| Risk factor |
OR |
95% CI |
Adjustments |
| Maternal age |
|
|
Year of birth, parity, smoking, previous
miscarriages, sub fertility |
| <20 |
0.98 |
0.85-1.14 |
|
| 20-24 |
0.96 |
0.90-1.02 |
|
| 25-29 |
0.99 |
0.94-1.04 |
|
| 30-34 |
1.05 |
0.99-1.11 |
|
| 35-39 |
1.03 |
0.95-1.11 |
|
| 40-44 |
0.89 |
0.73-1.08 |
|
| ≥45 |
1.18 |
(0.49-2.86) |
|
| Parity |
|
|
Year of birth, maternal age, smoking,
previous miscarriages, sub fertility |
| 1 |
1.00 |
0.95-1.06 |
|
| 2 |
1.00 |
0.95-1.06 |
|
| 3 |
0.99 |
0.91-1.05 |
|
| ≥4 |
1.08 |
0.99-1.19 |
|
| Smoking |
|
|
Year of birth, maternal age, parity,
previous miscarriages, sub fertility |
| None |
1.00 |
reference |
|
| <10 cigarettes/day |
0.99 |
0.92-1.07 |
|
| ≥10 cigarettes/day |
1.08 |
0.99-1.19 |
|
| Previous miscarriages |
|
|
Year of birth, maternal age, parity,
smoking, sub fertility |
| None |
1.00 |
reference |
|
| 1 |
0.96 |
0.88-1.03 |
|
| 2 |
1.02 |
0.87-1.19 |
|
| ≥3 |
1.06 |
0.82-1.38 |
|
| Sub fertility (years of
unwanted childlessness) |
|
|
Year of birth, maternal age, parity, smoking,
previous miscarriages |
| None |
1.00 |
reference |
|
| 1 |
1.04 |
0.87-1.24 |
|
| 2 |
0.94 |
0.72-1.15 |
|
| 3 |
0.91 |
0.69-1.20 |
|
| 4 |
1.13 |
0.80-1.55 |
|
| ≥5 |
1.18 |
0.96-1.44 |
|
| Body mass index |
|
|
Year of birth, previous miscarriages,
years of unwanted childlessness |
| <19.8 |
0.97 |
0.82-1.14 |
|
| 19.8-25.9 |
1.00 |
reference |
|
| 26.0-29.9 |
1.02 |
0.89-1.16 |
|
| 30.0-39.9 |
1.01 |
0.85-1.21 |
|
| ≥40 |
0.97 |
0.49-1.95 |
|
For maternal age and parity, each subgroup was compared with all other subgroups. |