Table 1.
Measurements of maternal smoking during pregnancy
| Maternal smoking parameter | No. of women with data available for estimate | No. of women who smoked by measure | Value among smokers |
|---|---|---|---|
| Mean (SD) | |||
| Ever smoked during pregnancy (Model 1A) | 981 | 296 (30%) | |
| Number of cigarettes per day | |||
| Average | 981 | 296a | 11.5 (7.8) |
| Square root of average (Model 2A) | 3.0 (1.3) | ||
| Trimester 1–2 self-report (Model 3A1) – square root | 909 | 266b | 3.0 (1.1) |
| Trimester 3 self-report (Model 3A2) – square root | 909 | 266b | 2.9 (1.1) |
| Ever positive cotinine during pregnancy (Model 1B) | 959 | 315 (33%) | |
| Cotinine value | |||
| Average | 959 | 315c | 34.9 (32.5) |
| Log of average (Model 2B) | 3.1 (1.2) | ||
| Trimester 1–2 cotinine (Model 3B1) – log | 909 | 292d | 2.7 (1.0) |
| Trimester 3 cotinine (Model 3B2) – log | 909 | 292d | 3.0 (0.9) |
| Combined self-report/cotinine | |||
| Trimester 1/2 (Model 4A) | 909 | 307e | 21.8 (8.5) |
| Trimester 3 (Model 4B) | 909 | 264e | 20.9 (9.2) |
a
Sub-sample of women who ever self-reported smoking in pregnancy.
b
Sub-sample of women with more than one visit and with evidence of smoking by self-report.
c
Sub-sample of women with at least one cotinine value indicating smoking.
d
Sub-sample of women with more than one visit and with evidence of smoking by cotinine.
e
Sub-sample of women with self-report and cotinine data and evidence of smoking in relevant trimester.