Research review: Birth by caesarean section and development of autism spectrum disorder and attention-deficit/hyperactivity disorder: a systematic review and meta-analysis

The association between bisphenol a exposure and attention deficit hyperactivity disorder in children: a meta-analysis of observational studies

INTRODUCTION

The association between Bisphenol A (BPA) exposure and attention deficit hyperactivity disorder (ADHD) has been a controversial topic. Objective: To evaluate the connection between BPA exposure and ADHD.

CONTENT

We search Scopus, Web of Science, and Medline databases until August 2022. The meta-analysis was performed by using the software Stata 12.0 to calculate the combined effect value Odds ratios (OR) and 95% confidence interval (95%CI). A total of 8 studies were included in this meta-analysis, including 5,710 children. Using the random effect model, it was found that compared with the lowest level of BPA exposure, the OR (95%CI) value of urine BPA exposure and ADHD in the highest level of BPA exposure was 1.76 (1.13-2.74).

SUMMARY AND OUTLOOK

Based on the current meta-analysis results, BPA exposure may be a significant contributing factor to the development of ADHD in children.

Prenatal Gut Microbiota Predicts Temperament in Offspring at 1-2 Years

The purpose of this study was to explore whether prenatal gut microbiota (GM) and its functions predict the development of offspring temperament. A total of 53 mothers with a 1-year-old child and 41 mothers with a 2-year-old child were included in this study using a mother-infant cohort from central China. Maternal fecal samples collected during the third trimester were analyzed using 16S rRNA V3-V4 gene sequences. Temperament of the child was measured by self-reported data according to the primary caregiver. The effects of GM in mothers on offspring's temperament were evaluated using multiple linear regression models. The results demonstrated that the alpha diversity index Simpson of prenatal GM was positively associated with the activity level of offspring at 1 year (adj. P = .036). Bifidobacterium was positively associated with high-intensity pleasure characteristics of offspring at 1 year (adj. P = .031). Comparatively, the presence of Bifidobacterium found in the prenatal microbiome was associated with low-intensity pleasure characteristics in offspring at 2 years (adj. P = .031). There were many significant associations noted among the functional pathways of prenatal GM and temperament of offspring at 2 years. Our findings support the maternal-fetal GM axis in the setting of fetal-placental development with subsequent postnatal neurocognitive developmental outcomes, and suggest that early childhood temperament is in part associated with specific GM in the prenatal setting.

Excluding autism or excluding everything? The problem of broad definitions in the England and Wales Draft Mental Health Bill

The recent Draft Mental Health Bill for England and Wales proposes changes to the Mental Health Act 1983 which will include, for the first time, a legal definition of autism. This article explores the specific potential issue that the definition, owing to its breadth, potentially encompasses a number of conditions other than autism, consequently leaving the definitionally dependent concept of 'psychiatric disorder' significantly narrowed in scope. The potential implications of this - primarily the concern that a range of other conditions and presentations could be unintentionally excluded from the scope of the civil powers in the Mental Health Act - are discussed.

Probiotics as a Promising Therapy in Improvement of Symptoms in Children With ADHD: A Systematic Review

BACKGROUND

ADHD is widely recognized as the most prevalent neurodevelopmental disorder in children. Recently, the potential role of gut microbiota as an etiological factor in ADHD has gained attention. This systematic review aims to investigate the potential impact of probiotic supplements on alleviating ADHD symptoms and influencing behavior.

METHODS

PubMed, Web of Science, Cochrane Library, and SCOPUS were searched from inception to May 2023. Only randomized controlled trials that have suitable data of the effects of probiotics/synbiotics on children with ADHD were enrolled. The risk of bias of the included studies was assessed by Cochrane Collaboration risk of bias tool.

RESULTS

Five related randomized controlled trial were evaluated in the current review. Types of interventions ranged from single/multi strain probiotics to synbiotic. The duration of intervention in all of the studies were 2 to 3 months. The assessed outcomes were very diverse and different tools were used to report the symptoms in children. Among those which used Conners' Parent Rating Scale, a decrease in the total score occurred in the probiotic group, compared to the placebo group. An improvement in both intervention and control groups was seen in one study which used ADHD-Rating Scale.

CONCLUSION

In summary, the combined findings from the reviewed studies suggest that probiotic supplements might potentially serve as a complementary intervention for ADHD. However, given the small number of studies, limited sample sizes, and the diversity of probiotic strains, further research is needed to clarify the effects of probiotics in children with ADHD. The observed tolerability of probiotics is noteworthy as none of the studies report adverse effects.

A case-control study on pre-, peri-, and neonatal risk factors associated with autism spectrum disorder among Armenian children

We aimed to investigate the role of pre-, peri- and neonatal risk factors in the development of autism spectrum disorder (ASD) among Armenian children with the goal of detecting and addressing modifiable risk factors to reduce ASD incidence. For this purpose a retrospective case-control study using a random proportional sample of Armenian children with ASD to assess associations between various factors and ASD was conducted. The study was approved by the local ethical committee, and parental written consent was obtained. A total of 168 children with ASD and 329 controls were included in the analysis. Multivariable logistic regression analysis revealed that male gender, maternal weight gain, use of MgB6, self-reported stress during the pregnancy, pregnancy with complications, as well as use of labor-inducing drugs were associated with a significant increase in the odds of ASD, whereas Duphaston use during pregnancy, the longer interpregnancy interval and birth height were associated with decreased odds of ASD. These findings are pertinent as many identified factors may be preventable or modifiable, underscoring the importance of timely and appropriate public health strategies aimed at disease prevention in pregnant women to reduce ASD incidence.

Identifying Risk Factors for Attention-Deficit/Hyperactivity Disorder (ADHD): a Public Health Concern and Opportunity

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders with significant individual and societal negative impacts of the disorder continuing into adulthood (Danielson et al. in Journal of Clinical Child and Adolescent Psychology, in press; Landes and London in Journal of Attention Disorders 25:3-13, 2021). Genetic and environmental risk (e.g., modifiable exposures such as prenatal tobacco exposure and child maltreatment) for ADHD is likely multifactorial (Faraone et al. in Neuroscience & Biobehavioral Reviews 128:789-818, 2021). However, the evidence for potentially modifiable contextual risks is spread across studies with different methodologies and ADHD criteria limiting understanding of the relationship between early risk factors and later childhood ADHD. Using common methodology across six meta-analyses (Bitsko et al. in Prevention Science, 2022; Claussen et al. in Prevention Science 1-23, 2022; Dimitrov et al. in Prevention Science, 2023; Maher et al. in Prevention Science, 2023; Robinson, Bitsko et al. in Prevention Science, 2022; So et al. in Prevention Science, 2022) examining 59 risk factors for childhood ADHD, the papers in this special issue use a public health approach to address prior gaps in the literature. This introductory paper provides examples of comprehensive public health approaches focusing on policy, systems, and environmental changes across socio-ecological contexts to improve health and wellbeing through prevention, early intervention, and support across development using findings from these meta-analyses. Together, the findings from these studies and a commentary by an author independent from the risk studies have the potential to minimize risk conditions, prioritize prevention efforts, and improve the long-term health and wellbeing of children and adults with ADHD.

Functional contribution of the intestinal microbiome in autism spectrum disorder, attention deficit hyperactivity disorder, and Rett syndrome: a systematic review of pediatric and adult studies

Introduction

Critical phases of neurodevelopment and gut microbiota diversification occur in early life and both processes are impacted by genetic and environmental factors. Recent studies have shown the presence of gut microbiota alterations in neurodevelopmental disorders. Here we performed a systematic review of alterations of the intestinal microbiota composition and function in pediatric and adult patients affected by autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and Rett syndrome (RETT).

Methods

We searched selected keywords in the online databases of PubMed, Cochrane, and OVID (January 1980 to December 2021) with secondary review of references of eligible articles. Two reviewers independently performed critical appraisals on the included articles using the Critical Appraisal Skills Program for each study design.

Results

Our systematic review identified 18, 7, and 3 original articles describing intestinal microbiota profiles in ASD, ADHD, and RETT, respectively. Decreased Firmicutes and increased Bacteroidetes were observed in the gut microbiota of individuals affected by ASD and ADHD. Proinflammatory cytokines, short-chain fatty acids and neurotransmitter levels were altered in ASD and RETT. Constipation and visceral pain were related to changes in the gut microbiota in patients affected by ASD and RETT. Hyperactivity and impulsivity were negatively correlated with Faecalibacterium (phylum Firmicutes) and positively correlated with Bacteroides sp. (phylum Bacteroidetes) in ADHD subjects. Five studies explored microbiota-or diet-targeted interventions in ASD and ADHD. Probiotic treatments with Lactobacillus sp. and fecal microbiota transplantation from healthy donors reduced constipation and ameliorated ASD symptoms in affected children. Perinatal administration of Lactobacillus sp. prevented the onset of Asperger and ADHD symptoms in adolescence. Micronutrient supplementation improved disease symptomatology in ADHD without causing significant changes in microbiota communities' composition.

Discussion

Several discrepancies were found among the included studies, primarily due to sample size, variations in dietary practices, and a high prevalence of functional gastrointestinal symptoms. Further studies employing longitudinal study designs, larger sample sizes and multi-omics technologies are warranted to identify the functional contribution of the intestinal microbiota in developmental trajectories of the human brain and neurobehavior.

Systematic review registration

https://clinicaltrials.gov/, CRD42020158734.

Probiotics as modulators of gut-brain axis for cognitive development

Various microbial communities reside in the gastrointestinal tract of humans and play an important role in immunity, digestion, drug metabolism, intestinal integrity, and protection from pathogens. Recent studies have revealed that the gut microbiota (GM) is involved in communication with the brain, through a bidirectional communication network known as the gut-brain axis. This communication involves humoral, immunological, endocrine, and neural pathways. Gut dysbiosis negatively impacts these communication pathways, leading to neurological complications and cognitive deficits. Both pre-clinical and clinical studies have demonstrated that probiotics can restore healthy GM, reduce intestinal pH, and reduce inflammation and pathogenic microbes in the gut. Additionally, probiotics improve cell-to-cell signaling and increase blood-brain-derived neurotrophic factors. Probiotics emerge as a potential approach for preventing and managing neurological complications and cognitive deficits. Despite these promising findings, the safety concerns and possible risks of probiotic usage must be closely monitored and addressed. This review article provides a brief overview of the role and significance of probiotics in cognitive health.

Development and validation of a risk score model for predicting autism based on pre- and perinatal factors

Background

The use of pre- and perinatal risk factors as predictive factors may lower the age limit for reliable autism prediction. The objective of this study was to develop a clinical model based on these risk factors to predict autism.

Methods

A stepwise logistic regression analysis was conducted to explore the relationships between 28 candidate risk factors and autism risk among 615 Han Chinese children with autism and 615 unrelated typically developing children. The significant factors were subsequently used to create a clinical risk score model. A chi-square automatic interaction detector (CHAID) decision tree was used to validate the selected predictors included in the model. The predictive performance of the model was evaluated by an independent cohort.

Results

Five factors (pregnancy influenza-like illness, pregnancy stressors, maternal allergic/autoimmune disease, cesarean section, and hypoxia) were found to be significantly associated with autism risk. A receiver operating characteristic (ROC) curve indicated that the risk score model had good discrimination ability for autism, with an area under the curve (AUC) of 0.711 (95% CI=0.679-0.744); in the external validation cohort, the model showed slightly worse but overall similar predictive performance. Further subgroup analysis indicated that a higher risk score was associated with more behavioral problems. The risk score also exhibited robustness in a subgroup analysis of patients with mild autism.

Conclusion

This risk score model could lower the age limit for autism prediction with good discrimination performance, and it has unique advantages in clinical application.

Adolescence, the Microbiota-Gut-Brain Axis, and the Emergence of Psychiatric Disorders

Second only to early life, adolescence is a period of dramatic change and growth. For the developing young adult, this occurs against a backdrop of distinct environmental challenges and stressors. A significant body of work has identified an important role for the microbiota-gut-brain (MGB) axis in the development and function of the brain. Given that the MGB axis is both highly plastic during the teenage years and vulnerable to environmental stressors, more attention needs to be drawn to its potential role in the emergence of psychiatric illnesses, many of which first manifest during adolescence. Here, we review the current literature surrounding the developing microbiome, enteric nervous system, vagus nerve, and brain during the adolescent period. We also examine preclinical and clinical research involving the MGB axis during this dynamic developmental window and argue that more research is needed to further understand the role of the MGB in the pathogenesis of brain disorders. Greater understanding of the adolescent MGB axis will open up the exciting potential for new microbial-based therapeutics for the treatment of these often-refractory psychiatric illnesses.

Association of perinatal factors with neurodevelopmental referrals in a population-based cohort study in Japan

Although the causes of neurodevelopmental disorders remain unknown, several environmental risk factors have attracted considerable attention. We conducted a retrospective, longitudinal, population-based cohort study using data from infant health examinations of children born to mothers with pregnancies between April 1, 2014 and March 31, 2016 in Kobe City to identify the perinatal factors associated with neurodevelopmental referrals in 3-year-old children. There were 15,223 and 1283 children in the normal and referral groups, respectively. Neurodevelopmental referrals at the health checkup for 3-year-old children were significantly associated with the lack of social support during pregnancy (adjusted odds ratio [aOR] 1.99, 99% CI 1.14-3.45, p = 0.001), history of psychiatric consultation (aOR 1.56, 99% CI 1.10-2.22, p = 0.001), no social assistance post-delivery (aOR 1.49, 99% CI 1.03-2.16, p = 0.006), Edinburgh Post-natal Depression Scale (EPDS) score ≥ 9 (aOR 1.36, 99% CI 1.01-1.84, p = 0.008), infant gender (male) (aOR 2.51, 99% CI 2.05-3.06, p < 0.001), and cesarean delivery (aOR 1.39, 99% CI 1.11-1.75, p < 0.001). In conclusion, this exploratory study in the general Japanese population identified six perinatal factors associated with neurodevelopmental referrals in 3-year-old children: infant gender (male), cesarean section, maternal history of psychiatric consultation, EPDS score ≥ 9, lack of social support during pregnancy, and no social assistance post-delivery.

Effect of cesarean section on the risk of autism spectrum disorders/attention deficit hyperactivity disorder in offspring: a meta-analysis

PURPOSE

This study was conducted to investigate the relationship between cesarean section (CS) offspring and autism spectrum disorders (ASD)/attention deficit hyperactivity disorder (ADHD).

METHODS

Searching of the databases (PubMed, Web of Science, Embase, and Cochrane Library) for studies on the relationship between mode of delivery and ASD/ADHD until August 2022. The primary outcome was the incidence of ASD/ADHD in the offspring.

RESULTS

This meta-analysis included 35 studies (12 cohort studies and 23 case-control studies). Statistical results showed a higher risk of ASD (odds ratio (OR) = 1.25, P < 0.001) and ADHD (OR = 1.11, P < 0.001) in CS offspring compared to the VD group. Partial subgroup analysis showed no difference in ASD risk between CS and VD offspring in sibling-matched groups (OR = 0.98, P = 0.625). The risk of ASD was higher in females (OR = 1.66, P = 0.003) than in males (OR = 1.17, P = 0.004) in the CS offspring compared with the VD group. There was no difference in the risk of ASD between CS under regional anesthesia group and VD group (OR = 1.07, P = 0.173). However, the risk of ASD was higher in the CS offspring under general anesthesia than in the VD offspring (OR = 1.62, P < 0.001). CS offspring developed autism (OR = 1.38, P = 0.011) and pervasive developmental disorder-not otherwise specified (OR = 1.46, P = 0.004) had a higher risk than VD offspring, but there was no difference in Asperger syndrome (OR = 1.19, P = 0.115). Offspring born via CS had a higher incidence of ADHD in different subgroup analyses (sibling-matched, type of CS, and study design).

CONCLUSIONS

In this meta-analysis, CS was a risk factor for ASD/ADHD in offspring compared with VD.

The many faces of microbiota-gut-brain axis in autism spectrum disorder

The gut-brain axis is gaining more attention in neurodevelopmental disorders, especially autism spectrum disorder (ASD). Many factors can influence microbiota in early life, including host genetics and perinatal events (infections, mode of birth/delivery, medications, nutritional supply, and environmental stressors). The gut microbiome can influence blood-brain barrier (BBB) permeability, drug bioavailability, and social behaviors. Developing microbiota-based interventions such as probiotics, gastrointestinal (GI) microbiota transplantation, or metabolite supplementation may offer an exciting approach to treating ASD. This review highlights that RNA sequencing, metabolomics, and transcriptomics data are needed to understand how microbial modulators can influence ASD pathophysiology. Due to the substantial clinical heterogeneity of ASD, medical caretakers may be unlikely to develop a broad and effective general gut microbiota modulator. However, dietary modulation followed by administration of microbiota modulators is a promising option for treating ASD-related behavioral and gastrointestinal symptoms. Future work should focus on the accuracy of biomarker tests and developing specific psychobiotic agents tailored towards the gut microbiota seen in ASD patients, which may include developing individualized treatment options.

Environmental Risk Factors in Autism Spectrum Disorder: A Narrative Review

Existing evidence indicates that environmental factors might contribute up to 50% of the variance in autism spectrum disorder (ASD) risk. This structured narrative review offers a comprehensive synthesis of current knowledge on environmental risk factors in ASD, including evaluation of conflicting evidence, exploration of underlying mechanisms, and suggestions for future research directions. Analysis of diverse epidemiological investigations indicates that certain environmental factors, including advanced parental age, preterm birth, delivery complications, and exposure to toxic metals, drugs, air pollutants, and endocrine-disrupting chemicals, are linked to an increased ASD risk through various mechanisms such as oxidative stress, inflammation, hypoxia, and its consequences, changes in neurotransmitters, disruption of signaling pathways and some others. On the other hand, pregnancy-related factors such as maternal diabetes, maternal obesity, and caesarian section show a weaker association with ASD risk. At the same time, other environmental factors, such as vaccination, maternal smoking, or alcohol consumption, are not linked to the risk of ASD. Regarding nutritional elements data are inconclusive. These findings highlight the significance of environmental factors in ASD etiology and emphasize that more focused research is needed to target the risk factors of ASD. Environmental interventions targeting modifiable risk factors might offer promising avenues for ASD prevention and treatment.

A systematic meta-review of systematic reviews on attention deficit hyperactivity disorder

BACKGROUND

There are now hundreds of systematic reviews on attention deficit hyperactivity disorder (ADHD) of variable quality. To help navigate this literature, we have reviewed systematic reviews on any topic on ADHD.

METHODS

We searched MEDLINE, PubMed, PsycINFO, Cochrane Library, and Web of Science and performed quality assessment according to the Joanna Briggs Institute Manual for Evidence Synthesis. A total of 231 systematic reviews and meta-analyses met the eligibility criteria.

RESULTS

The prevalence of ADHD was 7.2% for children and adolescents and 2.5% for adults, though with major uncertainty due to methodological variation in the existing literature. There is evidence for both biological and social risk factors for ADHD, but this evidence is mostly correlational rather than causal due to confounding and reverse causality. There is strong evidence for the efficacy of pharmacological treatment on symptom reduction in the short-term, particularly for stimulants. However, there is limited evidence for the efficacy of pharmacotherapy in mitigating adverse life trajectories such as educational attainment, employment, substance abuse, injuries, suicides, crime, and comorbid mental and somatic conditions. Pharmacotherapy is linked with side effects like disturbed sleep, reduced appetite, and increased blood pressure, but less is known about potential adverse effects after long-term use. Evidence of the efficacy of nonpharmacological treatments is mixed.

CONCLUSIONS

Despite hundreds of systematic reviews on ADHD, key questions are still unanswered. Evidence gaps remain as to a more accurate prevalence of ADHD, whether documented risk factors are causal, the efficacy of nonpharmacological treatments on any outcomes, and pharmacotherapy in mitigating the adverse outcomes associated with ADHD.

Preterm Birth by Cesarean Section: The Gut-Brain Axis, a Key Regulator of Brain Development

Understanding the long-term functional implications of gut microbial communities during the perinatal period is a bourgeoning area of research. Numerous studies have revealed the existence of a "gut-brain axis" and the impact of an alteration of gut microbiota composition in brain diseases. Recent research has highlighted how gut microbiota could affect brain development and behavior. Many factors in early life such as the mode of delivery or preterm birth could lead to disturbance in the assembly and maturation of gut microbiota. Notably, global rates of cesarean sections (C-sections) have increased in recent decades and remain important when considering premature delivery. Both preterm birth and C-sections are associated with an increased risk of neurodevelopmental disorders such as autism spectrum disorders, with neuroinflammation a major risk factor. In this review, we explore links between preterm birth by C-sections, gut microbiota alteration, and neuroinflammation. We also highlight C-sections as a risk factor for developmental disorders due to alterations in the microbiome.

Association of labor epidural analgesia exposure with long-term risk of autism spectrum disorder in offspring: A meta-analysis of observational studies

LAY ABSTRACT

A previous meta-analysis has demonstrated a superior analgesic efficacy of epidural analgesia (e.g. labor epidural analgesia) in comparison with non-epidural approaches. The widely accepted safety of labor epidural analgesia also endorses its current popularity in obstetric practice. However, the results of a recent large-scale longitudinal study that demonstrated a significant increase in risk of autism spectrum disorder in offspring from mothers with labor epidural analgesia exposure have raised some concerns over the safety of its use. The current meta-analysis aimed at examining the strength of evidence regarding this issue based on updated clinical data. Through systematically reviewing seven eligible observational studies involving 4,021,406 children from electronic databases, our results showed a slight but statistically significant increase in risk of autism spectrum disorder in children with exposure to labor epidural analgesia compared with those without. The finding was consistent in subgroup analysis focusing on siblings and children delivered vaginally. Nevertheless, despite the tendency of an increased risk of autism spectrum disorder in children exposed to labor epidural analgesia <4 h, this effect was not observed in those exposed to labor epidural analgesia >8 h (data from two studies). In conclusion, the level of evidence linking labor epidural analgesia to autism spectrum disorder development in offspring was very low based on the latest data because of the small effect size and the finding of a lack of cumulative dose-response effect in the current analysis. Further studies are warranted to provide an insight into this issue.

Maternal- and child-related risk factors for autism during the perinatal period

Background

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder commonly prevalent in children worldwide including KSA. It causes disability in social interaction, communication, and restrictive and repetitive behaviors. Detecting risk factors for ASD could help initiate screening and risk prevention approaches. Herein, this study aimed to detect several maternal and neonatal risk factors for ASD in KSA.

Results

Ninety-four cases and 282 control completed an online survey tool. The survey items were close-ended questions. Participants were asked about maternal-related risk factors for autism during perinatal period. The logistic regression model revealed having a child diagnosed with autism with two predictors: factors related to the mother and factors related to the baby during perinatal period. The whole model was sig (p < 0.0001). The factors related to the baby have more impact on developing autism than maternal factors (OR is 3 vs 2.3, respectively, p < 0.01 for both).

Conclusion

The findings of this study will be beneficial for subsequent nationwide screenings and educational programs. The study brought to light the potential for identifying children in need of early intervention.

Association between maternal labour epidural analgesia and autistic traits in offspring

STUDY OBJECTIVE

Studies investigating associations between maternal epidural analgesia (MEA) and autism spectrum disorder (ASD) in the offspring are conflicting and lack prospective neurobehavioral follow-up assessments for autistic traits. We aim to prospectively investigate associations between MEA and autistic traits in the offspring.

DESIGN

Prospective neurobehavioral observational cohort study.

SETTING

Singaporean tertiary healthcare institutions.

PATIENTS

Participants recruited were singleton non-IVF children, >36 weeks gestation, delivered via normal vaginal delivery by mothers >18 years of age, delivered in Singapore from June 2009-September 2010 and followed up over 7 years.

INTERVENTIONS

Exposure to maternal epidural analgesia during delivery.

MEASUREMENTS

The primary outcome is an abnormal Social Responsiveness Scale (SRS) T score at 7 years (≥60 points). Secondary outcomes include the diagnosis of ASD and abnormal scores for autistic traits assessed via a neurobehavioral battery comprising: CBCL (child behavioural checklist), Q-CHAT (Quantitative Checklist for Autism in Toddlers), and Bayley-III. Multivariable analyses adjusting for maternal and offspring characteristics were performed.

MAIN RESULTS

704 out of 769 mother-child dyads recruited fulfilled the criteria for analysis. 365/704 mothers received MEA. The incidence of an abnormal SRS score at 7 years in offspring exposed to MEA was 19.9%, and 26.1% in non-exposed offspring (p = 0.154). Multivariable analysis did not demonstrate a significant association between MEA and abnormal SRS scores at 7 years (O.R.0.726, 95% C·I. 0.394-1.34, p = 0.305). After adjustment for maternal and fetal demographics, exposure to MEA was not significantly associated with an abnormal screen in all other tests for autistic traits. The clinical incidence of ASD was 1.76% in children without exposure to MEA, and 2.32% in children with MEA exposure (p = 0.506).

CONCLUSIONS

MEA is not significantly associated with the development of ASD and autistic traits in offspring, assessed over 7 years. Results should be taken into perspective given our wide confidence intervals and small cohort size.

Association between Cesarean section and neurodevelopmental disorders in a Japanese birth cohort: the Japan Environment and Children's Study

BACKGROUND

The long-term effects of a Cesarean section (CS) birth on child neurodevelopment are of increasing interest. In this study, we examined the associations between mode of delivery and presence of neurodevelopmental disorders in toddlers. Moreover, given that the prevalence of several neurodevelopmental disorders such as autism spectrum disorder (ASD) is known to differ by sex, we also investigated these associations separately in male and female toddlers.

METHODS

We investigated 65,701 mother-toddler pairs from the Japan Environment and Children's Study, a nationally representative children's cohort study. To investigate the associations between mode of delivery (CS or vaginal delivery) and neurodevelopmental disorders (motor delay, intellectual disability, and ASD) in 3-year-old toddlers as a whole and stratified by sex, we used logistic regression models to calculate adjusted odds ratios (aORs) with 95% confidence intervals (CIs).

RESULTS

The morbidity of ASD at age 3 years was higher for children delivered by CS than those delivered vaginally (aOR 1.38, 95% CI 1.04-1.83). However, no such difference was evident in the case of motor delay or intellectual disability (aOR 1.33, 95% CI 0.94-1.89; aOR 1.18, 95% CI 0.94-1.49, respectively). In the analysis by sex, CS was not associated with increased risk of any of the neurodevelopmental disorders in males, but it was associated with increased risks of motor delay (aOR 1.88, 95% CI 1.02-3.47) and ASD (aOR 1.82, 95% CI 1.04-3.16) in females.

CONCLUSIONS

This study provides evidence of significant associations between mode of delivery and neurodevelopmental disorders in early childhood. Females may be more sensitive to the effects of CS than males.

Exploring potential impacts of pregnancy-related maternal immune activation and extracellular vesicles on immune alterations observed in autism spectrum disorder

Autism Spectrum Disorder (ASD) is a set of neurodevelopmental disorders usually observed in early life, with impacts on behavioral and social skills. Incidence of ASD has been dramatically increasing worldwide, possibly due to increase in awareness/diagnosis as well as to genetic and environmental triggers. Currently, it is estimated that ∼1% of the world population presents ASD symptoms. In addition to its genetic background, environmental and immune-related factors also influence the ASD etiology. In this context, maternal immune activation (MIA) has recently been suggested as a component potentially involved in ASD development. In addition, extracellular vesicles (EVs) are abundant at the maternal-fetal interface and are actively involved in the immunoregulation required for a healthy pregnancy. Considering that alterations in concentration and content of EVs have also been associated with ASD, this article raises a debate about the potential roles of EVs in the processes surrounding MIA. This represents the major differential of the present review compared to other ASD studies. To support the suggested correlations and hypotheses, findings regarding the roles of EVs during pregnancy and potential influences on ASD are discussed, along with a review and update concerning the participation of infections, cytokine unbalances, overweight and obesity, maternal anti-fetal brain antibodies, maternal fever, gestational diabetes, preeclampsia, labor type and microbiota unbalances in MIA and ASD.

Effects of Exposure to Formal Aquatic Activities on Babies Younger Than 36 Months: A Systematic Review

This systematic review investigated the possible effects of exposing infants to formal activities in aquatic environments. A literature search of eight databases was concluded on 12 December 2022. Studies were eligible if they: (i) focused on 0-36 months of age infants, (ii) addressed the exposure of infants to formal aquatic activities, and (iii) compared the 'same condition of aquatic exposure with the control' or 'before and after exposure'. The PRISMA protocol was used. Articles considered for inclusion (n = 18) were clustered in the health, development, and physiological outcome domains. The results show that research is focused on indoor activities, mainly in baby swimming programs and baby aquatic therapy interventions. Swimming and aquatic therapy practices are generally safe for babies' health, and there are benefits to preterm and newborns exposed to aquatic therapy once the physiological parameters are maintained in normal and safe patterns. A positive effect is also suggested in general gross and fine motor skills, visual motion perception, cognitive flexibility, and response selection accuracy for infants who participated in aquatic programs. Further investigation with high-quality experimental designs is required to establish the effect of exposure of infants to formal aquatic activities (Systematic Review Registration: CRD42021248054).

Association between birth by caesarian section and anxiety, self-harm: a gene-environment interaction study using UK Biobank data

BACKGROUND

Limited efforts have been paid to explore the underlying genetic mechanisms of birth by caesarian section (CS) affecting the risks of adult anxiety and self-harm.

METHODS

Using UK Biobank cohort, the logistic regression model was first applied to evaluate the associations of adult anxiety and self-harm with birth by CS. Using birth by CS as exposure variables, genome-wide by environment interaction study (GWEIS) was then applied by PLINK2.0 to identify associated genes interacting with birth by CS for anxiety and self-harm.

RESULTS

In the observational study, significant associations were observed between birth by CS and anxiety (odds ratio (OR) = 1.24; 95% confidence interval (CI), 1.12-1.38; P = 4.86 × 10^- 5), and self-harm (OR = 1.12; 95% CI, 1.01-1.24; P = 2.90 × 10^- 2). GWEIS revealed multiple suggestive genes interacted with birth by CS for anxiety, such as DKK2 (rs13137764, P = 1.24 × 10^- 9, adjusted P = 2.68 × 10^- 7) and ATXN1 (rs62389045, P = 4.38 × 10^- 8, adjusted P = 3.55 × 10^- 6). For self-harm, significant gene-environment interactions of birth by CS on self-harm were detected, such as ALDH1A2 (rs77828167, P = 1.62 × 10^- 8; rs116899929, P = 1.92 × 10^- 8) and DAB1 (rs116124269, P = 3.20 × 10^- 8; rs191070006, P = 3.63 × 10^- 8).

CONCLUSIONS

Our results suggested that birth by CS was associated with the risk of adult anxiety and self-harm. We also discovered some genes interacted with birth by CS might influence the risk of anxiety and self-harm, which may provide novel clues for the pathogenesis of those mental disorders.

Lasting consequences on physiology and social behavior following cesarean delivery in prairie voles

Cesarean delivery is associated with diminished plasma levels of several 'birth-signaling' hormones, such as oxytocin and vasopressin. These same hormones have been previously shown to exert organizational effects when acting in early life. For example, our previous work found a broadly gregarious phenotype in prairie voles exposed to oxytocin at birth. Meanwhile, cesarean delivery has been previously associated with changes in social behavior and metabolic processes related to oxytocin and vasopressin. In the present study, we investigated the long-term neurodevelopmental consequences of cesarean delivery in prairie voles. After cross-fostering, vole pups delivered either via cesarean or vaginal delivery were studied throughout development. Cesarean-delivered pups responded to isolation differently in terms of their vocalizations (albeit in opposite directions in the two experiments), huddled in less cohesive groups under warmed conditions, and shed less heat. As young adults, we observed no differences in anxiety-like or alloparental behavior. However, in adulthood, cesarean-delivered voles of both sexes failed to form partner preferences with opposite sex conspecifics. In a follow-up study, we replicated this deficit in partner-preference formation among cesarean-delivered voles and were able to normalize pair-bonding behavior by treating cesarean-delivered vole pups with oxytocin (0.25 mg/kg) at delivery. Finally, we detected minor differences in regional oxytocin receptor expression within the brains of cesarean-delivered voles, as well as microbial composition of the gut. Gene expression changes in the gut epithelium indicated that cesarean-delivered male voles have altered gut development. These results speak to the possibility of unintended developmental consequences of cesarean delivery, which currently accounts for 32.9 % of deliveries in the U.S. and suggest that further research should be directed at whether hormone replacement at delivery influences behavioral outcomes in later life.

Associations of prenatal PFAS exposure and early childhood neurodevelopment: Evidence from the Shanghai Maternal-Child Pairs Cohort

Epidemiological data on the effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) on infant neurodevelopment trajectories are far from being sufficiently addressed. In this study, 1285 mother-child pairs were recruited during 2016-2017. A high-performance liquid chromatography-triple quadrupole mass spectrometer was used to measure 16 PFAS levels in cord serum. Ages and Stages Questionnaires were used to examine children's neurodevelopment at 2, 6, 12, and 24 months of age. Group-based trajectory models were applied to derive the neurodevelopmental trajectories. Children with relatively low scores from 2 to 24 months were classified into a low-score group and were used as a risk group in each domain. Multiple linear regression, logistic regression, and quantile-based g-computation were performed to assess associations of single or mixture PFAS exposures with neurodevelopment and trajectories. Perfluorooctane sulphonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), and 6:2 chlorinated polyfluorooctane ether sulfonate (6:2Cl-PFESA) were detected in over 90 % samples. PFOA had the highest concentration (median: 4.61 μg/L). Each ln-unit (μg/L) increase of PFAS (e.g., PFOA, PFOS, PFHxS, 6:2Cl-PFESA) was associated with poor scores of communication domain at 6 months, with the effect size ranging from -0.69 to -0.44. PFOS (OR: 1.14, (1.03, 1.26), PFDA (OR:1.08, (1.02, 1.15)), PFHxS (OR:1.31, (1.12, 1.56)), and 6:2Cl-PFESA (OR:1.08, (1.00, 1.16)) were associated with an increased risk of being in the low-score group in the early childhood communication domain's trajectory. Each mixture quartile increment was associated with a 1.60 (-2.76, -0.45) decrease in communication domain scores of 6-month-old infants, and the mixture effect was mainly attributed to PFOS. Each mixture quartile increase was associated with a 1.23-fold (1.03, 1.46) risk of being in the low-score group of the communication domain, and the mixture effect was mainly attributed to PFOS. In conclusion, PFAS and their mixtures might adversely affect childhood neurodevelopment. The gender-specific associations existed in the above associations.

Risks of attention-deficit/hyperactivity disorder, autism spectrum disorder, and intellectual disability in children delivered by caesarean section: A population-based cohort study

This population-based study investigated the risks of attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and intellectual disabilities among children delivered by Cesarean section (CS) in comparison with those who were delivered by vaginal delivery (VD). The Taiwan Maternal and Child Health Database from 2004 to 2016 registered 675,718 and 1,208,983 children delivered by CS and by VD, respectively. The results of Cox proportional hazards regression model demonstrated that children delivered by CS had significantly higher risks of ADHD, ASD, and intellectual disability than those delivered by VD after the confounding effects of maternal and child factors were controlled for.

Physical Activity, Gut Microbiota, and Genetic Background for Children and Adolescents with Autism Spectrum Disorder

It is estimated that one in 100 children worldwide has been diagnosed with autism spectrum disorder (ASD). Children with ASD frequently suffer from gut dysbiosis and gastrointestinal issues, findings which possibly play a role in the pathogenesis and/or severity of their condition. Physical activity may have a positive effect on the composition of the intestinal microbiota of healthy adults. However, the effect of exercise both on the gastrointestinal problems and intestinal microbiota (and thus possibly on ASD) itself in affected children is unknown. In terms of understanding the physiopathology and manifestations of ASD, analysis of the gut-brain axis holds some promise. Here, we discuss the physiopathology of ASD in terms of genetics and microbiota composition, and how physical activity may be a promising non-pharmaceutical approach to improve ASD-related symptoms.

Estimating the effect of cesarean delivery on long-term childhood health across two countries

Assessing the impact of cesarean delivery (CD) on long-term childhood outcomes is challenging as conducting a randomized controlled trial is rarely feasible and inferring it from observational data may be confounded. Utilizing data from electronic health records of 737,904 births, we defined and emulated a target trial to estimate the effect of CD on predefined long-term pediatric outcomes. Causal effects were estimated using pooled logistic regression and standardized survival curves, leveraging data breadth to account for potential confounders. Diverse sensitivity analyses were performed including replication of results in an external validation set from the UK including 625,044 births. Children born in CD had an increased risk to develop asthma (10-year risk differences (95% CI) 0.64% (0.31, 0.98)), an average treatment effect of 0.10 (0.07-0.12) on body mass index (BMI) z-scores at age 5 years old and 0.92 (0.68-1.14) on the number of respiratory infection events until 5 years of age. A positive 10-year risk difference was also observed for atopy (10-year risk differences (95% CI) 0.74% (-0.06, 1.52)) and allergy 0.47% (-0.32, 1.28)). Increased risk for these outcomes was also observed in the UK cohort. Our findings add to a growing body of evidence on the long-term effects of CD on pediatric morbidity, may assist in the decision to perform CD when not medically indicated and paves the way to future research on the mechanisms underlying these effects and intervention strategies targeting them.

Gut dysbiosis impairs hippocampal plasticity and behaviors by remodeling serum metabolome

Accumulating evidence suggests that gut microbiota as a critical mediator of gut-brain axis plays an important role in human health. Altered gut microbial profiles have been implicated in increasing the vulnerability of psychiatric disorders, such as autism, depression, and schizophrenia. However, the cellular and molecular mechanisms underlying the association remain unknown. Here, we modified the gut microbiome with antibiotics in newborn mice, and found that gut microbial alteration induced behavioral impairment by decreasing adult neurogenesis and long-term potentiation of synaptic transmission, and altering the gene expression profile in hippocampus. Reconstitution with normal gut flora produced therapeutic effects against both adult neurogenesis and behavioral deficits in the dysbiosis mice. Furthermore, our results show that circulating metabolites changes mediate the effect of gut dysbiosis on hippocampal plasticity and behavior outcomes. Elevating the serum 4-methylphenol, a small aromatic metabolite produced by gut bacteria, was found to induce autism spectrum disorder (ASD)-like behavior impairment and hippocampal dysfunction. Together our finding demonstrates that early-life gut dysbiosis and its correlated metabolites change contribute to hippocampal dysfunction and behavior impairment, hence highlight the potential microbiome-mediated therapies for treating psychiatric disorders.

Role of Gut Microbiome in Autism Spectrum Disorder and Its Therapeutic Regulation

Autism spectrum disorder (ASD) is a neurological disorder that affects normal brain development. The recent finding of the microbiota–gut–brain axis indicates the bidirectional connection between our gut and brain, demonstrating that gut microbiota can influence many neurological disorders such as autism. Most autistic patients suffer from gastrointestinal (GI) symptoms. Many studies have shown that early colonization, mode of delivery, and antibiotic usage significantly affect the gut microbiome and the onset of autism. Microbial fermentation of plant-based fiber can produce different types of short-chain fatty acid (SCFA) that may have a beneficial or detrimental effect on the gut and neurological development of autistic patients. Several comprehensive studies of the gut microbiome and microbiota–gut–brain axis help to understand the mechanism that leads to the onset of neurological disorders and find possible treatments for autism. This review integrates the findings of recent years on the gut microbiota and ASD association, mainly focusing on the characterization of specific microbiota that leads to ASD and addressing potential therapeutic interventions to restore a healthy balance of gut microbiome composition that can treat autism-associated symptoms.

Impact of caesarean delivery on children's autism-like behaviours: the mediation of exclusive breastfeeding

Background

The rate of autism spectrum disorder (ASD) has been rising worldwide, and therefore it is important to identify potential causes of ASD to facilitate early prevention. This study examined the role of breastfeeding and the association between caesarean delivery (CD) and children’s autism spectrum disorder.

Methods

The data were from the Ma’anshan birth cohort (MABC) in China, that was set up between May 2013 and September 2014. Women within 14 gestational weeks were recruited. The delivery mode was extracted from medical notes and infant feeding was obtained from questionnaire surveys. Autism-like behaviour was assessed using the Checklist for Autism in Toddlers (CHAT-23) when children were 18 months old, and 3 years of age. At 5 years of age, autism-like behaviour was assessed using the Clancy Autism Behavior Scale behavior. Structural equation models tested the mediation effects of breastfeeding between CD and children’s autism spectrum disorder.

Results

In all, 1520 (48.89%) women gave birth via CD, and 406 (13.86%) children were identified with autism-like behaviours at 18 months. Compared with women giving birth via vaginal delivery, those giving birth via CD were more likely to experience a higher proportion of delayed initiation of breastfeeding (p < 0.01), and delayed onset of lactogenesis (p < 0.01). CD was associated with a lower proportion of exclusive breastfeeding at 4 months after delivery (p = 0.02). Autism-like behaviour was less likely amongst infants with exclusively breastfeeding at 4 months than amongst those not exclusively breastfeeding at 4 months (p < 0.01). SEM indicated that women who gave birth by CD were more likely to stop exclusive breastfeeding in the first 4 months (standard estimations = − 0.04, p = 0.02), and those children who were not exclusively breastfed at 4 months were more likely to have autism-like behaviours (standard estimations = − 0.05, p < 0.01). The associations persisted at 3 years, but not at 5 years.

Conclusions

Exclusive breastfeeding at 4 months of age mediated the association between caesarean delivery and children’s autism-like behaviours.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13006-022-00493-6.

C-section increases cecal abundance of the archetypal bile acid and glucocorticoid modifying Lachnoclostridium [clostridium] scindens in mice

In humans and animal models, Cesarean section (C‐section) has been associated with alterations in the taxonomic structure of the gut microbiome. These changes in microbiota populations are hypothesized to impact immune, metabolic, and behavioral/neurologic systems and others. It is not clear if birth mode inherently changes the microbiome, or if C‐section effects are context‐specific and involve interactions with environmental and other factors. To address this and control for potential confounders, cecal microbiota from ~3 week old mice born by C‐section (n = 16) versus natural birth (n = 23) were compared under matched conditions for housing, cross‐fostering, diet, sex, and genetic strain. A total of 601 unique species were detected across all samples. Alpha diversity richness (i.e., how many species within sample; Chao1) and evenness/dominance (i.e., Shannon, Simpson, Inverse Simpson) metrics revealed no significant differences by birth mode. Beta diversity (i.e., differences between samples), as estimated with Bray‐Curtis dissimilarities and Aitchison distances (using log[x + 1]‐transformed counts), was also not significantly different (Permutational Multivariate ANOVA [PERMANOVA]). Only the abundance of Lachnoclostridium [Clostridium] scindens was found to differ using a combination of statistical methods (ALDEx2, DESeq2), being significantly higher in C‐section mice. This microbe has been implicated in secondary bile acid production and regulation of glucocorticoid metabolism to androgens. From our results and the extant literature we conclude that C‐section does not inherently lead to large‐scale shifts in gut microbiota populations, but birth mode could modulate select bacteria in a context‐specific manner: For example, involving factors associated with pre‐, peri‐, and postpartum environments, diet or host genetics.

Association of Early Life Prescriptions for Antibiotics and Acid Suppressants with Childhood Psychotropic Prescriptions

OBJECTIVE

To examine the association between antibiotic and acid suppressant prescriptions in the first 2 years of life and subsequent treatment for childhood psychiatric disorders.

STUDY DESIGN

This was a retrospective cohort study of children born between October 2001 and September 2012 in the Military Health System enrolled in TRICARE past age 2 years and within 35 days of birth, with an initial hospital stay <7 days, and without psychotropic agents dispensed during the first 2 years of life. Exposure was defined as a filled prescription for an antibiotic or acid suppressant before age 2 years, and the outcome was defined as a filled prescription for a psychotropic agent after age 2 years.

RESULTS

For the 804 920 patients (51% males and 49% female) composing the study population, the mean age at first psychotropic prescription was 6.8 years. A total of 24 176 children (3%) were prescribed a proton pump inhibitor (PPI), 79 243 (10%) were prescribed a histamine-2 receptor antagonist (H2RA), and 607 348 (76%) were prescribed an antibiotic during the first 2 years of life. The adjusted hazard ratio (aHR) of a psychotropic prescription was significantly increased in children prescribed any H2RA (1.79; 95% CI, 1.63-1.96), PPI (1.47; 95% CI, 1.26-1.71), or antibiotic (1.71; 95% CI, 1.59-1.84). The aHR of psychotropic prescriptions increased commensurately with each additional antibiotic class added and with each additional class of medication (H2RA, PPI, or antibiotics) prescribed.

CONCLUSIONS

Children prescribed antibiotic and acid suppressants in the first 2 years of life have a significant increase in future prescriptions for psychotropics, with a dose-related effect observed. This association represents a potential risk of early exposure to antibiotics and acid suppressants.

The function of gut microbiota in immune-related neurological disorders: a review

This review provides an overview of the importance of microbiota in the regulation of gut–brain communication in immune-related neurological disorders. The gastrointestinal (GI) tract hosts a diverse abundance of microbiota, referred to as gut microbiota. The gut microbiota plays a role in the maintenance of GI tract homeostasis and is likely to have multiple effects on brain development and function. The bidirectional communication between the gut microbiota and the brain is termed the microbiota–gut–brain axis. This communication between the intestine and the brain appears to affect human health and behavior, as certain animal studies have demonstrated the association between alterations in the gut microbiota and neurological disorders. Most insights about the microbiota–gut–brain axis come from germ-free animal models, which reveal the importance of gut microbiota in neural function. To date, many studies have observed the impact of the gut microbiota in patients with neurological disorders. Although many studies have investigated the microbiota–gut–brain axis, there are still limitations in translating this research to humans given the complexities of the relationship between the gut microbiota and the brain. In this review, we discuss emerging evidence of how the microbiota–gut–brain axis regulates brain development and function through biological networks, as well as the possible contribution of the microbiota–gut–brain axis in immune-related neurological disorders.

Attention-deficit hyperactivity disorder in children born to mothers with infertility: a population-based cohort study

STUDY QUESTION

Is the risk of attention-deficit hyperactivity disorder (ADHD) increased in children born to mothers with infertility, or after receipt of fertility treatment, compared to mothers with unassisted conception?

SUMMARY ANSWER

Infertility itself may be associated with ADHD in the offspring, which is not amplified by the use of fertility treatment.

WHAT IS KNOWN ALREADY

Infertility, and use of fertility treatment, is common. The long-term neurodevelopmental outcome of a child born to a mother with infertility, including the risk of ADHD, remains unclear.

STUDY DESIGN, SIZE, DURATION

This population-based cohort study comprised all singleton and multiple hospital births in Ontario, Canada, 2006–2014. Outcomes were assessed up to June 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Linked administrative datasets were used to capture all hospital births in Ontario, maternal health and pregnancy measures, fertility treatment and child outcomes. Included were all children born at ≥24 weeks gestation between 2006 and 2014, and who were alive at age 4 years. The main exposure was mode of conception, namely (i) unassisted conception (reference group), (ii) infertility without fertility treatment (history of an infertility consultation with a physician within 2 years prior to conception but no fertility treatment), (iii) ovulation induction (OI) or intrauterine insemination (IUI) and (iv) IVF or intracytoplasmic sperm injection (ICSI). The main outcome was a diagnosis of ADHD after age 4 years and assessed up to June 2020. Hazard ratios (HRs) were adjusted for maternal age, income quintile, rurality, immigration status, smoking, obesity, parity, any drug or alcohol use, maternal history of mental illness including ADHD, pre-pregnancy diabetes mellitus or chronic hypertension and infant sex. In addition, we performed pre-planned stratified analyses by mode of delivery (vaginal or caesarean delivery), infant sex, multiplicity (singleton or multiple), timing of birth (term or preterm <37 weeks) and neonatal adverse morbidity (absent or present).

MAIN RESULTS AND THE ROLE OF CHANCE

The study included 925 488 children born to 663 144 mothers, of whom 805 748 (87%) were from an unassisted conception, 94 206 (10.2%) followed infertility but no fertility treatment, 11 777 (1.3%) followed OI/IUI and 13 757 (1.5%) followed IVF/ICSI. Starting at age 4 years, children were followed for a median (interquartile range) of 6 (4–8) years. ADHD occurred among 7.0% of offspring in the unassisted conception group, 7.5% in the infertility without fertility treatment group, 6.8% in the OI/IUI group and 6.3% in the IVF/ICSI group. The incidence rate (per 1000 person-years) of ADHD was 12.0 among children in the unassisted conception group, 12.8 in the infertility without fertility treatment group, 12.9 in the OI/IUI group and 12.2 in the IVF/ICSI group. Relative to the unassisted conception group, the adjusted HR for ADHD was 1.19 (95% CI 1.16–1.22) in the infertility without fertility treatment group, 1.09 (95% CI 1.01–1.17) in the OI/IUI group and 1.12 (95% CI 1.04–1.20) in the IVF/ICSI group. In the stratified analyses, these patterns of risk for ADHD were largely preserved. An exception was seen in the sex-stratified analyses, wherein females had lower absolute rates of ADHD but relatively higher HRs compared with that seen among males.

LIMITATIONS, REASONS FOR CAUTION

Some mothers in the isolated infertility group may have received undocumented OI oral therapy, thereby leading to possible misclassification of their exposure status. Parenting behaviour, schooling and paternal mental health measures were not known, leading to potential residual confounding.

WIDER IMPLICATIONS OF THE FINDINGS

Infertility, even without treatment, is a modest risk factor for the development of ADHD in childhood. The reason underlying this finding warrants further study.

STUDY FUNDING/COMPETING INTEREST(s)

This study was made possible with funding from the Canadian Institutes of Health Research, Grant number PJT 165840. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

[Early prognostic of ASD: A challenge]

Autism Spectrum Disorders (ASD) are born in the womb generated by intrauterine genetic or environmental insult. ASD diagnostic is made at the age of 3-5 years in Europe and in the US. Relying on this, we have tested the hypothesis of identifying already at birth babies who might be diagnosed later with ASD, thereby facilitating an early use of psychoeducative techniques to attenuate the severity of the symptoms. Here, we discuss the various approaches that have been used to enable an early diagnosis. We have ourselves used an approach based on a "without a priori" machine learning analysis of all maternity biological and ultrasound data available in French maternities (around 116) in utero and after birth. This program made it possible to identify at birth almost all (96%) of babies who will be later neurotypical and around half of those who will be diagnosed with ASD. Some of the parameters allowing this identification were largely unexpected with no known links with ASD. This approach will enable an early identification of babies at risk, but also might be used to diagnose ASD later on, and perhaps could help to get a better understanding of the heterogeneity of ASD.

Animal Models for Assessing Impact of C-Section Delivery on Biological Systems

There has been a significant increase in Caesarean section (C-section) births worldwide over the past two decades and although it is can be a life-saving procedure, the enduring effects on host physiology are now undergoing further scrutiny. Indeed, epidemiological data have linked C-section birth with multiple immune, metabolic and neuropsychiatric diseases. Birth by C-section is known to alter the colonisation of the neonatal gut microbiota (with C-section delivered infants lacking vaginal microbiota associated with passing along the birth canal), which in turn can impact the development and maintenance of many important biological systems. Appropriate animal models are key to disentangling the role of missing microbes in brain health and disease in C-section births. In this review of preclinical studies, we interrogate the effects of C-section birth on the development (and maintenance) of several biological systems and we discuss the involvement of the gut microbiome on C-section-related alterations.

Early life environmental factors associated with autism spectrum disorder symptoms in children at age 2 years: A birth cohort study

LAY ABSTRACT

Mounting evidence indicates the contribution of early life environmental factors in autism spectrum disorder. We aim to report the prospective associations between early life environmental factors and autism spectrum disorder symptoms in children at the age of 2 years in a population-derived birth cohort, the Barwon Infant Study. Autism spectrum disorder symptoms at the age of 2 years strongly predicted autism spectrum disorder diagnosis by the age of 4 years (area under curve = 0.93; 95% CI (0.82, 1.00)). After adjusting for child's sex and age at the time of behavioural assessment, markers of socioeconomic disadvantage, such as lower household income and lone parental status; maternal health factors, including younger maternal age, maternal pre-pregnancy body mass index, higher gestational weight gain and prenatal maternal stress; maternal lifestyle factors, such as prenatal alcohol and environmental air pollutant exposures, including particulate matter < 2.5 μm at birth, child secondhand tobacco smoke at 12 months, dampness/mould and home heating with oil, kerosene or diesel heaters at 2 years postnatal. Lower socioeconomic indexes for area, later birth order, higher maternal prenatal depression and maternal smoking frequency had a dose-response relationship with autism spectrum disorder symptoms. Future studies on environmental factors and autism spectrum disorder should consider the reasons for the socioeconomic disparity and the combined impact of multiple environmental factors through common mechanistic pathways.

The association of cesarean section with overweight and neurodevelopment of Chinese children aged 1-5 months

OBJECTIVE

The purpose of this survey was to explore the association of delivery mode with overweight and neurodevelopment of Chinese infants aged 1-5 months.

MATERIALS AND METHODS

This study was based on a cross-sectional survey. Data for this study were obtained from the Children's Nutrition and Health System Survey in China which was conducted from 2019 to 2020. Characteristics of parents and children and the delivery mode were obtained using interview-administered questionnaires. Body mass index-for age z-score (BMI z) was calculated using World Health Organization (WHO) child growth standards. Children's neurodevelopment was assessed by a trained child health care physician using the Child Psychological Development Scale. The association of delivery mode with infant overweight was analyzed using a multivariable logistic regression model. We conducted a multivariable linear regression model to explore the relationship between delivery modes with neurodevelopment.

RESULTS

In total, the present analysis included 1,347 children aged 1-5 months, 35.61% were born via cesarean section, of which 15.21% were overweight. After adjustment for infant characteristics and parental factors, the cesarean section was significantly related with the likehood of being overweight [OR = 1.95; 95% confidence interval (CI): 1.27 to 2.98]. Children born via cesarean section had a 3.41-point decrease in gross motor development (β = -3.41; 95% CI: -5.77 to -1.05), a 3.65-point decrease in fine motor development (β = -3.65; 95% CI: -6.03 to -1.28), and a 2.96-point in language development (β = -2.96; 95% CI: -5.20 to -0.73), a 1.65-point in total development (β = -1.65; 95% CI: -3.17 to -0.14) compared with those who were vaginal birth.

CONCLUSION

In our study population, cesarean section was associated with overweight and neurodevelopment outcomes. The cesarean section might increase the likehood of infant overweight, and might decrease the developmental scores of gross motor, fine motor and language. Further studies should be conducted to verify the associations and explore the possible mechanisms.

Does cesarean delivery increase the occurrence of neurodevelopmental disorders in childhood?

OBJECTIVE

This study aimed to investigate whether cesarean delivery (CD) is associated with the occurrence of neurodevelopmental disorders (NDDs) at the age of 8 years.

METHODS

A total of 19 142 children were included from the Taiwan Birth Cohort Study (TBCS) database. Associations between modes of delivery or modalities of CD and NDDs were evaluated before and after controlling for gestational age (GA) and clinical condition at birth, children's characteristics, maternal socioeconomic status and maternal clinical condition at childbirth.

RESULTS

The odds ratio (OR) of occurrence of NDDs in children born via CD was 1.15 and the 95% confidence interval (CI) was 1.00-1.32. Emergency CD had a higher occurrence of NDDs (OR: 1.38; 95% CI: 1.16-1.65) compared with vaginal delivery. These associations were attenuated after controlling for children's and maternal characteristics and GA at birth. GA at birth had a significant reverse dose-effect on the occurrence of NDDs in children born via vaginal delivery and CD.

CONCLUSION

Modes of delivery and GA could influence the occurrence of NDDs in childhood. However, association of risk of NDDs and modes of delivery or modalities of CD might be modified by males, lower socioeconomic status and mothers with gestational diabetes mellitus.

Association of Neuraxial Labor Analgesia for Vaginal Childbirth With Risk of Autism Spectrum Disorder

IMPORTANCE

Recent studies have reported conflicting findings regarding a potential association between analgesia used during labor and autism spectrum disorder in the offspring.

OBJECTIVE

To evaluate whether neuraxial labor analgesia increases the risk of autism spectrum disorder in the offspring.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included mother-child dyads who underwent vaginal delivery and were exposed to neuraxial labor analgesia. Delivery data were collected from the Medicaid Analytic eXtract (2005-2014) for mothers with public insurance and the IBM Health MarketScan Research Database (2005-2015) for mothers with private insurance. Data analysis was conducted from January to October 2021.

EXPOSURES

Presence of a procedure code indicating neuraxial labor analgesia.

MAIN OUTCOMES AND MEASURES

Children with autism spectrum disorder, identified using a validated algorithm (positive predictive value: 94% [95% CI, 83%-99%]). Cumulative incidence curves stratified by exposure were assessed using Kaplan-Meier analyses. Hazard ratios were estimated through Cox proportional hazards regression, using propensity-score fine stratification for confounding control. Estimates from both insurance cohorts were combined through fixed-effects meta-analysis. Subsequently, results from these analyses were combined with existing published studies.

RESULTS

The cohort of mother-child dyads with public insurance consisted of 910 696 deliveries (mean [SD] maternal age, 24.3 [5.7] years; 286 025 [31.4%] Black mothers; 374 282 [41.1%] White mothers), with 484 752 (53.2%) being exposed to neuraxial labor analgesia. The cohort of mother-child dyads with private insurance included 696 883 deliveries (mean [SD] maternal age, 31.0 [4.5] years; race and ethnicity data not available), with 513 347 (73.7%) being exposed. Cumulative incidence of autism spectrum disorder by 10 years of age was 1.93% (95% CI, 1.73%-2.13%) among children in the exposed group vs 1.64% (95% CI, 1.51%-1.76%) among children in the unexposed group in the publicly insured cohort. Respective numbers were 1.33% (95% CI, 1.19%-1.46%) and 1.19% (95% CI, 0.99%-1.38%) in the privately insured cohort. Adjusting for potential confounders and pooling across both cohorts resulted in a hazard ratio of 1.08 (95% CI, 1.02-1.15). Results were consistent when additionally adjusting for empirically identified variables through high-dimensional propensity score analyses (pooled hazard ratio, 1.07; 95% CI, 1.00-1.14) or expanding the cohorts to include cesarean deliveries and assisted vaginal deliveries (pooled hazard ratio, 1.07; 95% CI, 1.03-1.12). Meta-analysis of this study and recently published observational studies yielded similar findings with a pooled hazard ratio of 1.10 (95% CI, 1.06-1.13).

CONCLUSIONS AND RELEVANCE

Although a small increase in risk cannot be ruled out, the combined evidence from observational studies does not support the notion that neuraxial labor analgesia is associated with an increased risk of autism spectrum disorder.

Delivery Mode and Child Development at 20 Months of Age and 7 Years of Age in the Republic of Seychelles

OBJECTIVE

To determine if cesarean delivery is adversely associated with child neurodevelopment as measured at 20 months and 7 years.

METHODS

In a prospective cohort study (n = 1328) in the Republic of Seychelles, we examined the association between mode of delivery and 22 measures of child neurodevelopment spanning multiple domains: cognition, executive and psychomotor function, language development, behavior, scholastic achievement, and social communication. Using multivariable linear regression, we evaluated the relationship between delivery mode (Cesarean/vaginal delivery) and each developmental outcome, while controlling for relevant covariates including child sex and age, maternal age, maternal IQ, whether both parents lived with the child, and Hollingshead socioeconomic status.

RESULTS

At 20 months, children born via cesarean delivery had slightly higher scores (β = 0.11, 95% confidence interval: 0.00, 0.21) on the Infant Behavior Questionnaire-Revised Positive Affectivity/Surgency subtest, a measure of infant temperament, as compared to vaginal delivery. Delivery mode was not associated with any of the 7-year developmental outcomes.

CONCLUSIONS FOR PRACTICE

Our study does not support the notion that cesarean delivery is associated with child neurodevelopmental outcomes.

Brief Report: Pregnancy, Birth and Infant Feeding Practices: A Survey-Based Investigation into Risk Factors for Autism Spectrum Disorder

A succession of interconnected environmental factors is believed to contribute substantially to the development of autism spectrum disorder (ASD). This exploratory study therefore aims to identify potential risk factors for ASD that are associated with pregnancy, birth and infant feeding. Demographic and health-related data on children aged 3-13 years (N = 4306) was collected through an online survey completed by biological mothers. A fitted logistic regression model identified advanced maternal age, prenatal bleeding, pre-eclampsia, perinatal pethidine usage, foetal distress before birth and male sex of child as associated with an increased risk of ASD, whereas longer gestational duration demonstrated a protective effect. These findings highlight potential risk factors and predictor interrelationships which may contribute to overall ASD risk.

Cesarean birth elicits long-term effects on vasopressin and oxytocin neurons in the hypothalamic paraventricular nucleus of mice

Birth is an extraordinary event for placental mammals and occurs at a time when key developmental processes are shaping the brain. Remarkably, little is known about the contributions of birth to brain development and whether birth mode (vaginal vs. Cesarean) alters neurodevelopmental trajectories. We previously reported that Cesarean birth reduces vasopressin (VP) neuron number in the hypothalamic paraventricular nucleus (PVN) of mice at weaning. In this study, we investigated whether this effect extends to adulthood and whether birth mode affects oxytocin (OT) neurons, which are another prominent population in the PVN. We found that Cesarean-born adults had fewer VP neurons in the PVN, specifically in magnocellular regions. Interestingly, these regions also had more dying cells following a Cesarean birth, suggesting that cell death may be the underlying mechanism. The PVN of Cesarean-born adults also had smaller VP neuron somas and reduced VP efferent projections. Additionally, Cesarean-born mice showed fewer and smaller OT neurons in the PVN, but these effects were less robust than for VP neurons. We also examined VP and OT neuron number in the supraoptic and suprachiasmatic nuclei but found no effect of birth mode in these regions. Thus, Cesarean birth causes long-term effects on the VP and, to a lesser extent, OT systems in the PVN, suggesting that this region is particularly sensitive to the effects of birth mode. Our findings may help explain the social deficits reported for Cesarean-born mice, and are also of clinical significance given the widespread practice of Cesarean births across the world.

Peripartum Antibiotics Exposure and the Risk of Autoimmune and Autism Disorders in the Offspring

Background As the use of antibiotics during the peripartum period increases, the incidence of autoimmune disorders and autism spectrum disorders (ASDs) is also increasing. In this study, we aim to assess if antibiotic exposure during the peripartum period affects the incidence of autoimmune diseases and ASD in the offspring. Methods We identified children (< 18 years of age) born in Olmsted County from January 1, 2003 through December 31, 2012. Offspring with celiac disease (CD), inflammatory bowel disease (IBD), or ASD diagnoses were matched to two controls on birth date, index date, mother's age at delivery, and sex. Data from the mother's medical records were retrieved to determine peripartum antibiotics use. Results A total of 242 cases and 484 matched controls were included in this study. Median age at the last follow-up was 11.3 years (range: 0.5-14.9), 73% were males in both groups. Odds of CD diagnosis was not statistically different between vaginal delivery with antibiotics compared with vaginal delivery with no antibiotics (odds ratio [OR] = 0.76, 95% confidence interval [CI]: 0.32-1.85), similarly in IBD (OR = 2.41, 95% CI: 0.53-10.98) and ASD (OR = 1.00, 95% CI:0.55-1.79). Preeclampsia or eclampsia was associated with offspring CD (OR = 3.20, 95% CI: 1.05-9.78). Smoking history and diabetes mellitus were associated with offspring ASD (OR = 1.84, 95% CI: 1.22-2.77 and OR = 2.01, 95% CI: 1.03-3.91, respectively). Conclusion In this cohort, we found no statistically significant association between peripartum antibiotics exposure and the development of CD, IBD, or ASD.

Role of Maternal Microbiota and Nutrition in Early-Life Neurodevelopmental Disorders

The rise in the prevalence of obesity and other related metabolic diseases has been paralleled by an increase in the frequency of neurodevelopmental problems, which has raised the likelihood of a link between these two phenomena. In this scenario, maternal microbiota is a possible linking mechanistic pathway. According to the "Developmental Origins of Health and Disease" paradigm, environmental exposures (in utero and early life) can permanently alter the body's structure, physiology, and metabolism, increasing illness risk and/or speeding up disease progression in offspring, adults, and even generations. Nutritional exposure during early developmental stages may induce susceptibility to the later development of human diseases via interactions in the microbiome, including alterations in brain function and behavior of offspring, as explained by the gut-brain axis theory. This review provides an overview of the implications of maternal nutrition on neurodevelopmental disorders and the establishment and maturation of gut microbiota in the offspring.

Association of Attention Deficit/Hyperactivity Disorder With Events Occurring During Pregnancy and Perinatal Period

Background: The relationship of events occurring during pregnancy and perinatal period with attention deficit/hyperactivity disorder (ADHD) is not clear. Thus, the focus of the current study was to examine the effects of events occurring during pregnancy and perinatal period on ADHD.

Methods: A two-phase cross-sectional study was performed across 13 schools in Changsha and Yiyang cities from March to December, 2014. We preliminarily screened all students using CBCL and established the diagnosis using Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). A total of 3,418 questionnaires were effectively completed in this study.

Results: History of threatened abortion (TA) [odds ratio (OR): 1.707 (1.201–2.426)] (vs. No-TA) and neonatal asphyxia (NA) [OR: 2.497(1.225–5.09)] (vs. health) showed a positive association with ADHD. On subgroup analysis, TA [OR: 2.216 (1.458–3.369)] (vs. No-TA) was a risk factor for ADHD without comorbidity; instrumental delivery [OR: 2.748 (1.057–7.142)] (vs. natural birth) and NA [OR: 2.789 (1.222–6.361)] (vs. health) were risk factors for ADHD in the subgroup of ADHD with comorbidity; TA (vs. no-TA) and NA (vs. health) were risk factors for ADHD among male students [ORs: 2.232 (1.439–3.462) and 2.808 (1.115–7.068), respectively], while low birth weight (LBW) (vs. normal birth weight) was a risk factor [OR: 2.054 (1.063–3.967)] for ADHD among female students.

Conclusion: TA was a risk factor for ADHD in the absence of comorbid conditions; instrumental delivery and NA were risk factors for ADHD in the subgroup of ADHD with comorbidity; TA and NA were risk factors for ADHD among male students. LBW was a risk factor for ADHD among female students.

Association Between Exposure of Children to General Anesthesia and Autism Spectrum Disorder

This study tested the hypothesis that exposure of children prior to their third birthday to procedures requiring general anesthesia is associated with an increased incidence of autism spectrum disorder (ASD) in later life. This study employed a nested, 1:2 matched-case control study design using ASD cases identified in a population-based birth cohort of children born in Olmsted County, MN from 1976 to 2000. Matching variables included sex, date of birth, and mother's age in conditional logistic regression including 499 ASD cases and 998 controls. After adjusting for birth weight and health status, there was no significant association between exposure and ASD (OR 1.27 [95% CI 0.92-1.76]), indicating that general anesthesia is not associated with an increased risk of ASD.