Smoking in Pregnancy and Child Brain Development

Smoking during pregnancy produces significant and diverse effects on prenatal development.

These adverse effects include dysfunction in prenatal and early childhood brain development.

Hanan El Marroun and colleagues from the Netherlands recently published an important childhood brain imaging study of smoking during pregnancy.

One hundred and thirteen children exposed to tobacco during pregnancy were compared to a control group of unexposed children.

Both groups of children between 6 and 8 years of age were compared on a variety of measures including:

• Nonverbal IQ
• Birth weight and gestational age
• Child Behavior Checklist scores
• Structural brain imaging measures using MRI structural brain imaging

The key findings from this study included the following:

• Birth weight: exposed infants had a significantly lower mean birth weight than non-smoking exposed infants 3194 grams vs 3475 grams (7.04 pounds vs 7.66 pounds)
• Total brain volumes: exposed children showed smaller total brain volumes and smaller brain white matter volumes
• Brain cortex measures: exposed children showed thinner brain cortex measures in multiple brain regions including frontal, temporal and parietal regions
• Behavioral and emotional problems: exposed children had higher measures of mood and anxiety problems at 6 to eight years

An additional important finding was a statistically significant correlation between mood symptoms and thinning of cortical thickness in the superior frontal cortex and the precentral cortex regions.

Children of women who stopped smoking immediately after learning of pregnancy displayed similar brain development as the non-exposed children.

Although key covariates were controlled in this study, the authors do note they cannot rule out a potential contribution of smoking epiphenomenon in their findings. Such potential epiphenomenon linked to the smoking group could include higher parental psychopathology, effect of other substances and differences in paternal nutritional profiles.

This study does support early pregnancy identification in smoking women and aggressive smoking cessation treatment efforts.

Readers with more interest in this study can access the free full-text manuscript by clicking on the PMID link below.

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El Marroun H, Schmidt MN, Franken IH, Jaddoe VW, Hofman A, van der Lugt A, Verhulst FC, Tiemeier H, & White T (2014). Prenatal tobacco exposure and brain morphology: a prospective study in young children. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 39 (4), 792-800 PMID: 24096296