Maternal smoking during pregnancy and offspring risk of intellectual disability: a UK-based cohort study

Area of Science:

• Reproductive Health
• Developmental Neuroscience
• Epidemiology

Background:

• Observational studies suggest maternal smoking during pregnancy is associated with offspring intellectual disability (ID).
• The causal nature of this association remains uncertain, with potential for unmeasured confounding.
• Clarifying this relationship is crucial for public health guidance and interventions.

Purpose of the Study:

• To investigate the causal relationship between maternal smoking during pregnancy and offspring intellectual disability (ID).
• To differentiate between a true causal effect and confounding factors in the observed association.
• To provide evidence-based conclusions for prenatal care recommendations.

Main Methods:

• Utilized a UK-based prospective birth cohort (Avon Longitudinal Study of Parents and Children) with 13,479 children.
• Assessed maternal smoking at 18 weeks' gestation and offspring ID using linked health and education records.
• Employed confounder-adjusted logistic regression and a negative control analysis comparing maternal and partner smoking.

Main Results:

• Observational analysis showed no significant association between maternal smoking and offspring ID (OR 0.75-0.97).
• Negative control analysis comparing maternal and partner smoking yielded comparable, non-significant effect estimates (OR 0.94).
• Results indicate that biases affecting both exposures likely explain observed associations.

Conclusions:

• The findings do not support a causal effect of maternal smoking during pregnancy on offspring intellectual disability.
• The observed associations are likely attributable to confounding factors or biases common to both maternal and partner smoking.
• This study underscores the importance of rigorous methodology in establishing causality in observational research.