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  • Writer's pictureKirk Hartley

Major New Study Explicitly Identifies Deformed Limbs, Heart Defects, and Other Birth Defects Cause

Smoking imposes a staggering human and financial toll through the cancers it causes. Less well defined and known are the human and financial costs of birth defects caused by smoking during pregnancy. This major new study from the UK helps to define the burden as it comprehensively reviews 50 years of scientific papers, and presents the increased risk levels for numerous, severe birth defects. Here are key excerpts from the ScienceDaily summary of the paper, followed by the more technically worded "results" section of the abstract for the paper. The results section provides the specific odds ratios, which some courts consider important to product liability claims. The full paper is here, and is an "open access" paper, meaning that the full text and tables are available from the journal’s website at the link.

"The study, published July 12 in Human Reproduction Update, is the first comprehensive review to identify the specific birth defects (malformations) most associated with smoking.


The authors examined a total of 172 research papers published over the last 50 years, which looked at a combined total of 174,000 cases of malformation alongside 11.7 million controls. The risk was increased by 26% for having a baby with missing or deformed limbs, 28% for clubfoot, 27% for gastrointestinal defects, 33% for skull defects, 25% for eye defects, and 28% for cleft lip/palate. The greatest increase in risk (50%) was for a condition called gastroschisis, where parts of the stomach or intestines protrude through the skin.

The research authors recommend that public health guidance should now be more explicit about the specific malformations associated with maternal smoking, in order to try and reduce the numbers of pregnant women who smoke."


RESULTS Significant positive associations with maternal smoking were found for: cardiovascular/heart defects [OR 1.09, 95% confidence interval (CI) 1.02–1.17]; musculoskeletal defects (OR 1.16, 95% CI 1.05–1.27); limb reduction defects (OR 1.26, 95% CI 1.15–1.39); missing/extra digits (OR 1.18, 95% CI 0.99–1.41); clubfoot (OR 1.28, 95% CI 1.10–1.47); craniosynostosis (OR 1.33, 95% CI 1.03–1.73); facial defects (OR 1.19, 95% CI 1.06–1.35); eye defects (OR 1.25, 95% CI 1.11–1.40); orofacial clefts (OR 1.28, 95% CI 1.20–1.36); gastrointestinal defects (OR 1.27, 95% CI 1.18–1.36); gastroschisis (OR 1.50, 95% CI 1.28–1.76); anal atresia (OR 1.20, 95% CI 1.06–1.36); hernia (OR 1.40, 95% CI 1.23–1.59); and undescended testes (OR 1.13, 95% CI 1.02–1.25). There was a reduced risk for hypospadias (OR 0.90, 95% CI 0.85–0.95) and skin defects (OR 0.82, 0.75–0.89). For all defects combined the OR was 1.01 (0.96–1.07), due to including defects with a reduced risk and those with no association (including chromosomal defects).

CONCLUSIONS Birth defects that are positively associated with maternal smoking should now be included in public health educational materials to encourage more women to quit before or during pregnancy.

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