Smoking Is Associated with, but Does Not Cause, Depressed Mood in Pregnancy – A Mendelian Randomization Study
2011

Smoking and Depressed Mood in Pregnancy

Sample size: 6294 publication 10 minutes Evidence: moderate

Author Information

Author(s): Lewis Sarah J., Araya Ricardo, Davey Smith George, Freathy Rachel, Gunnell David, Palmer Tom, Munafò Marcus

Primary Institution: University of Bristol

Hypothesis

Does smoking during pregnancy cause depressed mood, or is the association due to confounding factors?

Conclusion

The study found that smoking does not cause depressed mood during pregnancy, but may be used as a self-medication strategy by women experiencing low mood.

Supporting Evidence

  • Women who smoked prior to pregnancy were 2.5 times more likely to report depressed mood.
  • The T allele of the rs1051730 variant was associated with lower levels of reported depressed mood.
  • Smoking cessation was linked to a reduction in reported low mood among pregnant women.

Takeaway

Women who smoke during pregnancy might feel less depressed, but smoking doesn't actually cause depression; it could be a way to cope with feeling sad.

Methodology

The study used Mendelian randomization to analyze the association between a genetic variant related to smoking and depressed mood in pregnant women.

Potential Biases

Potential reporting bias in self-reported smoking status and mood assessments.

Limitations

The study relied on self-reported measures of smoking and mood, and did not conduct psychiatric interviews for depression.

Participant Demographics

Pregnant women from Bristol, England, with a sample size of 6294.

Statistical Information

P-Value

0.034

Confidence Interval

95% CI 0.72 to 0.99

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1371/journal.pone.0021689

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