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Table 3 Multiple-imputation analysis of the relationship between body-mass index, smoking and alcohol intake with risk of miscarriage including 50% of induced abortions (n = 26,592)

From: Pre-pregnancy lifestyle characteristics and risk of miscarriage: the Australian Longitudinal Study on Women’s Health

Exposure Exposure category N N cases (%) Unadjusted RR (95% CI), p-value Adjusted RR (95% CI) a, p-value Adjusted RR
(95% CI) b, p-value
Body-mass index Underweight 1412 278 (19.7) 1.06 (0.94, 1.20), 0.3 1.05 (0.93, 1.19), 0.4 1.05 (0.93, 1.19), 0.4
Normal weight 15,383 2918 (19.0) Ref Ref Ref
Overweight 6140 1253 (20.4) 1.06 (1.00, 1.14), 0.07 1.04 (0.97, 1.10), 0.3 1.04 (0.97, 1.10), 0.3
Obese 3657 868 (23.7) 1.24 (1.15, 1.34), < 0.001 1.15 (1.07, 1.24), < 0.001 1.16 (1.08, 1.25), < 0.001
Smoking Never smoker 14,267 2749 (19.3) Ref Ref Ref
Former smoker 6400 1326 (20.7) 1.09 (1.02, 1.16), 0.01 0.98 (0.93, 1.05), 0.6 0.97 (0.91, 1.03), 0.3
< 10 cigarettes per day 2247 442 (19.7) 1.09 (0.98, 1.20), 0.1 0.98 (0.88, 1.08), 0.6 0.96 (0.87, 1.06), 0.4
10–19 cigarettes per day 1746 397 (22.7) 1.27 (1.14, 1.41), < 0.001 1.09 (0.98, 1.21), 0.1 1.06 (0.95, 1.18), 0.3
20 or more cigarettes per day 1120 244 (21.8) 1.23 (1.09, 1.39), 0.001 1.02 (0.90, 1.16), 0.7 0.99 (0.87, 1.13), 0.9
Unknown amount of smoking 812 159 (19.6) 1.17 (1.01, 1.35), 0.04 1.04 (0.89, 1.22), 0.6 1.02 (0.86, 1.20), 0.8
Alcohol intake Low risk drinker 22,612 4544 (20.1) Ref Ref Ref
Non-drinker 2898 513 (17.7) 0.83 (0.76, 0.92), < 0.001 0.84 (0.77, 0.92), < 0.001 0.83 (0.76, 0.91), < 0.001
Risky drinker 1082 260 (24.0) 1.27 (1.13, 1.42), < 0.001 1.13 (1.01, 1.27), 0.03 1.13 (1.01, 1.27), 0.04
  1. a Adjusted for age, marital status, educational level, area of residence, occupation, managing on income and number of previous pregnancies
  2. b Adjusted for age, marital status, educational level, area of residence, occupation, managing on income, number of previous pregnancies, in addition to the other lifestyle factors of interest (body-mass index, smoking and alcohol intake)