed with ASD.

CONCLUSIONS

Maternal psychiatric conditions but not use of SSRIs during pregnancy were associated with increased risk of neurodevelopmental disorders in offspring.

Early Life Exposure to Air Pollution and Autism Spectrum Disorder: Findings from a Multisite Case-Control Study

BACKGROUND

Epidemiologic studies have reported associations between prenatal and early postnatal air pollution exposure and autism spectrum disorder (ASD); however, findings differ by pollutant and developmental window.

OBJECTIVES

We examined associations between early life exposure to particulate matter ≤2.5 µm in diameter (PM2.5) and ozone in association with ASD across multiple US regions.

METHODS

Our study participants included 674 children with confirmed ASD and 855 population controls from the Study to Explore Early Development, a multi-site case-control study of children born from 2003 to 2006 in the United States. We used a satellite-based model to assign air pollutant exposure averages during several critical periods of neurodevelopment: 3 months before pregnancy; each trimester of pregnancy; the entire pregnancy; and the first year of life. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for study site, maternal age, maternal education, maternal race/ethnicity, maternal smoking, and month and year of birth.

RESULTS

The air pollution-ASD associations appeared to vary by exposure time period. Ozone exposure during the third trimester was associated with ASD, with an OR of 1.2 (95% CI: 1.1, 1.4) per 6.6 ppb increase in ozone. We additionally observed a positive association with PM2.5 exposure during the first year of life (OR = 1.3 [95% CI: 1.0, 1.6] per 1.6 µg/m increase in PM2.5).

CONCLUSIONS

Our study corroborates previous findings of a positive association between early life air pollution exposure and ASD, and identifies a potential critical window of exposure during the late prenatal and early postnatal periods.

Pica, Autism, and Other Disabilities

BACKGROUND AND OBJECTIVES

Pica, the repeated ingestion of nonfood items, can be life-threatening. Although case reports describe pica in children with autism spectrum disorder (ASD) or intellectual disability (ID), there has been little systematic study of pica prevalence. We assessed pica in children 30 to 68 months of age (median = 55.4 months) with and without ASD.

METHODS

Our sample from the Study to Explore Early Development, a multisite case-control study, included children with ASD (n = 1426), children with other developmental disabilities (DDs) (n = 1735), and general population-based controls (POPs) (n = 1578). We subdivided the ASD group according to whether children had ID and the DD group according to whether they had ID and/or some ASD characteristics. Standardized developmental assessments and/or questionnaires were used to define final study groups, subgroups, and pica. We examined pica prevalence in each group and compared ASD and DD groups and subgroups to the POP group using prevalence ratios adjusted for sociodemographic factors.

RESULTS

Compared with the prevalence of pica among POPs (3.5%), pica was higher in children with ASD (23.2%) and DD (8.4%), and in the following subgroups: ASD with ID (28.1%), ASD without ID (14.0%), DD with ID (9.7%), DD with ASD characteristics (12.0%), and DD with both ID and ASD characteristics (26.3%); however, pica prevalence was not elevated in children with DD with neither ID nor ASD characteristics (3.2%). Between-group differences remained after adjustment (adjusted prevalence ratio range 1.9-8.0, all P <.05).

CONCLUSIONS

Pica may be common in young children with ASD, ASD characteristics, and ID. These findings inform the specialized health care needs of these children.

Infection and Fever in Pregnancy and Autism Spectrum Disorders: Findings from the Study to Explore Early Development

Maternal infection and fever during pregnancy have been implicated in the etiology of autism spectrum disorder (ASD); however, studies have not been able to separate the effects of fever itself from the impact of a specific infectious organism on the developing brain. We utilized data from the Study to Explore Early Development (SEED), a case-control study among 2- to 5-year-old children born between 2003 and 2006 in the United States, to explore a possible association between maternal infection and fever during pregnancy and risk of ASD and other developmental disorders (DDs). Three groups of children were included: children with ASD (N = 606) and children with DDs (N = 856), ascertained from clinical and educational sources, and children from the general population (N = 796), randomly sampled from state birth records. Information about infection and fever during pregnancy was obtained from a telephone interview with the mother shortly after study enrollment and maternal prenatal and labor/delivery medical records. ASD and DD status was determined by an in-person standardized developmental assessment of the child at 3-5 years of age. After adjustment for covariates, maternal infection anytime during pregnancy was not associated with ASD or DDs. However, second trimester infection accompanied by fever elevated risk for ASD approximately twofold (aOR = 2.19, 95% confidence interval 1.14-4.23). These findings of an association between maternal infection with fever in the second trimester and increased risk of ASD in the offspring suggest that the inflammatory response to the infectious agent may be etiologically relevant. Autism Res 2019, 12: 1551-1561. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Using data from a large multisite study in the United States-the Study to Explore Early Development-we found that women who had an infection during the second trimester of pregnancy accompanied by a fever are more likely to have children with ASD. These findings suggest the possibility that only more severe infections accompanied by a robust inflammatory response increase the risk of ASD.

Association Between Breastfeeding Initiation and Duration and Autism Spectrum Disorder in Preschool Children Enrolled in the Study to Explore Early Development

Studies report inconsistent findings on the relationship between ASD and breastfeeding. We explored associations between ASD and breastfeeding initiation (yes/no) and duration (months categorized in tertiles) in the Study to Explore Early Development, a community-based case-control study in six sites in the Unites States. We adjusted for various child and mother demographic and pregnancy factors. Breastfeeding initiation was reported in 85.7% of mothers of children with ASD and 90.6% of mothers of controls. After adjustment, we found no significant difference in breastfeeding initiation (adjusted odds-ratio [aOR]: 0.88 and 95% confidence interval (CI) 0.60-1.28). However, mothers of children with ASD were less likely to report duration of breastfeeding in the high (≥12 months) versus low tertile (<6 months) (aOR and 95% CI: 0.61 [0.45-0.84]) or the middle (6-<12 months) versus low tertile (0.72: 0.54-0.98). The association of ASD and breastfeeding duration was slightly attenuated when the presence of the broader autism phenotype (BAP) in the mother was accounted for, but still remained for the highest tertile. This association does not appear to be totally explained by maternal BAP. We were unable to distinguish whether the difference in duration was due to difficulties breastfeeding children who later develop ASD, other factors not adjusted in our study, or greater ASD risk resulting from shorter breastfeeding duration. Longitudinal studies that compare reasons why mothers stop breastfeeding between ASD and controls and establish a temporal relation between ASD and breastfeeding are needed. Future studies should also evaluate interactions between ASD risk genes and breastfeeding. Autism Research 2019, 12: 816-829. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: In this study, we compared breastfeeding practices between mothers of children with and without autism spectrum disorder (ASD). We found that the percentage of mothers who started breastfeeding was similar between the two groups, but mothers of children with ASD breastfed for a shorter amount of time compared to mothers of children without ASD. Future studies are needed to evaluate the reasons why the duration of breastfeeding was shorter for mothers of children with ASD compared to those without ASD.

Maternal diabetes and hypertensive disorders in association with autism spectrum disorder

Previous studies have shown complications of pregnancy, often examined in aggregate, to be associated with autism spectrum disorder (ASD). Results for specific complications, such as maternal diabetes and hypertension, have not been uniformly consistent and should be investigated independently in relation to ASD in a large community-based sample. The Study to Explore Early Development (SEED), a US multisite case-control study, enrolled children born in 2003-2006 at 2-5 years of age. Children were classified into three groups based on confirmation of ASD (n = 698), non-ASD developmental delay (DD; n = 887), or controls drawn from the general population (POP; n = 979). Diagnoses of any diabetes or hypertensive disorder during pregnancy were identified from prenatal medical records and maternal self-report. Logistic regression models estimated adjusted odds ratios (aOR) and confidence intervals (CI) adjusting for maternal age, race/ethnicity, education, smoking during pregnancy, and study site. Models for hypertension were additionally adjusted for parity and plurality. Among 2,564 mothers, we identified 246 (9.6%) with any diabetes and 386 (15.1%) with any hypertension in pregnancy. After adjustment for covariates, any diabetes during pregnancy was not associated with ASD (aOR = 1.10 [95% CI 0.77, 1.56]), but any hypertension was associated with ASD (aOR = 1.69 [95% CI 1.26, 2.26]). Results were similar for DD, and any diabetes (aOR = 1.29 [95% CI 0.94, 1.78]) or any hypertension (aOR = 1.71 [95% CI 1.30, 2.25]). Some pregnancy complications, such as hypertension, may play a role in autism etiology and can possibly serve as a prompt for more vigilant ASD screening efforts. Autism Res 2019, 12: 967-975. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We studied if common complications in pregnancy are associated with autism spectrum disorder (ASD) in a large sample of mothers and children. Our results show an association between conditions marked by high blood pressure and ASD, but no association with conditions marked by high blood sugar and ASD. Associations were similar for children who had a developmental disorder that was not ASD, suggesting that this relationship may not be specific to ASD.