| Study | Population | Study period | Smoking status | Relative risk (95% confidenceinterval) | Adjustment factors |
|---|---|---|---|---|---|
| Hadley et al. 1990 | Black women with singleton
pregnancies Cases: 133 women with PPROM Controls: 133 pregnant women (not "high risk") United States | Not reported | Nonsmokers | 1.0 | Matched for maternal age, parity, gestational age Adjustment for previous PPROM, fundal placental location |
| Smokers (>10 cigarettes/day) | 2.6 (1.6-4.5) | ||||
| Harger et al. 1990 | Cases: 341 women with singleton
pregnancies and PPROM Controls: 253 pregnant women with intact membranes at 37 weeks' gestation United States | 1982-1983 | Nonsmokers | 1.0 | None |
| Stopped smoking during pregnancy | 1.6 (0.8-3.3) | ||||
| Continuing smokers | 2.1 (1.4-3.1) | ||||
| Williams et al. 1992 | Cases: 307 women with singleton
pregnancies and PPROM Controls: 2,252 women with term deliveries and no PROM United States | 1977-1980 | Never smoked | 1.0 | Race, education, age, welfare status, martial status, marijuana and alcohol use, parity, previous spontaneous or therapeutic abortion, cervical incompetence, bleeding during pregnancy, body mass index, coffee consumption |
| Stopped smoking before conception | 1.4 (0.9-2.0) | ||||
| Stopped smoking during first trimester | 1.6 (0.8-2.9) | ||||
| Nonsmokers during pregnancy | 1.0 | ||||
| Smokers throughout pregnancy | 2.2 (1.4-3.5) | ||||
| Smokers at some time during pregnancy | 1.6 (1.1-2.4) | ||||
| 1-9 cigarettes/day | 1.8 (1.1-2.8) | ||||
| 10-19 cigarettes/day | 1.5 (0.9-2.4) | ||||
| > 20 cigarettes/day | 1.7 (1.0-2.6) | ||||
| Ekwo et al. 1993 | Cases: 184 women with
PPROM Controls: 184 pregnant women United States | 1985-1990 | No smoke exposure | 1.0 | Matched for maternal age, parity, race |
| Passive smokers only | 1.0 (0.6-1.8) | ||||
| Active smokers only | 4.2 (1.8-10.0) | ||||
| Active and passive smokers | 2.1 (1.2-3.5) | ||||
| Spinillo et al. 1994d | Cases: 138 women with PPROM (24-35
weeks' gestation) Controls: 267 women with term pregnancies Italy | 1988-1992 | Nonsmokers | 1.0 | Previous term and preterm deliveries, social class, prepregnancy body mass index, bleeding during pregnancy, incompetent cervix, preeclampsia, low hematocrit on hospital admission for delivery, documented cervicovaginal infection during pregnancy |
| Smokers | 1.9 (1.1-3.2) | ||||
| <10 cigarettes/day | 1.1 (0.5-2.2) | ||||
| >10 cigarettes/day | 4.0 (1.9-8.8) |
From: Chapter 3. Health Consequences of Tobacco Use Among Women
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