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)

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