A Comparison of Measured Airborne and Self-Reported Secondhand Smoke Exposure in the MADRES Pregnancy Cohort Study

Abstract

Background: Secondhand smoke (SHS) exposure during pregnancy is associated with several adverse birth outcomes, including reduced birthweight and preterm birth. Questionnaires are commonly used to assess SHS exposure; however, the wording of questions and their ability to capture true exposure can vary, limiting researchers’ ability to harmonize SHS measures. Therefore, we compared the association of SHS self-reported exposure in the MADRES pregnancy cohort with measurements of SHS in particulate matter (PM₂.₅) personal samples collected in the 3rd trimester. Methods: We measured SHS on 48-hour integrated personal PM₂.₅ Teflon filters collected from 204 pregnant women using optical transmissometry. Self-reported SHS related to presence, intensity, and duration of exposure was ascertained via a 3rd trimester questionnaire and an exit survey at the time of personal monitoring. Descriptive statistics were calculated for SHS measures overall and by key demographics and environmental factors. Analysis of variance tests were conducted to test group differences in SHS concentrations by self-reported SHS exposure. Results: Participants were predominately Hispanic (81%), with a mean (SD) age of 28.2 (6.0) years. Geometric mean (SD) personal SHS concentrations were 0.14 (9.41) µg/m³. There was a significant difference in mean SHS by education (p = 0.015), with participants with lower education having higher measured SHS. Mean SHS concentrations differed by reported time with windows open (none/a little of the time: 0.10 µg/m³ vs. most/all of the time: 0.19 µg/m³; p = 0.047). There was no association between measured SHS and self-reported SHS exposure; however, asking about the number of smokers nearby in the 48-hour monitoring period was most correlated with measured SHS (Two+ smokers: 0.30 µg/m³ vs. One: 0.12 µg/m³ and Zero: 0.15 µg/m³; p = 0.230). Conclusion: Overall, self-reported SHS exposure was not associated with measured airborne SHS in personal PM₂.₅ samples.