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Selection and the effect of prenatal smoking
1Department of Health Policy and Management, University of Georgia, Athens, GA, USA. afertig@uga.edu
Health Economics
|March 26, 2009
Summary
Prenatal smoking significantly impacts infant health, but some effects may be due to other maternal factors. This study suggests that selection effects explain up to 50% of the observed association between smoking and adverse birth outcomes.
Area of Science:
- Reproductive Health
- Epidemiology
- Public Health
Background:
- The causal link between prenatal smoking and infant health is debated.
- Maternal characteristics correlated with smoking may confound observed outcomes.
- Understanding selection bias is crucial for accurate risk assessment.
Purpose of the Study:
- To quantify the role of selection bias in the association between prenatal smoking and infant health outcomes.
- To investigate how changes in maternal knowledge about smoking harms affect this association over time.
Main Methods:
- Utilized three British birth cohort studies with varying maternal awareness of smoking risks.
- Analyzed the probability of low birth weight, conditional on gestation.
- Compared the estimated effect of smoking across different time periods (1958 vs. 2000).
Main Results:
- The estimated effect of smoking on low birth weight (conditional on gestation) more than doubled between 1958 and 2000.
- Selection effects appear to account for up to 50% of the current association between prenatal smoking and adverse birth outcomes.
Conclusions:
- Selection bias plays a substantial role in the observed relationship between prenatal smoking and infant health.
- Increasing awareness of smoking harms may have amplified the apparent effect of smoking through selection mechanisms.
