Partner smoking and maternal cotinine during pregnancy: implications for negative control methods

Area of Science:

• Environmental Health
• Reproductive Health
• Biomarkers of Exposure

Background:

• Investigating intrauterine tobacco exposure effects often compares maternal and partner smoking impacts.
• A key assumption is that passive smoke exposure from partners during pregnancy is negligible.
• This study biochemically assesses tobacco exposure in pregnant women to evaluate this assumption.

Purpose of the Study:

• To evaluate the assumption that passive smoking from a partner during pregnancy has minimal effects.
• To determine the validity of using partner smoking as a negative control in research on intrauterine tobacco effects.

Main Methods:

• Measured first-trimester cotinine levels in 3928 pregnant women from the Avon Longitudinal Study of Parents and Children.
• Compared median cotinine values based on maternal smoking intensity.
• Assessed cotinine levels in non-smoking women relative to their partner's smoking status and intensity.

Main Results:

• Cotinine levels were significantly higher in smoking mothers compared to non-smokers (medians 900-5362 ng/ml vs. 20 ng/ml).
• Non-smoking women with smoking partners had low cotinine levels (medians 34-69 ng/ml) compared to those with non-smoking partners (12 ng/ml).
• Biochemical measures indicate minimal tobacco exposure from partner smoking in non-smoking pregnant women.

Conclusions:

• Biochemically assessed tobacco exposure from partner smoking was low in non-smoking pregnant women.
• This supports the validity of using maternal partner smoking as a negative control.
• The findings strengthen methodologies for studying intrauterine tobacco exposure effects.