Table 1.
Saliva cotinine concentrations according to self-reported active and passive smoking status during pregnancy.
| Tobacco Smoke Exposure * | n | Geometric Mean (ng/mL) | 95% CI (ng/mL) |
|---|---|---|---|
| Non-smokers | |||
| 1st trimester (n = 1505; missing = 231) | 1274 | 1.14 | 1.06–1.22 |
| 2nd trimester (n = 1356; missing = 554) | 802 | 1.10 | 1.01–2.00 |
| 3rd trimester (n = 1273; missing = 293) | 980 | 1.15 | 1.07–1.24 |
| Smokers | |||
| 1st trimester (n = 196; missing = 39) | 157 | 78.77 | 65.53–94.68 |
| 2nd trimester (n = 142; missing = 36) | 106 | 98.48 | 81.83–118.52 |
| 3rd trimester (n = 122; missing = 23) | 99 | 85.84 | 69.75–105.65 |
| Passive smokers ** | |||
| 1st trimester husband/partner smoking (n = 423; missing = 61) | 362 | 1.84 | 1.56–2.16 |
| 2nd trimester husband/partner smoking (n = 338; missing = 148) | 190 | 2.08 | 1.66–2.60 |
| 3rd trimester husband/partner smoking (n = 325; missing = 82) | 243 | 1.89 | 1.55–2.31 |
| 1st trimester ETS exposure (n = 614; missing = 99) | 515 | 1.55 | 1.36–1.76 |
| 2nd trimester ETS exposure (n = 236; missing = 106) | 130 | 3.24 a | 2.34–4.49 |
| 3rd trimester ETS exposure (n = 204; missing = 65) | 139 | 3.42 b | 2.57–4.56 |
| 1st trimester smoking allowed at home (n = 239; missing = 30) | 209 | 2.86 | 2.27–3.61 |
| 2nd trimester smoking allowed at home (n = 185; missing = 80) | 105 | 3.53 | 2.51–4.96 |
| 3rd trimester smoking allowed at home (n = 181; missing = 45) | 136 | 3.19 | 2.37–4.28 |
a Environmental tobacco smoke (ETS) 1st trimester vs. ETS 2nd trimester, p < 0.001 (nonparametric Wilcoxon test); b ETS 1st trimester vs. ETS 3rd trimester, p < 0.001 (nonparametric Wilcoxon test); * the numbers might not sum up to the total sample size as some missing data were observed (described in the Materials and Methods section of the manuscript); ** restricted to non-smokers; CI: confidence interval.