Association of Cesarean Delivery With Risk of Neurodevelopmental and Psychiatric Disorders in the Offspring: A Systematic Review and Meta-analysis

Prenatal and early childhood infections requiring hospitalization and risk of neurodevelopmental disorders in offspring: a population-based birth cohort study in Taiwan

In utero and early childhood infections have been associated with an increased risk of neurodevelopmental disorders; however, the observed associations may be confounded by familial predispositions. This study examined the neurodevelopmental disorders attributable to maternal infections during pregnancy and early childhood infections during the first year of life, including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), tic disorders, and mental retardation (MR). We performed population and sibling comparison analyses to account for unmeasured familial confounding factors. We conducted a register-based cohort study with 2,885,662 individuals (comprising 1,864,660 full siblings) born in Taiwan between 2001 and 2018 and followed up until 2021. We employed Cox regression analysis to assess the association between in utero and early childhood infections requiring hospitalization and the subsequent risk of neurodevelopmental disorders. In the population analyses, an offspring exposed to maternal infection had an increased risk for ASD (hazard ratio (HR) = 1.19, 95% confidence interval (CI): 1.13-1.26), ADHD (HR = 1.14, 95% CI: 1.11-1.18), and MR (HR = 1.21, 95% CI: 1.13-1.30). These associations attenuated toward null in the sibling analyses. Individuals exposed to early childhood infection had an increased risk for ASD (HR = 1.13, 95% CI: 1.10-1.16), ADHD (HR = 1.16, 95% CI: 1.15-1.18), tic disorders (HR = 1.12, 95% CI: 1.09-1.15), and MR (HR = 1.64, 95% CI: 1.60-1.69) in the population analyses; these associations were also significant for ASD (HR = 1.14, 95% CI: 1.07-1.21) and MR (HR = 1.52, 95% CI: 1.44-1.62) in the sibling analyses. The association between maternal infection during pregnancy and offspring neurodevelopmental risk is largely due to familial confounding factors. Conversely, infection in early childhood may be attributable to it being a sensitive period and may play a role in the subsequent risk of ASD and MR.

Gut microbes: Therapeutic Target for neuropsychiatric disorders

Neuropsychiatric diseases encompass a range of mental and neurological disorders that have a significant and far-reaching effect on an individual's quality of life. These conditions affect not only the mental status but also the physical well-being of individuals, which leads to weakened immune systems and other diseases. Emerging research underscores a significant connection between the gut microbiome and neuropsychiatric diseases, suggesting that microbial communities within the gastrointestinal tract may influence brain function and mental health. Gut dysbiosis is caused by various factors, including stress, diet, inappropriate usage of antibiotics, infections, and so on, all of which can disrupt numerous pathways, resulting in abnormal neurotransmitter signaling, inflammation, and impaired brain function. Similarly, various neuropsychiatric diseases can disrupt the specific microbiome in the gut, leading to gut dysbiosis, often impairing memory and cognitive function. The growing evidence supporting the role of gut dysbiosis in neuropsychiatric disorders has opened up new avenues for therapeutic interventions. Modulating the gut microbiome through strategies such as probiotics, prebiotics, or fecal microbiota transplantation has shown promising results in various studies of neuropsychiatric disorders. However, further research is needed to fully elucidate the mechanisms involved in gut dysbiosis-associated brain changes to develop effective and personalized treatment strategies for neuropsychiatric diseases.

Health outcomes up to 5 years in children born as a second child after a previous caesarean section in a first pregnancy: a Swedish population-based register study between 1999 and 2015

OBJECTIVE

To explore health outcomes up to 5 years of age, according to mode of birth, in a large cohort of Swedish children who were born as a second child to women who had a caesarean section (CS) in their first pregnancy.

DESIGN

Retrospective population-based register study.

POPULATION

All children (n=94 498) who were born as a second child (or children in cases of twins or higher-order multiple births) during 1999-2015 in Sweden in women who had a CS first birth. The children were followed up to 5 years of age. For inclusion, both births must have occurred in Sweden.

METHODS

A nationwide cohort study using follow-up data up to 5 years of age. Maternal factors, including age, smoking, diabetes, obesity (body mass index ≥30), mental illness, pre-eclampsia, education, income, country of birth and the neonatal factors of being a singleton and prematurity (up to week 36+6) were adjusted for in regression models.

MAIN OUTCOME MEASURES

Developmental problems, asthma, allergy, hospital care and death within 5 years of age.

RESULTS

A total of 94 498 children were included in the study. Risk for developmental problems, asthma and allergy was increased after repeat CS but not after vaginal birth. The need for hospital care was increased in all other birth modes compared with spontaneous vaginal birth. The risk of death within 5 years increased after instrumental vaginal birth and emergency repeat CS.

CONCLUSIONS

All repeat CS compared with spontaneous vaginal birth was related to increased risks for developmental problems, asthma, allergy and hospital stay, and emergency repeat CS was associated with an increased risk of death within 5 years. The results of the present study support vaginal birth as the optimal mode of birth after previous CS for longer-term child health outcomes.

Mode of delivery among preterm twins and offspring health, a retrospective cohort study

Although cesarean delivery (CD) has been linked to long-term health risks in singleton infants, the impact of delivery mode on long-term health outcomes in preterm twins remains underexplored. A retrospective cohort study was conducted at a tertiary medical center in Israel from 1991 to 2021, comparing preterm twins vaginally delivered (VD) versus cesarean section, excluding cases with congenital malformations or perinatal deaths. Kaplan-Meier survival curves were used to compare the cumulative incidence, and Cox proportional hazards models were applied to adjust for potential confounders. Four thousand twenty-eight preterm twin offspring were included, with 1703 (42%) VD and 2325 (58%) by CD. Preterm twins delivered by CD had a higher incidence of respiratory morbidities (42% vs. 35% in the VD group, p < 0.001), with an adjusted Hazard Ratio (aHR) of 1.15 (95%CI 1.02-1.30). CD was associated with an increased incidence of neurologic morbidities (22% vs. 17% in the VD group, p < 0.001), with an aHR of 1.16 (95%CI 1.02-1.36). CD was associated with a higher incidence of infectious morbidities (69% vs. 62%, p < 0.001), with an aHR of 1.10 (95%CI 1.01-1.21). Gastrointestinal morbidities were more pronounced in the CD group (29% vs. 25%, p < 0.001), but the multivariable analysis did not reach significance (aHR = 1.10, 95%CI 0.95-1.27). Sub-analyses of elective-uncomplicated deliveries showed consistent results for most morbidities.

CONCLUSIONS

Cesarean delivery in preterm twins is associated with long-term respiratory, neurologic, infectious and gastrointestinal morbidities of the offspring. The findings suggest the potential benefits of vaginal over cesarean deliveries regarding offspring long-term health complications.

WHAT IS KNOWN

• Studies on singleton births show that cesarean delivery may increase respiratory, infectious, neurological and gastrointestinal outcomes remains inconsistent across term and preterm deliveries. • Cesarean delivery rates remain high despite recommendations to reduce their frequency, yet data on the association between cesarean delivery and morbidity among twins, particularly in small for gestational age twins, is limited.

WHAT IS NEW

• This is the first large-scale study demonstrating that cesarean delivery in preterm twins increases the odds of respiratory, neurologic, infectious and gastrointestinal long-term morbidities up to age 18. • The higher rates of respiratory, neurologic, infectious, and gastrointestinal complications persist even in uncomplicated cesarean deliveries.

Cesarean Section, Childhood Health, and Schooling: Quasi-Experimental Evidence From Denmark, Norway and Sweden

Despite being one of the most common surgical procedures in industrialized countries, there is limited causal evidence on the long-term consequences of Cesarean section (CS). We study the impacts of CS on health during ages 1-12 years and human capital outcomes at age 16 years, using exogenous variation in the probability of receiving a CS for breech births at term-a group with high CS risk. We use administrative data from Denmark, Norway, and Sweden to show that preventing complicated vaginal births benefits health at birth and reduces the number of all-cause hospital nights during childhood. Our findings for childhood diagnoses for asthma, allergies, diabetes mellitus type 1, and school outcomes are imprecise and do thus not lend strong support for prominent hypotheses on CS causing long-term immune dysfunction disorders and, thereby, worse human capital outcomes.

Early antibiotic exposure and risk of psychiatric and neurocognitive outcomes: systematic review and meta-analysis

BACKGROUND

The prenatal and early-life periods pose a crucial neurodevelopmental window whereby disruptions to the intestinal microbiota and the developing brain may have adverse impacts. As antibiotics affect the human intestinal microbiome, it follows that early-life antibiotic exposure may be associated with later-life psychiatric or neurocognitive outcomes.

AIMS

To explore the association between early-life (in utero and early childhood (age 0-2 years)) antibiotic exposure and the subsequent risk of psychiatric and neurocognitive outcomes.

METHOD

A search was conducted using Medline, PsychINFO and Excerpta Medica databases on 20 November 2023. Risk of bias was assessed using the Newcastle-Ottawa scale, and certainty was assessed using the grading of recommendations, assessment, development and evaluation (GRADE) certainty assessment.

RESULTS

Thirty studies were included (n = 7 047 853 participants). Associations were observed between in utero antibiotic exposure and later development of autism spectrum disorder (ASD) (odds ratio 1.09, 95% CI: 1.02-1.16) and attention-deficit hyperactivity disorder (ADHD) (odds ratio 1.19, 95% CI: 1.11-1.27) and early-childhood exposure and later development of ASD (odds ratio 1.19, 95% CI: 1.01-1.40), ADHD (odds ratio 1.33, 95% CI: 1.20-1.48) and major depressive disorder (MDD) (odds ratio 1.29, 95% CI: 1.04-1.60). However, studies that used sibling control groups showed no significant association between early-life exposure and ASD or ADHD. No studies in MDD used sibling controls. Using the GRADE certainty assessment, all meta-analyses but one were rated very low certainty, largely owing to methodological and statistical heterogeneity.

CONCLUSIONS

While there was weak evidence for associations between antibiotic use in early-life and later neurodevelopmental outcomes, these were attenuated in sibling-controlled subgroup analyses. Thus, associations may be explained by genetic and familial confounding, and studies failing to utilise sibling-control groups must be interpreted with caution. PROSPERO ID: CRD42022304128.

Association between some environmental risk factors and attention-deficit hyperactivity disorder among children in Egypt: a case-control study

BACKGROUND

Attention-Deficit Hyperactivity Disorder (ADHD) is a complex disease that negatively impacts the social and academic/occupational activities of children and is more common in boys than in girls.

METHODS

This case-control study aimed to assess the association between some environmental risk factors and ADHD among children in Alexandria, Egypt. It was carried out at the outpatient clinics of El Shatby Pediatric University Hospital in Alexandria, Egypt, with 252 children (126 cases and 126 controls). Hair samples were collected for analysis of lead and manganese levels using Atomic Absorption Spectrophotometer. A pre-designed interview questionnaire was used to determine the important environmental risk factors that may be related to ADHD.

RESULTS

Children from parents with low levels of education, living in crowded houses, and occupational exposure to chemical agents were found to be risk factors for ADHD. The mean ± SD hair lead level in ADHD children was 2.58 ± 1.95, while in controls was 1.87 ± 0.92, with a statistically significant difference (p < 0.001). The mean ± SD hair manganese level in ADHD children was 2.10 ± 1.54, while in controls was 1.11 ± 0.69, with a statistically significant difference (p < 0.001). The logistic regression model revealed that six factors had a significant association with ADHD: using of newspapers to wrap food 3 or more times a week (adjusted odds ratio (AOR) = 105.11, 95% CI: 11.18-988.26), daily TV watching by child for more than 5 h (AOR = 63.96, 95% CI: 2.56-1601.32), child's eating commercially packed noodles 3 times or more per week (AOR = 57.73, 95% CI: 3.77-593.93), using unpackaged flour in cooking (AOR = 44.47, 95% CI: 1.83-629.80), eating sweets daily by child (AOR = 6.82, 95% CI: 1.23-37.94), and lastly elevated hair Manganese level (AOR = 3.57, 95% CI: 1.24-10.29).

CONCLUSIONS

ADHD is a multi-factorial disorder, where many environmental risk factors contribute to its development. Future efforts to determine the best preventive strategy in Egypt must be based on a better knowledge of the role of environmental risk factors in the etiology of the disorder. Eliminating non-essential uses of lead and providing public education regarding the importance of safe disposal of lead-acid batteries and computers are necessary.

Functional Connectivity to the Amygdala in the Neonate Is Impacted by the Maternal Anxiety Level During Pregnancy

BACKGROUND AND PURPOSE

Anxiety during pregnancy is common, and exposure to heightened anxiety during pregnancy may influence children's brain development and functioning. However, it is unclear if exposure to low levels of anxiety in utero would also impact the developing brain. The current prospective and longitudinal study included 40 healthy pregnant women without pregnancy complications or previous diagnosis of anxiety disorders.

METHODS

Pregnant women's anxiety symptoms were measured at 12, 24, and 36 weeks of gestation. Their healthy, full-term offspring underwent a brain MRI scan without sedation, including resting-state functional MRI, at 2 weeks postnatal age. The associations between neonatal brain cortical functional connectivity originating from the amygdala and maternal prenatal anxiety symptom scores were examined using correlational analyses.

RESULTS

Significant correlations were identified after controlling for child sex, postmenstrual age at MRI, and mother's depression symptom scores. Higher maternal anxiety during pregnancy was related to alterations in offspring's functional connectivity between the amygdala and other brain regions involved in fear learning. Specifically, higher maternal prenatal anxiety during the first trimester of pregnancy was associated with lower connectivity between the amygdala and fusiform gyrus and higher connectivity between the amygdala and thalamus. Higher maternal prenatal anxiety during the third trimester was also associated with lower connectivity between the amygdala and fusiform gyrus.

CONCLUSIONS

The findings from this study indicate that exposure to low levels of anxiety in utero may also impact offspring brain development and functioning, particularly brain regions that are important for threat detection.

Association of preterm birth and birth size status with neurodevelopmental and psychiatric disorders in spontaneous births

Preterm birth (PTB) or small birth size are risk factors for certain neurodevelopmental disorders. The magnitude of these associations in spontaneous births, and of associations for combined PTB and birth size status on neurodevelopmental and psychiatric disorders is unexplored. We investigated whether PTB and small/large for gestational age (SGA/LGA), separately or combined, in spontaneous births, are associated with a wide spectrum of neurodevelopmental and psychiatric disorders. In this population-based registry cohort study, all singleton spontaneous births in Finland from 1996 to 2014 were followed until 2018 (n = 819 764). We show that PTB across gestational ages, and SGA, were associated with higher risks for anxiety disorders, intellectual disabilities, specific developmental disorders (SDD), autism spectrum disorders (ASD), attention-deficit/hyperactivity disorders (ADHD) and other emotional and behavioural disorders (F98). Most of these associations were not attributed to familial factors. Larger effect sizes were observed with lower gestational ages. Extremely PTB was associated at highest risks with intellectual disabilities (HR, 10.70 [95%CI, 8.69-13.17]) and SDD (HR, 8.91 [95%CI, 8.18-9.71]). Moreover, very preterm birth combined with SGA was associated with a higher risk for SDD (HR, 7.55 [95%CI, 6.61-8.62]) than that of very preterm or SGA birth alone. Conversely, LGA birth lowered the risk for SDD and other emotional and behavioural disorders among individuals born very preterm. In conclusion, PTB along with SGA is associated with higher risks for SDD than one exposure alone, whereas LGA lowers the risks for SDD and other emotional and behavioural disorders in individuals born spontaneously.

Screen time and childhood attention deficit hyperactivity disorder: a meta-analysis

OBJECTIVES

The association between screen time and attention deficit hyperactivity disorder (ADHD) has been controversial. This study sheds light on the contentious correlation between screen time and ADHD.

CONTENT

Until August 2022, electronic searches of the PubMed, Embase, and Web of Science databases were carried out. The combined effect value odds ratios (OR) and 95 % confidence interval (95 % CI) were calculated for the meta-analysis using Stata 12.0. There were 81,234 children in the nine studies that made up this meta-analysis which included 28,997 children with ADHD and 52,237 healthy controls. When compared with the screen time <2  h/d, the OR (95 % CI) value of screen time and ADHD in the screen time ≥2 h/d group was 1.51 (1.20-1.90).

SUMMARY AND OUTLOOK

Based on the current meta-analysis results, our study found a positive correlation between screen time and the risk of ADHD. Excessive screen exposure may significantly contribute to the development of ADHD in children. Therefore, it is necessary to reduce screen time per day in children to prevent the occurrence of ADHD.

Associations of paternal age with offspring under-five mortality and perinatal outcomes: a cohort study using claims data in Taiwan

Background

The causal relationship between advanced paternal age and offspring health is unclear, owing to familial confounders. This study examined the association of paternal age with offspring's under-five mortality and perinatal outcomes, using sibling comparison analyses to account for familial confounding factors.

Methods

A nationwide birth cohort study was designed based on Taiwan's single-payer compulsory National Health Insurance programme. Individuals born between 2001 and 2015 were included, resulting in 2454 104 live-born singletons. Among them, 1513 222 individuals had full sibling(s) who were included in the sibling-comparison analyses. Logistic regression analyses were used to evaluate the main study cohort whereas conditional logistic regressions were used in the sibling-comparison analyses.

Results

In the main cohort, paternal age categories showed a U-shaped relationship with offspring's under-five mortality in the crude analysis, which attenuated towards the null hypothesis after accounting for the measured potential confounders. There was an increased risk of premature birth (gestational age <37 weeks), low birth weight (<2500 g), large for gestational age (90th percentile) and low 5 min Apgar Score (<7) in individuals with a paternal age of >35 years. Sibling-comparison analyses that accounted for unmeasured familial time-invariant confounders showed that younger siblings with older paternal age had a lower risk of under-five mortality, low birth weight, small for gestational age (10th percentile), congenital defects and low 5 min Apgar Score, and a higher risk of premature birth and large for gestational age.

Conclusions

Children with older fathers had lower risks of under-five mortality, low birth weight, small for gestational age, congenital defects and low 5 min Apgar Score.

Cesarean delivery and its determining factors: A hospital-based study in Jashore District, Bangladesh

Background

The rising prevalence of cesarean deliveries (CD) is a major public health problem worldwide, especially in Bangladesh. This study aims to investigate the prevalence and factors associated with cesarean deliveries in the Jashore district of Bangladesh.

Study design

This cross-sectional study, conducted from December 2022 to February 2023 in Jashore district, Bangladesh, involved face-to-face interviews with 662 mothers during hospital visits.

Methods

A pretested, structured, and validated questionnaire was employed to gather information on socioeconomic characteristics, obstetric history, maternal healthcare utilization, and factors influencing the choice of delivery method. Multinomial logistic regression models were employed to assess and predict determining factors influencing cesarean delivery.

Results

The study revealed a high cesarean delivery (CD) prevalence of 70.5 %, exceeding the WHO-recommended threshold. Key socioeconomic factors associated with increased CD rates included rural residence, younger maternal age (15-20 years), nuclear family structure, and husbands in business. Additionally, private hospital deliveries, a history of previous CD, maternal self-preference, and doctor's influence were significant predictors of CD. The majority of participants believed CD enhances maternal safety (74.6 %) and alleviates pain (74.8 %).

Conclusion

The high rate of cesarean deliveries in Jashore highlights the need for public health interventions that improve access to quality maternal care and promote evidence-based decision-making. Reducing unnecessary cesarean procedures, particularly in private hospitals, and enhancing patient education can significantly improve maternal and neonatal health outcomes.

Modified neuroimmune processes and emotional behaviour in weaned and late adolescent male and female mice born via caesarean section

Elective and emergency Caesarean section (C-section) procedures are on the rise, exceeding the recommended guidelines by the World Health Organization. Higher morbidities and long-term health conditions are correlated to C-section deliveries, including neurodevelopmental disorders. During C-section delivery, newborns are not exposed to the vaginal commensal flora, which impedes the early establishment of the gut microbiota. The latter is essential for adequate neuro-immune processes to take place during infancy. In this study, we used a validated model of mice born by C-section (CSD), which mimics clinical observations of dysregulated gut microbiota. Animals were either born naturally or by CSD, before being adopted by dams who underwent delivery within the 12 preceding hours. Behavioural analyses were conducted at post-natal day (PND) 21 and 55. Our results indicate that animals born by C-section present significantly higher body weight in late (PND40-P53) but not early adolescence (PND21-P27), compared to animals born by vaginal delivery (VD). Male animals delivered by C-section presented significantly lower exploration time of the novel arm in the Y Maze test at PND55. However, at PND21, abnormal social interaction was witnessed in male and female animals born by CSD, with significantly decreased time spent interacting during the social interaction test. At both PND21 and PND55, animals from both sexes born by C-section presented significantly decreased time spent in the open arm of the Elevated Plus Maze test, compared to control animals. We then measured the expression of genes associated to neuroimmune interactions (microglia phenotype), inflammatory mediators and lipids in several brain structures of VD and CSD mice at PND21 and PND55. At weaning, animals born by CSD presented altered microglia, inflammatory and lipid metabolism signatures, with increased expression of Cd36, Csf1r and Tnfα in different brain regions of males, but not in females. At PND64, Csf1r, Tmem119 as well as C3ar1 were significantly increased in males born by C-section, but not in females. In males born by vaginal delivery, the expression of Cd36 at PND64 was correlated to anxiety at PND55, whilst a correlation between the expression of Clec7a and the number of head dippings in the elevated plus maze was also noted in males born by CSD. Altogether, our study shows altered emotional behaviour in animals delivered by CSD, which is likely explained by underlying neuro-inflammatory processes in different brain regions. Our work further supports the long-term consequences of CSD on brain health.

Cesarean delivery and blood DNA methylation at birth and childhood: Meta-analysis in the Pregnancy and Childhood Epigenetics Consortium

Children born via cesarean delivery have a higher risk of metabolic, immunological, and neurodevelopmental disorders compared to those born via vaginal delivery, although mechanisms remain unclear. We conducted a meta-analysis of epigenome-wide association studies to examine the associations between delivery mode and blood DNA methylation at birth and its persistence in early childhood. Participants were from 19 pregnancy cohorts (9833 term newborns) and 6 pediatric cohorts (2429 children aged 6 to 10 years). We identified six CpGs in cord blood associated with cesarean delivery (effect size range: 0.4 to 0.7%, P < 1.0 × 10-7): MAP2K2 (cg19423175), LIM2 (cg01500140), CNP (cg13917614), BLM (cg18247172), RASA3 (cg22348356), and RUNX3 (cg20674490), independent of cell proportions and other confounders. In childhood, none of these CpGs were associated with cesarean delivery, and no additional CpGs were identified. Delivery mode was associated with cell proportions at birth but not in childhood. Further research is needed to elucidate cesarean delivery's molecular influence on offspring health.

The Significance of Plant Nutrition in the Creation of the Intestinal Microbiota-Prevention of Chronic Diseases: A Narrative Review

Dysbiosis of the gastrointestinal tract is the most common cause of disease in childhood and adulthood. The formation of the intestinal microbiome begins in utero, and composition modification during life depends mainly on various genetic, nutritional, and environmental factors. The main cause of intestinal dysbiosis is improper nutrition due to a short period of breastfeeding, insufficient intake of fresh fruits and vegetables, and/or consumption of a large amount of processed food. The benefits of a diet based on grains, legumes, fruits, and vegetables are reflected in reducing the risk of cancer, cardiovascular diseases, myocardial infarction, stroke, rheumatoid arthritis, high blood pressure, asthma, allergies, and kidney stones. Anaerobic fermentation of fibers produces short-chain fatty acids (SCFA) that have an anti-inflammatory role and great importance in shaping the intestinal microbiota. Factors associated with high fiber in a plant-based diet promote increased insulin sensitivity. Insulin and insulin-like growth factor 1 (IGF-I) act as promoters of most normal and pre-neoplastic tissues. Conclusion: A plant-based diet high in fiber prevents disease by creating metabolites in the gut that reduce oxidative stress.

Caesarean section and risk of infection in offspring: systematic review and meta-analysis of observational studies

Objective

To compare the risk of hospital admissions with infections and infections not in hospital in children born by caesarean section with children born by vaginal birth.

Data sources

Medline, Embase, and PubMed were searched with no restriction on start date up to 12 February 2024.

Study selection

Observational studies were included that reported the association between caesarean section and vaginal birth in relation to the risk of infections (both those that lead to hospital admission and those that do not) up to 18 years of age. Studies were excluded if they were not representative of a general population or if they focused on congenital, neonatal, or vertically acquired infections. No restrictions were made for language, publication date, or setting.

Review methods

Findings for hospital admissions with infection were synthesised by meta-analyses of specific infection outcomes and type of caesarean birth (emergency v elective) and findings for other infections (ie, infection episodes reported by parents and primary care visits) by direction of effect. Risk of bias was assessed using the ROBINS-E tool and the overall certainty of evidence through the GRADE framework.

Results

31 eligible studies of over 10 million children were included. Findings were from population-based birth cohorts and registry data linkage studies in high income countries. Cohort sizes ranged from 288 to 7.2 million and follow up age was from one to 18 years. Outcomes included overall and specific clinical categories of infection. From studies of overall admission to hospital with infection, the proportion of children admitted ranged between 9-29% across exposure groups. In random-effects meta-analyses combining hazard ratios, children delivered by caesarean section had an increased rate of hospital admission with infections overall and in three common clinical infection categories: (1) overall admissions to hospital with infection (emergency caesarean section: n=6 study populations, hazard ratio 1.10 (95% confidence interval 1.06 to 1.14), τ 2=0.0009, I2=96%; elective caesarean section: n=7, 1.12 (1.09 to 1.15), τ 2=0.0006, I2=88%); (2) admission to hospital for upper respiratory infections (emergency caesarean section: n=7, 1.11 (1.09 to 1.13), τ 2=0.0003, I2=73%; elective caesarean section: n=7, 1.16 (1.12 to 1.20), τ 2=0.0012, I2=89%); (3) admission to hospital for lower respiratory infections (emergency caesarean section: n=8, 1.09 (1.06 to 1.12), τ 2=0.0010, I2=88%; elective caesarean section: n=8, 1.13 (1.10 to 1.16), τ 2=0.0009, I2=84%); (4) admission to hospital for gastrointestinal infections (emergency caesarean section: n=7, 1.19 (1.13 to 1.26), τ 2=0.0025, I2=86%; elective caesarean section: n=7, 1.20 (1.15 to 1.25), τ 2=0.0009, I2=67%). Eight of 11 studies of other infections suggested an increased risk of their primary infection outcome in those born by caesarean section. Risk of bias concerns primarily related to confounding.

Conclusions

Findings from high income countries showed a consistent association between caesarean section birth and greater risk of infections in children across various settings. Limitations of existing studies include the potential for unmeasured confounding, specifically confounding by indication, and a scarcity of studies from low and middle income countries.

Review registration

PROSPERO (CRD42022369252).

Mode of delivery and behavioral and neuropsychological outcomes in children at 10 years of age

OBJECTIVES

Previous studies have reported that mode of delivery, particularly cesarean delivery (CD), is associated with neurodevelopmental outcomes in children. This study evaluates behavioral and neuropsychological test scores in children based on mode of delivery.

METHODS

Children enrolled in the Raine Study from Western Australia, born between 1989 and 1992 by instrumental vaginal delivery (IVD), elective CD, and non-elective CD, were compared to those with spontaneous vaginal delivery (SVD). The primary outcome was the Child Behavior Checklist (CBCL) administered at age 10. Secondary outcomes included evaluations of language, motor function, cognition, and autistic traits. Multivariable linear regression was used to evaluate score differences by mode of delivery adjusted for sociodemographic and clinical characteristics, and Poisson regression was used to evaluate for increased risk of clinical deficit.

RESULTS

Of 2,855 children, 1770 (62.0 %) were delivered via SVD, 480 (16.8 %) via IVD, 346 (12.1 %) via elective CD, and 259 (9.1 %) via non-elective CD. Non-elective CD was associated with higher (worse) CBCL Internalizing (+2.09; 95 % CI 0.49, 3.96; p=0.01) scores, and elective CD was associated with lower (worse) McCarron Assessment of Neuromuscular Development (MAND) (-3.48; 95 % CI -5.61, -1.35; p=0.001) scores. Differences were not seen in other outcomes, and increased risk of clinical deficit was not observed with either the CBCL Internalizing or MAND scores.

CONCLUSIONS

Differences in behavior and motor function were observed in children delivered by CD, but given that score differences were not associated with increased incidence of clinical deficit, clinical significance may be limited.

Early life events may be the first steps on the multistep path to amyotrophic lateral sclerosis

A combination of multiple genetic and environmental factors appear to be required to trigger the onset of amyotrophic lateral sclerosis (ALS). Early life environmental exposures have been reported to be risk factors for a variety of adult-onset diseases, so we used data from an online international ALS case-control questionnaire to estimate whether any of these could be risk factors for the clinical onset of ALS. Responses were obtained from 1,049 people aged 40 years or more, 568 with ALS and 481 controls. People with ALS were more likely to have been born and lived longer in a country area than in a city area, to have younger parents, and to have lower educational attainment and fewer years of education. No ALS-control differences were found in sibling numbers, birth order, adult height, birth weight, parent smoking, Cesarean delivery, or age of starting smoking. In conclusion, early life events and conditions may be part of a group of polyenvironmental risk factors that act together with polygenetic variants to trigger the onset of ALS. Reducing exposure to adverse environmental factors in early life could help to lower the risk of later developing ALS.

Is There an Association Between Cesarean Section Delivery with Specific Learning Disabilities (SLD) or/and Attention-Deficit/Hyperactivity Disorder (ADHD)? A Cross-Sectional Study in Greek Population

BACKGROUND/OBJECTIVE

Learning difficulties (LDs) are lifelong neurodevelopmental disorders with multifactorial causes, including perinatal factors like mode of delivery. This study aims to explore whether cesarean section (CS) delivery is linked to the occurrence of specific learning disabilities (SLDs), attention-deficit/hyperactivity disorder (ADHD), or their comorbidity.

METHODS

An online questionnaire was distributed via Google Forms to Greek mothers and parents of children with and without diagnoses, shared through school-related groups and various Greek pages focused on child development, special education, and learning difficulties. Conducted over eight months (October 2023-May 2024), this cross-sectional study involved 256 children, 137 with LDs diagnoses, and 119 controls.

RESULTS

In total, 59.9% of CS-born children had a diagnosis, compared to 40.1% of those born vaginally (X²(1) = 4.19, p = 0.045). CS delivery was associated with a 68% increased likelihood of LDs (OR = 1.68, 95% CI [1.02, 2.76]), with higher risks for ADHD (OR = 2.25, 95% CI [1.06, 4.79]) and comorbid SLD/ADHD diagnoses (OR = 2.75, 95% CI [1.17, 6.46]). Stratified analyses showed birthweight and gestational age as effect modifiers rather than confounders. Key postnatal risk factors identified were family history (OR = 4.65, 95% CI [2.41, 8.94]) and language acquisition difficulties (OR = 5.28, 95% CI [1.36, 20.47]).

CONCLUSIONS

The findings suggest a possible association between CS and LDs, along with a novel link between CS and increased comorbidities. These results underscore the need for further research and provide valuable insights into how CS delivery may influence the risk of LDs, depending on the type of diagnosis.

Long-term exposure to ozone and sleep disorders in children: A multicity study in China

Evidence regarding the link between long-term ambient ozone (O3) exposure and childhood sleep disorders is little. This study aims to examine the associations between long-term exposure to O3 and sleep disorders in children. We conducted a population-based cross-sectional survey, including 185,428 children aged 6-18 years in 173 schools across 14 Chinese cities during 2012 and 2018. Parents or guardians completed a checklist using Sleep Disturbance Scale for Children, and O3 exposure at residential and school addresses was estimated using a satellite-based spatiotemporal model. We used generalized linear mixed models to test the associations with adjustment for factors including socio-demographic variables, lifestyle, meteorology and multiple pollutants. Mean concentrations of O3, particulate matter with diameters ≤2.5 mm (PM2.5) and nitrogen dioxide (NO2) were 89.0 μg/m3, 42.5 μg/m3 and 34.4 μg/m3, respectively. O3 and NO2 concentrations were similar among provinces, while PM2.5 concentration varied significantly among provinces. Overall, 19.4% of children had at least one sleep disorder. Long-term exposure to O3 was positively associated with odds of sleep disorders for all subtypes. For example, each interquartile increment in home-school O3 concentrations was associated with a higher odds ratio for global sleep disorder, at 1.22 (95% confidence interval: 1.18, 1.26). Similar associations were observed for sleep disorder subtypes. The associations remained similar after adjustment for PM2.5 and NO2. Moreover, these associations were heterogeneous regionally, with more prominent associations among children residing in southeast region than in northeast and northwest regions in China. We concluded that long-term exposure to O3 is positively associated with risks of childhood sleep disorders. These associations varied by geographical region of China.

Regional differences in autism and intellectual disability risk associated with cesarean section delivery

Prior epidemiological studies investigating the association between delivery mode (i.e., vaginal birth and cesarean section [C-section]) and autism spectrum disorder (ASD) and intellectual disability (ID) risk have reported mixed findings. This study examined ASD and ID risks associated with primary and repeat C-section within diverse US regions. During even years 2000-2016, 8-years-olds were identified with ASD and/or ID and matched to birth records [ASD only (N = 8566, 83.6% male), ASD + ID (N = 3445, 79.5% male), ID only (N = 6158, 60.8% male)] using the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring Network methodology. The comparison birth cohort (N = 1,456,914, 51.1% male) comprised all births recorded in the National Center for Health Statistics corresponding to birth years and counties in which surveillance occurred. C-section rates in the birth cohort demonstrated significant regional variation with lowest rates in the West. Overall models demonstrate increased odds of disability associated with primary and repeat C-section. Adjusted models, stratified by region, identified significant variability in disability likelihood associated with repeat C-section: increased odds occurred for all case groups in the Southeast, for ASD only and ID only in the Mid-Atlantic, and no case groups in the West. Regional variability in disability risk associated with repeat C-section coincides with differences in birth cohorts' C-section rates. This suggests increased likelihood of disability is not incurred by the procedure itself, but rather C-section serves as a proxy for exposures with regional variability that influence fetal development and C-section rates.

Association between mode of delivery and early neurodevelopment: A prospective birth cohort study

Previous research has assessed the effects of caesarean delivery (CD) on child neurodevelopment; however, whether the effects stem from the surgical procedure itself or its related medical conditions has not been conclusively determined. This study aimed to evaluate the associations among delivery mode, CD-related medical conditions and early childhood neurodevelopment. A total of 3829 maternal-infant pairs from a longitudinal birth cohort in Wuhan City, China, were included in the primary analysis. The neurodevelopment of the children was assessed by the Bayley Scales of Infant Development (BSID), the Conners Comprehensive Behaviour Rating Scale and the Chinese version of the Autism Behavior Checklist. Data on delivery mode and medical conditions were collected via medical records from the study hospital. Among the 3829 children for whom the BSID test was completed at two years of age, 50%, 27%, and 23% were delivered vaginally, by necessary CD, and by elective CD, respectively. Compared with vaginally delivered children, Necessary CD was associated with a 16.67% decrease in Mental Development Index (MDI) scores and a 13.37% decrease in Psychomotor Development Index (PDI) scores, while elective CD showed a 20.63% and 20.99% decrease after FDR correction, respectively. Similarly, among the 2448 children for whom the CBRS was completed, necessary CD was found to be associated with conduct disorders (adjusted β: 0.06; 95% CI: 0.02, 0.09), hyperactivity (adjusted β: 0.06; 95% CI: 0.02, 0.11), and hyperactivity index (adjusted β: 0.07; 95% CI: 0.03, 0.11), while elective CD was significantly associated with hyperactivity problem scores (adjusted β: 0.08, 95% CI: 0.03, 0.13). However, no significant association was found between CD and symptoms of autism in children, as assessed by the Autism Behavior Checklist (ABC).

CONCLUSION

This study suggested that the adverse impact of CD on child neurodevelopment stems from the procedure itself rather than CD-related medical conditions. It is important to minimize the use of CD when there is no medical necessity.

WHAT IS KNOWN

• Caesarean delivery (CD) may influence child neurodevelopment and other long-term outcomes. • In China, approximately one-quarter of CD are performed due to maternal request without medical indications.

WHAT IS NEW

• The negative impact of CD on the neurodevelopmental outcomes of children may be primarily attributed to the procedure itself, as opposed to related medical conditions. • In the absence of medical indications, unnecessary CD may have adverse impacts on children's neurodevelopment.

Maternal Eating Disorders, Body Mass Index, and Offspring Psychiatric Diagnoses

Importance

Maternal nutrition is essential in fetal development; thus, disordered eating may influence this process and contribute to the development of offspring psychiatric disorders.

Objective

To investigate the association of maternal eating disorders and prepregnancy body mass index (BMI) with offspring psychiatric diagnoses.

Design, Setting, and Participants

This population-based cohort study used Finnish national registers to assess all live births from January 1, 2004, through December 31, 2014, with follow-up until December 31, 2021. The data analyses were conducted from September 1, 2023, to September 30, 2024.

Exposures

Maternal eating disorder and prepregnancy BMI.

Main Outcomes and Measures

Primary outcomes were 9 neurodevelopmental and psychiatric offspring diagnoses. Cox proportional hazards modeling adjusted for potential risk factors in the development of the outcome disorders was applied in 2 models. Secondary analyses were stratified for adverse birth outcomes (prematurity, small size for gestational age, and low Apgar score) or comorbid offspring eating disorders. Categories of BMI (calculated as weight in kilograms divided by height in meters squared) included underweight (BMI <18.5), normal weight (18.5-24.9), overweight (25.0-29.9), obesity (30.0-34.9), and severe obesity (≥35.0).

Results

The mean (SD) age of 392 098 included mothers was 30.15 (5.38) years, 42 590 mothers (10.86%) were born outside of Finland, 6273 mothers (1.60%) had a history of an eating disorder, 23 114 mothers (5.89%) had prepregnancy underweight, and 208 335 (53.13%) mothers had overweight or obesity. Among 649 956 included offspring, 332 359 (51.14%) were male, and 106 777 (16.43%) had received a neurodevelopmental or psychiatric diagnosis. Maternal eating disorders, prepregnancy underweight, and overweight or obesity were associated with most of the studied mental diagnoses in offspring, even after adjusting for potential covariates. The largest effect sizes were observed for maternal eating disorders not otherwise specified in association with offspring sleep disorders (hazard ratio [HR], 3.34 [95% CI, 2.39-4.67]) and social functioning and tic disorders (HR, 2.79 [95% CI, 2.21-3.52]), while for maternal severe prepregnancy obesity, offspring intellectual disabilities (HR, 2.04 [95% CI, 1.83-2.28]) had the largest effect size. Adverse birth outcomes further increased the risk of offspring having other feeding disturbances of childhood and infancy (eg, HR, 4.53 [95% CI, 2.97-6.89] for maternal eating disorders) and attention-deficit/hyperactivity disorder and conduct disorder (eg, HR, 2.27 [95% CI, 1.74-2.96] for maternal anorexia nervosa).

Conclusions and Relevance

In this population-based cohort study including 392 098 mothers and 649 956 offspring, offspring from mothers with an eating disorder history or prepregnancy BMI outside normal weight were at higher risk of psychiatric disorders. The results differed somewhat between the 2 exposures with regard to which offspring diagnoses had associations, and effect sizes were typically larger for maternal eating disorders vs BMI. These findings suggest a need to consider these 2 exposures clinically to help prevent offspring mental illness.

The Microbiota-Gut-Brain Axis and Neurological Disorders: A Comprehensive Review

Microbes have inhabited the earth for hundreds of millions of years longer than humans. The microbiota-gut-brain axis (MGBA) represents a bidirectional communication pathway. These communications occur between the central nervous system (CNS), the enteric nervous system (ENS), and the emotional and cognitive centres of the brain. The field of research on the gut-brain axis has grown significantly during the past two decades. Signalling occurs between the gut microbiota and the brain through the neural, endocrine, immune, and humoral pathways. A substantial body of evidence indicates that the MGBA plays a pivotal role in various neurological diseases. These include Alzheimer's disease (AD), autism spectrum disorder (ASD), Rett syndrome, attention deficit hyperactivity disorder (ADHD), non-Alzheimer's neurodegeneration and dementias, fronto-temporal lobe dementia (FTLD), Wilson-Konovalov disease (WD), multisystem atrophy (MSA), Huntington's chorea (HC), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), temporal lobe epilepsy (TLE), depression, and schizophrenia (SCZ). Furthermore, the bidirectional correlation between therapeutics and the gut-brain axis will be discussed. Conversely, the mood of delivery, exercise, psychotropic agents, stress, and neurologic drugs can influence the MGBA. By understanding the MGBA, it may be possible to facilitate research into microbial-based interventions and therapeutic strategies for neurological diseases.

Female Infertility and Neurodevelopmental Disorders in Children: associations and evidence for familial confounding in Denmark

IMPORTANCE

Existing research suggests the impact of infertility on the risk of neurodevelopmental disorders in children, however, studies to date have failed to separate the impact of male and female infertility, often blurring the lines with proxies that encompass all forms of infertility. Moreover, while both health conditions co-occurring with infertility and genetic factors operating upstream have been suggested to influence the association between infertility and child outcomes, their roles and potential impact on observed associations remain unclear.

OBJECTIVE

The objectives of this study are to investigate the relationship between female infertility and autism in the child, differentiating it from the effects of male and the couple infertility; consider the role of various maternal and birth factors in the association; and examine the effects of shared familial confounders on the association.

DESIGN SETTING AND PARTICIPANTS

Danish population-based cohort study, including all singleton live births in Denmark 1998-2015, their parents and parents' siblings. The cohort was followed up until December 31, 2016.

EXPOSURES

The exposure was a history of female infertility in the mother and the mother's sister. We examined four definitions of female infertility based on the ICD-10 codes derived from the Danish National Patient Register - any female infertility; specified female infertility; female exclusive infertility; and female or male infertility.

MAIN OUTCOME AND MEASURES

The outcome was diagnosis of autism spectrum disorder (ASD) in the Danish Psychiatric Central Research Register or the national patient register. A multivariable Cox regression model was used to estimate the associations between female infertility and autism, accounting for child's sex, year of birth, maternal age, education level, chronic comorbidities, and pregnancy and birth complications. The effects of shared familial factors on the association were analyzed using exposure information from the child's maternal aunt.

RESULTS

The cohort included 1,131,899 mother-child pairs, among which 18,374 children with ASD diagnosis. History of female infertility in the mother (all definitions) was significantly associated with autism in the child, with the association remaining robust after adjustment for covariates (HRadj=1.14 (95% CI, 1.03-1.26) for specified infertility). The diagnosis of infertility in a child's maternal aunt was also significantly linked to the child's autism risk, even after adjustment for maternal infertility (HRadj=1.10 (95% CI, 1.00-1.20).

CONCLUSIONS AND RELEVANCE

in This population-based birth cohort study, we found a slightly higher risk of autism in children born to mothers with a history of infertility, with the association remaining consistent across various definitions of female infertility and robust to adjustments for demographic, child, and maternal factors. The study suggests for the first time that shared familial factors, possibly both genetic and non-genetic, could be influencing both female infertility and the risk of autism in children, indicating a need for further investigation into these familial effects.

Exploring Cesarean Section Delivery Patterns in South India: A Bayesian Multilevel and Geospatial analysis of Population-Based Cross-Sectional Data

BACKGROUND

This paper focuses on the period from 2019 to 2021 and investigates the factors associated with the high prevalence of C-section deliveries in South India. We also examine the nuanced patterns, socio-demographic associations, and spatial dynamics underlying C-section choices in this region. A cross-sectional study was conducted using large nationally representative survey data.

METHODS

National Family Health Survey data (NFHS) from 2019 to 2021 have been used for the analysis. Bayesian Multilevel and Geospatial Analysis have been used as statistical methods.

RESULTS

Our analysis reveals significant regional disparities in C-section utilization, indicating potential gaps in healthcare access and socio-economic influences. Maternal age at childbirth, educational attainment, healthcare facility type size of child at birth and ever pregnancy termination are identified as key determinants of method of C-section decisions. Wealth index and urban residence also play pivotal roles, reflecting financial considerations and access to healthcare resources. Bayesian multilevel analysis highlights the need for tailored interventions that consider individual household, primary sampling unit (PSU) and district-level factors. Additionally, spatial analysis identifies regions with varying C-section rates, allowing policymakers to develop targeted strategies to optimize maternal and neonatal health outcomes and address healthcare disparities. Spatial autocorrelation and hotspot analysis further elucidate localized influences and clustering patterns.

CONCLUSION

In conclusion, this research underscores the complexity of C-section choices and calls for evidence-based policies and interventions that promote equitable access to quality maternal care in South India. Stakeholders must recognize the multifaceted nature of healthcare decisions and work collaboratively to ensure more balanced and effective healthcare practices in the region.

Exposures to particulate matters and childhood sleep disorders-A large study in three provinces in China

OBJECTIVES

Evidence on the link between long-term ambient particulate matter (PM) exposures and childhood sleep disorders were scarce. We examined the associations between long-term exposures to PM2.5 and PM1 (PM with an aerodynamic equivalent diameter <2.5 μm and <1 μm, respectively) with sleep disorders in children.

METHODS

We performed a population-based cross-sectional survey in 177,263 children aged 6 to 18 years in 14 Chinese cities during 2012-2018. A satellite-based spatiotemporal model was employed to estimate four-year annual average PM2.5 and PM1 exposures at residential and school addresses. Parents or guardians completed a checklist using the Sleep Disturbance Scale for Children. We estimated the associations using generalized linear mixed models with adjustment for characteristics of children, parents, and indoor environments.

RESULTS

Long-term PM2.5 and PM1 exposures were positively associated with odds of sleep disorders for almost all domains. For example, increments in PM2.5 and PM1 per 10 μg/m3 were associated with odds ratios of global sleep disorder of 1.24 (95 % confidence interval [CI]: 1.14, 1.35) and 1.31 (95 %CI: 1.18, 1.46), respectively. Similar results were observed for subtypes of sleep disorder. These associations were heterogeneous regionally, with stronger associations among children residing in southeast region than in northeast and northwest regions. Moreover, larger estimates of PM1 were found than that of PM2.5 in southeast region.

CONCLUSION

Long-term PM2.5 and PM1 exposures are independently associated with higher risks of childhood sleep disorders, and these associations vary by geographical region.

Cord serum cytokines at birth and children's trajectories of mood dysregulation symptoms from 3 to 8 years: The EDEN birth cohort

There is growing evidence that in utero imbalance immune activity plays a role in the development of neurodevelopmental and psychiatric disorders in children. Mood dysregulation (MD) is a debilitating transnosographic syndrome whose underlying pathophysiological mechanisms could be revealed by studying its biomarkers using the Research Domain Criteria (RDoC) model. Our aim was to study the association between the network of cord serum cytokines, and mood dysregulation trajectories in offsprings between 3 and 8 years of age. We used the data of a study nested in the French birth cohort EDEN that took place from 2003 to 2014 and followed mother-child dyads from the second trimester of pregnancy until the children were 8 years of age. The 2002 mother-child dyads were recruited from the general population through their pregnancy follow-up in two French university hospitals. 871 of them were included in the nested cohort and cord serum cytokine levels were measured at birth. Children's mood dysregulation symptoms were assessed with the Strengths and Difficulties Questionnaire Dysregulation Profile at the ages 3, 5 and 8 years in order to model their mood dysregulation trajectories. Out of the 871 participating dyads, 53% of the children were male. 2.1% of the children presented a high mood dysregulation trajectory whereas the others were considered as physiological variations. We found a significant negative association between TNF-α cord serum levels and a high mood dysregulation trajectory when considering confounding factors such as maternal depression during pregnancy (adjusted Odds Ratio (aOR) = 0.35, 95% Confidence Interval (CI) [0.18-0.67]). Immune imbalance at birth could play a role in the onset of mood dysregulation symptoms. Our findings throw new light on putative immune mechanisms implicated in the development of mood dysregulation and should lead to future animal and epidemiological studies.

Food, nutrition, and autism: from soil to fork

Food and nutrition-related factors have the potential to impact development of autism spectrum disorder (ASD) and quality of life for people with ASD, but gaps in evidence exist. On 10 November 2022, Tufts University's Friedman School of Nutrition Science and Policy and Food and Nutrition Innovation Institute hosted a 1-d meeting to explore the evidence and evidence gaps regarding the relationships of food and nutrition with ASD. This meeting report summarizes the presentations and deliberations from the meeting. Topics addressed included prenatal and child dietary intake, the microbiome, obesity, food-related environmental exposures, mechanisms and biological processes linking these factors and ASD, food-related social factors, and data sources for future research. Presentations highlighted evidence for protective associations with prenatal folic acid supplementation and ASD development, increases in risk of ASD with maternal gestational obesity, and the potential for exposure to environmental contaminants in foods and food packaging to influence ASD development. The importance of the maternal and child microbiome in ASD development or ASD-related behaviors in the child was reviewed, as was the role of discrimination in leading to disparities in environmental exposures and psychosocial factors that may influence ASD. The role of child diet and high prevalence of food selectivity in children with ASD and its association with adverse outcomes were also discussed. Priority evidence gaps identified by participants include further clarifying ASD development, including biomarkers and key mechanisms; interactions among psychosocial, social, and biological determinants; interventions addressing diet, supplementation, and the microbiome to prevent and improve quality of life for people with ASD; and mechanisms of action of diet-related factors associated with ASD. Participants developed research proposals to address the priority evidence gaps. The workshop findings serve as a foundation for future prioritization of scientific research to address evidence gaps related to food, nutrition, and ASD.

Early environmental predictors for attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and their co-occurrence: The prospective ABIS-Study

ADHD and ASD are highly heritable and show a high co-occurrence and persistence into adulthood. This study aimed to identify pre and perinatal risk factors, and early psychosocial exposures related to later diagnosis of ADHD, ASD, and their co-occurrence. 16,365 children born 1997-1999 and their families, involved in the prospective population-based ABIS study (All Babies in Southeast Sweden), were included in this sub-study. Pre and perinatal factors and early environmental psychosocial exposures were collected from parental-questionnaires at birth and 1-year follow-up. Diagnoses from birth up to 23 years of age were obtained from the Swedish National Diagnosis Register in 2020. The cumulative incidence of ADHD, ASD, and their co-occurrence in the ABIS-cohort Study were 4.6%, 1.7%, and 1.1%, respectively. Being male was associated with an increased risk for ADHD, ASD, and their co-occurrence (aOR 1.30, 1.56, and 1.91, respectively), while higher household income reduced it (aOR 0.82, 0.73, and 0.64). Serious life events during pregnancy (aOR 1.40) and maternal smoking (aOR 1.51) increased the risk of ADHD, while older maternal age (aOR 0.96), higher parental education (aOR 0.72 maternal and aOR 0.74 paternal) and longer exclusive breastfeeding (aOR 0.72) reduced it. Non-Swedish paternal nationality (aOR 0.40) and higher maternal education (aOR 0.74) were associated with a lower risk of ASD, while a family history of autoimmune diseases increased the risk of the co-occurrence of both disorders (aOR 1.62). Obtained results suggest that the etiology of ADHD, ASD, and their co-occurrence is independently associated with environmental psychosocial predictors. The co-occurrence seems to overlap the etiology of ADHD, in which psychosocial determinants have a larger role, however, it is also independently influenced by a family history of autoimmune diseases.

Exploration of Risk Factors for Language Regression According to Parent Reports in Turkish Children with Autism Spectrum Disorder

Background

Approximately 30% of autism spectrum disorder (ASD) cases exhibit developmental regression after a period of typical development, leading to what is known as regressive autism. Our understanding of the factors underlying regression, including precise mechanisms, clinical features, and risk factors, remains limited. This study aims to compare children with ASD with language regression (ASD-LR) to those without developmental regression (ASD-NR) in terms of clinical and demographic characteristics and to identify potential predictors.

Methods

In this cross-sectional retrospective study, children aged 2-6 diagnosed with ASD-LR were matched for age and gender with children diagnosed with ASD-NR between January 2023 and January 2024. The groups were compared in terms of demographic and clinical characteristics.

Results

The mean age of the ASD-LR group (n = 32) was 52.16 ± 14.56 months, and the ASD-NR group (n = 50) had a mean age of 48.76 ± 13.41 months. Univariate analyses revealed no significant differences in autism severity between groups in clinician (P = .367) and parent evaluations (P = .541). However, in the ASD-LR group, a significant relationship was found between regression, a history of febrile seizures (P = .012), a father's psychiatric background (P = .002), and a family history of psychiatric disorders (P < .001). Family history of psychiatric disorders (OR 7.54, 95% CI 1.10-51.64, P = .040) and cesarean delivery (odds ratio 3.90, 95% CI 1.05-14.47, P = .042) were identified as independent predictors of language regression.

Conclusion

The results indicate that regression may be associated with both genetic and environmental factors, including a family history of psychiatric disorders, cesarean delivery, and febrile seizure. Future research should focus on explaining these factors and identifying potential preventive measures.

Likelihood of primary cesarean section following induction of labor in singleton cephalic pregnancies at term, compared with expectant management: An Australian population-based, historical cohort study

INTRODUCTION

There has been increased use of both induction of labor (IOL) and cesarean section for women with term pregnancies in many high-income countries, and a trend toward birth at earlier gestational ages. Existing evidence regarding the association between IOL and cesarean section for term pregnancies is mixed and conflicting, and little evidence is available on the differential effect at each week of gestation, stratified by parity.

MATERIAL AND METHODS

To explore the association between IOL and primary cesarean section for singleton cephalic pregnancies at term, compared with two definitions of expectant management (first: at or beyond the week of gestation at birth following IOL; and secondary: only beyond the week of gestation at birth following IOL), we performed analyses of population-based historical cohort data on women who gave birth in one Australian state (Queensland), between July 1, 2012 and June 30, 2018. Women who gave birth before 37+0 or after 41+6 weeks of gestation, had stillbirths, no-labor, multiple births (twins or triplets), non-cephalic presentation at birth, a previous cesarean section, or missing data on included variables were excluded. Four sub-datasets were created for each week at birth (37-40). Unadjusted relative risk, adjusted relative risk using modified Poisson regression, and their 95% confidence intervals were calculated in each sub-dataset. Analyses were stratified by parity (nulliparas vs. parous women with a previous vaginal birth). Sensitivity analyses were conducted by limiting to women with low-risk pregnancies.

RESULTS

A total of 239 094 women were included in the analysis, 36.7% of whom gave birth following IOL. The likelihood of primary cesarean section following IOL in a Queensland population-based cohort was significantly higher at 38 and 39 weeks, compared with expectant management up to 41+6 weeks, for both nulliparas and paras with singleton cephalic pregnancies, regardless of risk status of pregnancy and definition of expectant management. No significant difference was found for nulliparas at 37 and 40 weeks; and for paras at 40 weeks.

CONCLUSIONS

Future studies are suggested to investigate further the association between IOL and other maternal and neonatal outcomes at each week of gestation in different maternal populations, before making any recommendation.

Prenatal opioid exposure and subsequent risk of neuropsychiatric disorders in children: nationwide birth cohort study in South Korea

OBJECTIVE

To investigate the potential association between prenatal opioid exposure and the risk of neuropsychiatric disorders in children.

DESIGN

Nationwide birth cohort study.

SETTING

From 1 January 2009 to 31 December 2020, birth cohort data of pregnant women in South Korea linked to their liveborn infants from the National Health Insurance Service of South Korea were collected.

PARTICIPANTS

All 3 251 594 infants (paired mothers, n=2 369 322; age 32.1 years (standard deviation 4.2)) in South Korea from the start of 2010 to the end of 2017, with follow-up from the date of birth until the date of death or 31 December 2020, were included.

MAIN OUTCOME MEASURES

Diagnosis of neuropsychiatric disorders in liveborn infants with mental and behaviour disorders (International Classification of Diseases 10th edition codes F00-99). Follow-up continued until the first diagnosis of neuropsychiatric disorder, 31 December 2020 (end of the study period), or the date of death, whichever occurred first. Eight cohorts were created: three cohorts (full unmatched, propensity score matched, and child screening cohorts) were formed, all of which were paired with sibling comparison cohorts, in addition to two more propensity score groups. Multiple subgroup analyses were performed.

RESULTS

Of the 3 128 571 infants included (from 2 299 664 mothers), we identified 2 912 559 (51.3% male, 48.7% female) infants with no prenatal opioid exposure and 216 012 (51.2% male, 48.8% female) infants with prenatal opioid exposure. The risk of neuropsychiatric disorders in the child with prenatal opioid exposure was 1.07 (95% confidence interval 1.05 to 1.10) for fully adjusted hazard ratio in the matched cohort, but no significant association was noted in the sibling comparison cohort (hazard ratio 1.00 (0.93 to 1.07)). Prenatal opioid exposure during the first trimester (1.11 (1.07 to 1.15)), higher opioid doses (1.15 (1.09 to 1.21)), and long term opioid use of 60 days or more (1.95 (1.24 to 3.06)) were associated with an increased risk of neuropsychiatric disorders in the child. Prenatal opioid exposure modestly increased the risk of severe neuropsychiatric disorders (1.30 (1.15 to 1.46)), mood disorders, attention deficit hyperactivity disorder, and intellectual disability in the child.

CONCLUSIONS

Opioid use during pregnancy was not associated with a substantial increase in the risk of neuropsychiatric disorders in the offspring. A slightly increased risk of neuropsychiatric disorders was observed, but this should not be considered clinically meaningful given the observational nature of the study, and limited to high opioid dose, more than one opioid used, longer duration of exposure, opioid exposure during early pregnancy, and only to some neuropsychiatric disorders.

Delivery by cesarean section leads to heavier adult bodyweight in prairie voles (Microtus ochrogaster)

Delivery by cesarean section now makes up 32.1 % of all births in the United States. Meta-analyses have estimated that delivery by cesarean section is associated with a > 50 % increased risk for childhood obesity by 5 years of age. While this association is independent of maternal obesity, breastfeeding, and heritable factors, studies in humans have been unable to test for a causal role of cesarean delivery in this regard. Here, we set out to use an animal model to experimentally test whether delivery by cesarean section would increase offspring weight in adulthood. Delivery by cesarean section may exert neurodevelopmental consequences by impacting hormones that are important at birth as well as during metabolic regulation in later life, such as oxytocin and vasopressin. The prairie vole (Microtus ochrogaster) has long been studied to investigate the roles of oxytocin and vasopressin in brain development and social behavior. Here, we establish that prairie voles tolerate a range of ambient temperatures, including conventional 22° housing, which makes them translationally appropriate for studies of diet-induced obesity. We also studied vole offspring for their growth, sucrose preference, home cage locomotor activity, and food consumption after birth by either cesarean section or vaginal delivery. At sacrifice, we collected measures of weight, length, and adipose tissue to analyze body composition in adulthood. Voles delivered by cesarean section had consistently greater bodyweights than those born vaginally, despite having lower food consumption and greater locomotive activity. Cesarean-delivered animals were also longer, though this did not explain their greater body weights. While cesarean delivery had no effect on vasopressin, it resulted in less oxytocin immunoreactivity within the hypothalamus in adulthood. These results support the case that cesarean section delivery plays a causal role in increasing offspring body weight, potentially by affecting the oxytocin system.

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.

Rett syndrome in Ireland: a demographic study

BACKGROUND

Rett syndrome (RTT) is a rare neurodevelopmental condition associated with mutations in the gene coding for the methyl-CpG-binding protein 2 (MECP2). It is primarily observed in girls and affects individuals globally. The understanding of the neurobiology of RTT and patient management has been improved by studies that describe the demographic and clinical presentation of individuals with RTT. However, in Ireland, there is a scarcity of data regarding individuals with RTT, which impedes the ability to fully characterize the Irish RTT population. Together with the Rett Syndrome Association of Ireland (RSAI), we prepared a questionnaire to determine the characteristics of RTT individuals in Ireland. Twenty-five families have participated in the study to date, providing information about demographics, genetics, familial history, clinical features, and regression.

RESULTS

The results show that Irish individuals with RTT have comparable presentation with respect to individuals in other countries; however, they had a better response to anti-epileptic drugs, and fewer skeletal deformities were reported. Nonetheless, seizures, involuntary movements and regression were more frequently observed in Irish individuals. One of the main findings of this study is the limited genetic information available to individuals to support the clinical diagnosis of RTT.

CONCLUSIONS

Despite the limited sample size, this study is the first to characterize the RTT population in Ireland and highlights the importance of having a swift access to genetic testing to sharpen the characterization of the phenotype and increase the visibility of Irish individuals in the international RTT community.

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.

Risk factors and clinical profile of autism spectrum disorder in southern Brazil

In Brazil, as in other countries, it is expected a significant variation of epidemiological and clinical characteristics among individuals with autism spectrum disorder (ASD). This study was performed to explore maternal risk factors and clinical characteristics of children with ASD in a population located in southern Brazil. Data were collected from medical records and analyzed to explore biomarkers associated with ASD. Out of 321 children with ASD, 86.5% were males with a male-to-female ratio of 5.7:1, 50.7% were mild/moderate while 49.3% presented severe ASD. Between the risk factors investigated, gestational infection was significantly associated with severe ASD patients. There was also an association between epilepsy and severe autism. Several gastrointestinal (GI) symptoms were significantly associated with severe ASD. Obesity, followed by lower levels of cholesterol, were also significant factors associated with an ASD diagnosis when compared to age-matched controls. Finally, severe ASD was associated with significantly higher serum serotonin levels when compared to age-matched controls and mild/moderate ASD cases. Our findings demonstrate that our population shares many features associated with ASD around the world, such as GI symptoms, epilepsy, and high serotonin levels. It is worth highlighting the low cholesterol levels associated with obesity as an unusual feature that deserves more attention.

Effects of SARS-CoV-2 gestational exposure and risk factors on neurodevelopment until 12 months: A prospective cohort study in Brazil

BACKGROUND

The effects of SARS-CoV-2 gestational exposure on child development remain inconclusive.

AIMS

To analyze the effects of SARS-CoV-2 gestational exposure on neurodevelopment until 12 months.

STUDY DESIGN

Prospective cohort study conducted in five municipalities in Southeast Brazil from August 2021 to September 2022.

SUBJECTS

Infants were recruited from a serological survey performed during neonatal screening and followed up to 12 months old. We included 224 infants exposed to SARS-CoV-2 during pregnancy and 225 non-exposed, according to the serology results of the newborn as well as their mothers and the maternal antenatal RT-PCR results.

OUTCOME MEASURES

Developmental assessments were performed at 6 and 12 months using the Survey of Wellbeing of Young Children-Brazilian Version (SWYC-BR). Children with suspected developmental delay (SDD) at 6 and 12 months were considered at high risk for developmental delay (HRDD). Additionally, risk factors associated with SDD were examined.

RESULTS

There were 111 children identified with SDD and 52 with HRDD. SARS-CoV-2 gestational exposure was not associated with SDD. Exposure in the first gestational trimester increased SDD risk by 2.15 times compared to the third. Cesarean delivery predicted SDD (OR 1.56; 95%CI 1.01-2.42) and HRDD (OR 1.91; 95%CI 1.04-3.48). Additionally, suspected maternal depression predicted SDD (OR 1.76; 95%CI 1.01-3.10).

CONCLUSION

SARS-CoV-2 gestational exposure did not increase the developmental delay risk. However, our findings suggest that the earlier the gestational exposure, the greater the developmental delay risk at 12 months. Cesarean delivery and suspected maternal depression increased the developmental delay risk, independent of virus exposure.

Microbiota transplantation in restoring cesarean-related infant dysbiosis: a new frontier

C-section is crucial in reducing maternal and neonatal mortality when medically indicated, but one of its side effects could be the disruption of vertical transmission of maternal-infant microbiota during delivery, potentially leading to gut dysbiosis and increased disease risks in C-section infants. To address such dysbiosis, it seems reasonable to supplement "what is missing" during C-section procedure. This idea has prompted several clinical trials, including proof-of-concept, investigating interventions like vaginal microbial seeding, oral administration of maternal vaginal microbes and even oral administration of maternal fecal materials. Hereby, we have summarized these trials to help understand the current state of these researches, highlighting the predominantly pilot nature of most of these studies and emphasizing the need for well-designed studies with larger sample to guide evidence-based medicine in the future.

More than just a number: the gut microbiota and brain function across the extremes of life

Understanding the interrelationship between the gut microbiota and host physiology, although still in its relative infancy, has taken important steps forward over the past decade. In the context of brain disorders including those characterized by neurodevelopmental and neurodegenerative changes there have been important advances. However, initially research involved correlational analyses, had limited translational scope, and lacked functional assessments. Thus, largescale longitudinal clinical investigations that assess causation and underlying mechanisms via in depth analysis methods are needed. In neurodegeneration research, strong causal evidence now links the gut microbiome to Alzheimer's (AD), and Parkinson's Disease (PD), as supported by human-to-animal transplantation studies. Longitudinal interventions are being conducted in AD, PD, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis. Neurodevelopmental research has also seen a boon in microbiome-related clinical research including in autism, Attention-deficit/hyperactivity disorder, and schizophrenia, which is confirming prior animal model work regarding the key time-windows in the gut microbiome important for infant cognition. While recent research advances represent important progress, fundamental knowledge gaps and obstacles remain. Knowing how and why the gut microbiome changes at the extremes of life will develop our mechanistic understanding and help build the evidence base as we strive toward counteracting microbial missteps with precision therapeutic interventions.

A Higher Maternal Education Level Could Be a Critical Factor in the Exceeded Cesarean Section Delivery in Indonesia

Background

Cesarean section (CS) could be life-saving with medically indicated, but without it, both women and children could be at risk. The maximum rate for CS is 15%, but it tends to exceed globally.

Objective

We aimed to analyze the education level's role in the delivery of CS in Indonesia.

Methods

We used the 2017 Indonesia Demographic and Health Survey data. The study sampled 15,357 women who delivered in five last years. Besides delivery mode and education level, the study also used nine control variables: residence, age, marital, employment, parity, wealth, insurance, antenatal care, and birth type. The study employed a binary logistics regression.

Results

The results show women with secondary education (16.5% CS) are 2.174 times (AOR 2.174; 95% CI 1.095-4.316), and higher education (33% CS) are 3.241 (AOR 3.241; 95% CI 1.624-6.469) times more likely to deliver by CS than no-school education (4.4% CS). There was no significant difference between primary (9.1%) and no-education women. Apart from education, primiparous women, age 34-34 yr, attending antenatal care ≥4 times, non-poorest, having insurance, living in the city, and being unemployed also related to higher risk of CS.

Conclusion

Exceeded CS in Indonesia occurs mostly in higher education women. Higher education women were more likely to access more information and technology, therefore health promotion on healthy normal birth on social media or m-Health (mobile device-based health promotion) and involving health authorities at every level were suitable to reduce the overuse of the CS.

Early brain microstructural development among preterm infants requiring caesarean section versus those delivered vaginally

It is known that the rate of caesarean section (C-section) has been increasing among preterm births. However, the relationship between C-section and long-term neurological outcomes is unclear. In this study, we utilized diffusion tensor imaging (DTI) to characterize the association of delivery method with brain white matter (WM) microstructural integrity in preterm infants. We retrospectively analyzed the DTI scans and health records of preterm infants without neuroimaging abnormality on pre-discharge term-equivalent MRI. We applied both voxel-wise and tract-based analyses to evaluate the association between delivery method and DTI metrics across WM tracts while controlling for numerous covariates. We included 68 preterm infants in this study (23 delivered vaginally, 45 delivered via C-section). Voxel-wise and tract-based analyses revealed significantly lower fractional anisotropy values and significantly higher diffusivity values across major WM tracts in preterm infants delivered via C-section when compared to those delivered vaginally. These results may be partially, but not entirely, mediated by lower birth weight among infants delivered by C-section. Nevertheless, these infants may be at risk for delayed neurodevelopment and could benefit from close neurological follow up for early intervention and mitigation of adverse long-term outcomes.

Is Birth Method Associated with Sensory Hyperreactivity in Children 3-4 Years in an Upper-Middle-Income Country?

Background

Research has shown that pressure in the vaginal birth process aids the infant's neurophysiological adaption to extrauterine life, including their ability to regulate their responses to diverse sensory stimuli. As pressure is absent in elective caesarean section births, we hypothesised that these children may be at higher risk for developing sensory hyperreactivity (SHR), a sensory modulation difficulty which negatively impacts on the child's engagement in their occupations. This paper reports on a study which investigated associations between birth method and SHR.

Method

In this cross-sectional study, 91 children aged three and four years from various language, cultural, and socioeconomic groups were recruited and categorised based on birth method (caesarean section or vaginal birth). Caregivers of each child completed the Short Sensory Profile-2 and a demographic questionnaire. The prevalence of SHR between the birth method groups was compared.

Results

The prevalence of SHR was greater in the vaginal birth group (29%) than the caesarean section group (9%). Mothers in the vaginal birth group were younger (p ≤ 0.001), of lower-income level (p = 0.003), and more likely to be single (p = 0.037). During data collection with the vaginal birth group, comprehensibility of certain items in the Short Sensory Profile-2 proved challenging for many caregivers.

Conclusion

The statistically significant higher prevalence of SHR in the vaginal birth group supported a null hypothesis. However, the results are questioned due to the challenges related to data collection. Given this, the study supports the need for further investigation of how sociocultural and socioeconomic factors influence the assessment of SHR in the South African context.

Infertility and Risk of Autism Spectrum Disorder in Children

Importance

Previous studies on the risk of childhood autism spectrum disorder (ASD) following fertility treatment did not account for the infertility itself or the mediating effect of obstetrical and neonatal factors.

Objective

To assess the association between infertility and its treatments on the risk of ASD and the mediating effect of selected adverse pregnancy outcomes on that association.

Design, Setting, and Participants

This was a population-based cohort study in Ontario, Canada. Participants were all singleton and multifetal live births at 24 or more weeks' gestation from 2006 to 2018. Data were analyzed from October 2022 to October 2023.

Exposures

The exposure was mode of conception, namely, (1) unassisted conception, (2) infertility without fertility treatment (ie, subfertility), (3) ovulation induction (OI) or intrauterine insemination (IUI), or (4) in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).

Main Outcome and Measures

The study outcome was a diagnosis of ASD at age 18 months or older. Cox regression models generated hazard ratios (HR) adjusted for maternal and infant characteristics. Mediation analysis further accounted for the separate effect of (1) preeclampsia, (2) cesarean birth, (3) multifetal pregnancy, (4) preterm birth at less than 37 weeks, and (5) severe neonatal morbidity.

Results

A total of 1 370 152 children (703 407 male [51.3%]) were included: 1 185 024 (86.5%) with unassisted conception, 141 180 (10.3%) with parental subfertility, 20 429 (1.5%) following OI or IUI, and 23 519 (1.7%) following IVF or ICSI. Individuals with subfertility or fertility treatment were older and resided in higher-income areas; the mean (SD) age of each group was as follows: 30.1 (5.2) years in the unassisted conception group, 33.3 (4.7) years in the subfertility group, 33.1 (4.4) years in the OI or IUI group, and 35.8 (4.9) years in the IVF or ICSI group. The incidence rate of ASD was 1.93 per 1000 person-years among children in the unassisted conception group. Relative to the latter, the adjusted HR for ASD was 1.20 (95% CI, 1.15-1.25) in the subfertility group, 1.21 (95% CI, 1.09-1.34) following OI or IUI, and 1.16 (95% CI, 1.04-1.28) after IVF or ICSI. Obstetrical and neonatal factors appeared to mediate a sizeable proportion of the aforementioned association between mode of conception and ASD risk. For example, following IVF or ICSI, the proportion mediated by cesarean birth was 29%, multifetal pregnancy was 78%, preterm birth was 50%, and severe neonatal morbidity was 25%.

Conclusions and Relevance

In this cohort study, a slightly higher risk of ASD was observed in children born to individuals with infertility, which appears partly mediated by certain obstetrical and neonatal factors. To optimize child neurodevelopment, strategies should further explore these other factors in individuals with infertility, even among those not receiving fertility treatment.

Early brain microstructural development among preterm infants requiring caesarean section versus those delivered vaginally

It is known that the rate of caesarean section (C-section) has been increasing among preterm births. However, the relationship between C-section and long-term neurological outcomes is unclear. In this study, we utilized diffusion tensor imaging (DTI) to characterize the association of delivery method with brain white matter (WM) microstructural integrity in preterm infants. We retrospectively analyzed the DTI scans and health records of preterm infants without neuroimaging abnormality on pre-discharge term-equivalent MRI. We applied both voxel-wise and tract-based analyses to evaluate the association between delivery method and DTI metrics across WM tracts while controlling for numerous covariates. We included 68 preterm infants in this study (23 delivered vaginally, 45 delivered via C-section). Voxel-wise and tract-based analyses revealed significantly lower fractional anisotropy values and significantly higher diffusivity values across major WM tracts in preterm infants delivered via C-section when compared to those delivered vaginally. These results may be partially, but not entirely, mediated by lower birth weight among infants delivered by C-section. Nevertheless, these infants may be at risk for delayed neurodevelopment and could benefit from close neurological follow up for early intervention and mitigation of adverse long-term outcomes.

Association of caesarean delivery with offspring health outcomes in full-cohort versus sibling-comparison studies: a comparative meta-analysis and simulation study

BACKGROUND

Full-cohort and sibling-comparison designs have yielded inconsistent results about the impacts of caesarean delivery on offspring health outcomes, with the effect estimates from the latter being more likely directed towards the null value. We hypothesized that the seemingly conservative results obtained from the sibling-comparison design might be attributed to inadequate adjustment for non-shared confounders between siblings, particularly maternal age at delivery.

METHODS

A systematic review and meta-analysis was first conducted. PubMed, Embase, and the Web of Science were searched from database inception to April 6, 2022. Included studies (1) examined the association of caesarean delivery, whether elective or emergency, with offspring health outcomes; (2) simultaneously conducted full-cohort and sibling-comparison analyses; and (3) reported adjusted effect estimates with 95% confidence intervals (95% CIs). No language restrictions were applied. Data were extracted by 2 reviewers independently. Three-level meta-analytic models were used to calculate the pooled odds ratios (ORs) and 95% CIs for caesarean versus vaginal delivery on multiple offspring health outcomes separately for full-cohort and sibling-comparison designs. Subgroup analyses were performed based on the method of adjustment for maternal age at delivery. A simulation study was then conducted. The simulated datasets were generated with some key parameters derived from the meta-analysis.

RESULTS

Eighteen studies involving 21,854,828 individuals were included. The outcomes assessed included mental and behavioral disorders; endocrine, nutritional and metabolic diseases; asthma; cardiorespiratory fitness; and multiple sclerosis. The overall pooled OR for estimates from the full-cohort design was 1.14 (95% CI: 1.11 to 1.17), higher than that for estimates from the sibling-comparison design (OR = 1.08; 95% CI: 1.02 to 1.14). Stratified analyses showed that estimates from the sibling-comparison design varied considerably across studies using different methods to adjust for maternal age at delivery in multivariate analyses, while those from the full-cohort design were rather stable: in studies that did not adjust maternal age at delivery, the pooled OR of full-cohort vs. sibling-comparison design was 1.10 (95% CI: 0.99 to 1.22) vs. 1.06 (95% CI: 0.85 to 1.31), in studies adjusting it as a categorical variable, 1.15 (95% CI: 1.11 to 1.19) vs. 1.07 (95% CI: 1.00 to 1.15), and in studies adjusting it as a continuous variable, 1.12 (95% CI: 1.05 to 1.19) vs. 1.12 (95% CI: 0.98 to 1.29). The severe underestimation bias related to the inadequate adjustment of maternal age at delivery in sibling-comparison analyses was fully replicated in the simulation study.

CONCLUSIONS

Sibling-comparison analyses may underestimate the association of caesarean delivery with multiple offspring health outcomes due to inadequate adjustment of non-shared confounders, such as maternal age at delivery. Thus, we should be cautious when interpreting the seemingly conservative results of sibling-comparison analyses in delivery-related studies.

Current Knowledge About the Impact of Maternal and Infant Nutrition on the Development of the Microbiota-Gut-Brain Axis

The prenatal and early postnatal periods are stages during which dynamic changes and the development of the brain and gut microbiota occur, and nutrition is one of the most important modifiable factors that influences this process. Given the bidirectional cross talk between the gut microbiota and the brain through the microbiota-gut-brain axis (MGBA), there is growing interest in evaluating the potential effects of nutritional interventions administered during these critical developmental windows on gut microbiota composition and function and their association with neurodevelopmental outcomes. We review recent preclinical and clinical evidence from animal studies and infant/child populations. Although further research is needed, growing evidence suggests that different functional nutrients affect the establishment and development of the microbiota-gut-brain axis and could have preventive and therapeutic use in the treatment of neuropsychiatric disorders. Therefore, more in-depth knowledge regarding the effect of nutrition on the MGBA during critical developmental windows may enable the prevention of later neurocognitive and behavioral disorders and allow the establishment of individualized nutrition-based programs that can be used from the prenatal to the early and middle stages of life.