Maternal Smoking During Pregnancy and Risk of Autism Spectrum Disorder in Offspring: A Systematic Review and...

Area of Science:

• Neurodevelopmental disorders
• Prenatal environmental exposures
• Autism Spectrum Disorder (ASD) etiology

Background:

• Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with known genetic influences.
• Prenatal environmental factors are increasingly recognized as potential contributors to ASD.
• The association between maternal smoking during pregnancy and ASD risk is not well-established.

Purpose of the Study:

• To systematically review and meta-analyze existing observational studies on maternal smoking during pregnancy and ASD.
• To quantify the risk of ASD in offspring exposed to maternal smoking in utero.
• To provide evidence-based conclusions regarding this potential environmental risk factor.

Main Methods:

• Systematic review and meta-analysis adhering to PRISMA 2020 guidelines.
• Comprehensive literature search across multiple major scientific databases up to September 2025.
• Pooled relative risks (RR) using a random-effects model for studies evaluating maternal active smoking and ASD diagnosis.

Main Results:

• Twenty-one studies comprising millions of mother-child pairs were included.
• The overall pooled relative risk for ASD associated with maternal smoking was 1.01 (95% CI: 0.95-1.08), indicating no statistically significant association.
• Subgroup analyses, sensitivity analyses, and publication bias assessments confirmed the robustness of these findings.

Conclusions:

• Maternal smoking during pregnancy is not associated with an increased risk of autism spectrum disorder in offspring.
• Despite this finding, smoking cessation during pregnancy is strongly recommended due to other significant, established adverse fetal effects.
• Further research may explore other prenatal exposures and their complex interplay with genetic factors in ASD development.