Table 1.
Background characteristics among 296 preeclampsia cases and 580 controls. Odds ratios (OR) and 95% confidence intervals (CI) were obtained from univariate logistic regression models.
| Characteristics | Mean/Median (min, max) | OR | 95% CI | |
|---|---|---|---|---|
| Cases | Controls | |||
| Maternal birth year | 1973/1974 (1952, 1992) |
1973/1973 (1955, 1993) |
- a | - |
| Calendar-year of childbirth | 2004/2005 (1995, 2009) |
2003/2004 (1995, 2009) |
- | - |
| Maternal age at childbirth (year) | 30/30 (15, 44) |
29/29 (15, 42) |
- | - |
| Characteristics | n (%) | OR | 95% CI | |
| Cases | Controls | |||
| BMI in early pregnancy (kg/m2) | ||||
| <20 | 21 (8.4) | 60 (11.9) | 0.76 | 0.44–1.30 |
| 20–<25 | 132 (53.0) | 286 (56.9) | 1.00 | Ref |
| 25–<30 | 52 (20.9) | 109 (21.7) | 1.03 | 0.70–1.53 |
| ≥30 | 44 (17.7) | 48 (9.5) | 1.99 | 1.26–3.14 |
| Missing | 47 | 77 | ||
| Parity | ||||
| 1 | 228 (77.0) | 273 (47.1) | 3.77 | 2.75–5.17 |
| ≥2 | 68 (23.0) | 307 (52.9) | 1.00 | Ref |
| Gestational age (weeks) | ||||
| <34 | 13 (4.4) | 2 (0.3) | 18.9 | 4.23–84.6 |
| 34–<37 | 89 (30.1) | 13 (2.2) | 19.9 | 10.9–36.5 |
| ≥37 | 194 (65.5) | 565 (97.4) | 1.00 | Ref |
| Smoking in early pregnancy | ||||
| Non smokers | 240 (93.8) | 490 (90.4) | 1.00 | Ref |
| 1–9 cig/day | 12 (4.7) | 39 (7.2) | 0.63 | 0.32–1.22 |
| >9 cig/day | 4 (1.6) | 13 (2.4) | 0.63 | 0.20–1.95 |
| Missing | 40 | 38 | ||
| Gender (boys) | 153 (51.7) | 299 (51.6) | 1.01 | 0.76–1.33 |
| Diabetes (yes) | 6 (2.0) | 2 (0.3) | 5.98 | 1.20–29.8 |
| Gestational diabetes (yes) | 11 (3.7) | 11 (1.9) | 2.00 | 0.86–4.66 |
| Involuntary childlessness for at least one year (yes) | 25 (8.4) | 36 (6.2) | 0.82–2.37 | |
| Maternal country of origin Sweden | 191 (71.0) | 369 (65.8) | - | |
| Other Nordic countries Western Europe, USA | 10 (3.7) | 20 (3.6) | - | |
| Australia, New Zeeland | 3 (1.1) | 6 (1.1) | ||
| Former Eastern Europe | 24 (8.9) | |||
| Sub-Saharan Africa | 6 (2.2) | |||
| Middle East | 27 (10.0) | |||
| East Asia | 5 (1.9) | |||
| South America | 3 (1.1) | |||
| Missing | 27 | |||
a no estimates were calculated.