Table 1.
Baseline characteristics of participants
| Intervention (n = 2269) | Control (n = 2033) | |||
|---|---|---|---|---|
| Maternal characteristics | ||||
| Age category (years) | N | % | N | % |
| < 20 | 16 | 0.71 | 17 | 0.89 |
| 20–35 | 1685 | 74.33 | 1431 | 71.08 |
| > 35 | 566 | 24.97 | 565 | 28.10 |
| Missing | 2 | 0.09 | 20 | 0.98 |
| Ethnic origin | ||||
| Western | 2020 | 89.70 | 1736 | 85.77 |
| Non-western | 232 | 10.30 | 288 | 14.24 |
| Missing | 17 | 0.75 | 9 | 0.44 |
| Smoking during pregnancy | ||||
| No | 1230 | 81.35 | 1294 | 87.79 |
| Yes | 282 | 18.65 | 182 | 8.99 |
| Missing | 757 | 33.36 | 557 | 27.40 |
| Single mother | ||||
| No | 1967 | 95.35 | 1439 | 87.14 |
| Yes | 96 | 4.65 | 46 | 3.10 |
| Missing | 206 | 9.08 | 548 | 26.98 |
| Family income net (euros/month) | ||||
| < 1000 | 116 | 7.89 | 106 | 7.37 |
| 1000–1499 | 233 | 15.85 | 176 | 12.23 |
| 1500–1999 | 203 | 13.81 | 160 | 11.12 |
| 2000–2499 | 228 | 15.51 | 195 | 13.55 |
| 2500–2999 | 239 | 16.26 | 204 | 14.18 |
| > 3000 | 451 | 30.68 | 598 | 41.56 |
| Missing | 799 | 35.21 | 594 | 29.22 |
| Educational level | ||||
| Low | 199 | 13.17 | 179 | 12.30 |
| Medium | 672 | 44.47 | 463 | 31.80 |
| High | 640 | 42.36 | 814 | 55.91 |
| Missing | 758 | 33.41 | 577 | 28.38 |
| Socioeconomic status | ||||
| Low (< P20) | 1485 | 72.79 | 862 | 46.59 |
| Medium (P20–P80) | 457 | 22.40 | 731 | 39.51 |
| High (> P80) | 98 | 4.80 | 257 | 13.89 |
| Missing | 229 | 10.09 | 183 | 9.00 |
| BMI at start pregnancy | ||||
| BMI < 25 | 1021 | 45.20 | 1098 | 54.30 |
| BMI 25–35 | 943 | 41.74 | 736 | 36.40 |
| BMI > 35 | 295 | 13.06 | 188 | 9.30 |
| Missing | 10 | 0.44 | 11 | 0.54 |
| Prior pregnancy characteristics | ||||
| Previous SGA baby | ||||
| Nulliparous | 1079 | 47.55 | 985 | 48.50 |
| No | 700 | 36.12 | 860 | 92.18 |
| Yes | 159 | 8.20 | 73 | 7.82 |
| Missing | 331 | 14.59 | 115 | 10.97 |
| Previous preterm delivery | ||||
| Nulliparous | 1079 | 47.55 | 985 | 48.50 |
| No | 824 | 41.78 | 883 | 93.94 |
| Yes | 69 | 3.50 | 57 | 6.06 |
| Missing | 297 | 13.09 | 108 | 10.31 |
| Pregnancy characteristics | ||||
| Parity | ||||
| Nulliparous | 1079 | 47.55 | 985 | 48.50 |
| Multiparous | 1190 | 52.45 | 1048 | 51.60 |
| Missing | 0 | 0 | 0 | 0 |
Values are expressed as numbers (first) and percentage (second). Percentages of categorised values are percentages of non-missing cases. Missing percentages are percentages of total cases