The role of obstetric adversities in neurodevelopmental conditions: A sibling study.

This study looked at birth complications in children with autism and ADHD compared to their siblings and other children. Researchers found that children with autism or ADHD had more problems in their first 4 weeks of life than their brothers and sisters or other children without these conditions. The problems weren't during pregnancy, but after birth. Having several small problems together seemed more important than any single major problem.

This Spanish case-control sibling study examined obstetric complications in 238 participants including children with autism spectrum disorder (ASD), ADHD, co-occurring ASD+ADHD, their unaffected siblings, and comparison controls. Using a sibling design to control for familial confounding, researchers found that children with neurodevelopmental conditions experienced significantly more neonatal complications (first 4 weeks of life) compared to both their unaffected siblings and control groups. The association remained significant even after controlling for shared genetic and environmental factors within families. Importantly, cumulative neonatal complications rather than specific individual factors were associated with increased likelihood of neurodevelopmental diagnoses, highlighting the neonatal period as a critical window of vulnerability for neurodevelopmental outcomes.

Findings suggest enhanced monitoring during the neonatal period may be beneficial for early identification of neurodevelopmental risk. Cumulative approach to assessing neonatal complications may be more clinically relevant than focusing on individual factors. Results support early intervention frameworks targeting the neonatal period as a critical developmental window.

Single-site study from Spain limits generalizability. Relatively small sample size (238 participants) may affect statistical power. Retrospective data collection through parental interviews subject to recall bias. Cross-sectional design prevents causal inference establishment.

Neurodevelopmental conditions (NDC) are highly heritable. Obstetric complications (OC) have been studied as potential predictors for NDC, although results are inconsistent. Inconsistencies might be related to biases such as family confounders. While some studies using sibling and twin designs have examined the association between OC and NDC, this body of research remains limited, and findings to date remain inconsistent.

We used a case-control sibling study including children aged 6-17 years across five groups: those diagnosed with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), co-occurring ASD + ADHD, their unaffected siblings and a comparison group without NDC. For analytic purposes, we created a combined NDC group including all individuals with ASD, ADHD or both. Participants were recruited between 2021 and 2022 from a tertiary hospital in Spain. We examined the association of NDC and OC using single predictors and cumulative OC.

The study adheres to the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines. A total of 238 participants were included (NDC = 117, unaffected siblings = 82, comparison group = 39). We found that NDC individuals showed more neonatal complications than the comparison group (β = 1.73, 95% CI = 1.00-2.98, p = 0.04), which remained significant in the sibling analysis (β = 1.43, 95% CI = 1.02-2.00, p = 0.04). This study supports that the cumulative neonatal complications, rather than specific factors, are associated with increased likelihood of being diagnosed with NDC, beyond familial confounding.

Results highlight the neonatal period as a relevant window of vulnerability.Lay AbstractThis study examined the association between complications during pregnancy and autism, attention-deficit/hyperactivity disorder and the combination of both conditions. We compared children with these conditions and their siblings, as well as a group comparison without diagnosed neurodevelopmental disorders. We gathered information through parents' interviews. We found that children with autism or attention-deficit/hyperactivity disorder presented more problems in the first 4 weeks of the child's life than their siblings and the group of comparison.

We did not find that children with these conditions present more complications during pregnancy. In addition, we observed that the probability of being diagnosed with these conditions is increased due to cumulative problems rather than specific problems.