Table 1.
Cohort characteristics (n = 154).
| sPTB (n = 26) |
no sPTB (n = 128) |
Missing |
||||
|---|---|---|---|---|---|---|
| n | % | n | % | n | % | |
| Gestational age at inclusion (mean, sd) | 12.5 | 1.6 | 13.0 | 2.1 | ||
| Age (mean, SD) | 32.7 | 3.9 | 32.4 | 4.5 | ||
| Ethnicity | 4 | 2.6 | ||||
| White European | 14 | 53.8 | 55 | 44.4 | ||
| African | 3 | 11.5 | 26 | 21.0 | ||
| Surinamese | 1 | 3.8 | 13 | 10.5 | ||
| Turkish | 2 | 7.7 | 4 | 3.2 | ||
| Indian | 0 | 5 | 4.0 | |||
| Other Asian | 3 | 11.5 | 2 | 1.6 | ||
| Hispanic | 1 | 3.8 | 4 | 3.2 | ||
| Mixed | 2 | 7.7 | 12 | 9.7 | ||
| Other | 0 | 3 | 2.4 | |||
| Smoking during entire pregnancy | 0 | 3 | 2.3 | |||
| BMI (median, IQR) | 24.8 | 20.5–28.8 | 24.2 | 21.8–28.6 | 3 | 1.9 |
| Previous sexually transmitted infections | ||||||
| Chlamydia trachomatis | 4 | 15.4 | 14 | 10.9 | ||
| Neisseria gonorrhoeae | 2 | 7.7 | 1 | 0.8 | ||
| Parity | ||||||
| 1 | 17 | 65.4 | 65 | 50.8 | ||
| 2 | 3 | 11.5 | 34 | 26.6 | ||
| ≥3 | 6 | 23.0 | 29 | 22.6 | ||
| Previous preterm delivery | ||||||
| <23 + 0 weeks of gestation | 5 | 19.2 | 45 | 35.2 | ||
| <28+0weeks of gestation | 10 | 38.5 | 39 | 30.5 | ||
| Interpregnancy interval in months | ||||||
| <6 months | 8 | 30.8 | 28 | 21.9 | ||
| 6–12 months | 4 | 15.4 | 25 | 19.5 | ||
| >12 months | 14 | 53.8 | 75 | 58.6 | ||
| ART current pregnancy | ||||||
| IUI | 0 | 1 | 0.8 | |||
| IVF | 3 | 11.5 | 3 | 2.3 | ||
| ICSI | 1 | 3.8 | 9 | 7.0 | ||
| Bacterial vaginosis screening | ||||||
| receiving treatment | 7 | 26.9 | 40 | 31.3 | ||
| vaginal complaints during first trimester | 1 | 3.8 | 4 | 3.1 | ||
| Preventive therapies | ||||||
| Progesterone | 24 | 92.3 | 117 | 93.6 | 3* | 1.9 |
| Cervical cerclage placed transvaginally during pregnancy | 5 | 19.2 | 26 | 20.3 | 4* | 2.6 |
| Cervical cerclage placed transabdominally pre-pregnancy | 0 | 3 | 2.3 | 4* | 2.6 | |
| Cervical pessary | 3 | 11.5 | 5 | 3.9 | ||
| Cervical length < 25 mm | 7 | 26.9 | 18 | 14.1 | 18** | 11.7 |
| Twin pregnancy | 3 | 11.5 | 2 | 1.6 | 6* | 3.8 |
| Timing of delivery | 1 | 0.6 | ||||
| Spontaneous miscarriage <16+0 weeks | 0 | 2 | 1.6 | |||
| Termination for congenital anomalies | 0 | 3 | 2.3 | |||
| Late miscarriage (16–22+6 weeks of gestation) | 2 | 7.7 | 0 | |||
| Spontaneous preterm birth (23+0–36+6 weeks of gestation) | 24 | 92.3 | 0 | |||
| medically indicated preterm birth 23+0–36+6 weeks of gestation) | 0 | 8 | 6.3 | |||
| Term birth (>37+0 weeks of gestation) | 0 | 114 | 89.8 | |||
SD: standard deviation. IQR: interquartile range. *including miscarriages <16 + 0 weeks of gestation and pregnancy terminations. **including miscarriages <16 + 0 weeks of gestation and pregnancy terminations and participants with cervical cerclage or pessary in situ before start routine cervical length measurements.