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Table 2 Multiple-imputation analysis of the relationship between body-mass index, smoking and alcohol intake with risk of miscarriage excluding induced abortions (n = 23,503)

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 1204 278 (23.1) 1.08 (0.96, 1.22), 0.2 1.07 (0.94, 1.21), 0.3 1.07 (0.94, 1.21), 0.3
Normal weight 13,505 2918 (21.6) Ref Ref Ref
Overweight 5506 1253 (22.8) 1.05 (0.98, 1.12), 0.1 1.02 (0.96, 1.09), 0.5 1.03 (0.96, 1.09), 0.4
Obese 3288 868 (26.4) 1.22 (1.14, 1.32), < 0.001 1.13 (1.05, 1.21), 0.001 1.14 (1.06, 1.23), < 0.001
Smoking Never smoker 13,071 2749 (21.0) Ref Ref Ref
Former smoker 5712 1326 (23.2) 1.10 (1.03, 1.17), 0.003 0.99 (0.94, 1.06), 0.9 0.98 (0.92, 1.04), 0.5
< 10 cigarettes per day 1814 442 (24.4) 1.16 (1.05, 1.28), 0.003 1.02 (0.93, 1.13), 0.6 1.00 (0.91, 1.10), 0.9
10–19 cigarettes per day 1404 397 (28.3) 1.37 (1.24, 1.51), < 0.001 1.13 (1.02, 1.25), 0.02 1.09 (0.98, 1.21), 0.1
20 or more cigarettes per day 889 244 (27.4) 1.34 (1.19, 1.51), < 0.001 1.07 (0.94, 1.21), 0.3 1.03 (0.91, 1.17), 0.6
Unknown amount of smoking 613 159 (25.9) 1.30 (1.13, 1.50), < 0.001 1.06 (0.90, 1.25), 0.5 1.02 (0.86, 1.22), 0.8
Alcohol intake Low risk drinker 19,957 4544 (22.8) Ref Ref Ref
Non-drinker 2700 513 (19.0) 0.81 (0.74, 0.89), < 0.001 0.82 (0.75, 0.89), < 0.001 0.81 (0.74, 0.89), < 0.001
Risky drinker 846 260 (30.7) 1.36 (1.22, 1.52), < 0.001 1.15 (1.03, 1.28), 0.02 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)