Pregnant Smoking Has Another Bad Effect

Smoking while pregnant impacts genetics

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Can smoking while pregnant cause genetic changes which make the child more at risk for asthma development? Researchers answer with a resounding, "yes."

Research shows that a process called DNA methylation alters a gene's normal role and impacts the AXL gene in children whose mothers smoke while they are pregnant. The AXL gene is also associated with many cancers and immune responses.

"Pregnant women should quit smoking now."

Carrie Breton, ScD, assistant professor of preventive medicine at The Keck School of Medicine of the University of Southern California (USC) in Los Angeles, explained that a recent study shows the need to understand more about environmental exposures that affect DNA methylation patterns prior to birth.

Imprinted genes, in which one gene is "chosen" from one of the two parents, appear to be particularly subject to change from in utero smoking.

In utero and early life exposures are particularly important, given that we know when non-genetic changes in genes occur. 

The Study

  • Researchers had mothers and grandmothers of 173 children participants of the Early Asthma Risk Factors Study (EARS) fill out a detailed questionnaire
  • DNA samples collected from cheek cells of mothers and children were evaluated
  • Children exposed to maternal smoking in utero had a 2.3 percent increase in DNA methylation in AXL
  • Grandmaternal smoking was not significantly associated with AXL methylation in either the mother or the child
  • DNA methylation of AXL and its association with in utero exposure to smoking was stronger in girls than in boys
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Review Date: 
May 13, 2011
Last Updated:
May 26, 2011