Table 1 Characteristics of trial participants characteristics between balloon and control groups
Indicators | Balloon group | Control group | P | t/z/x2 |
|---|---|---|---|---|
n= 248 | n = 172 | |||
Maternal characteristics | ||||
 Maternal age (years) | 32.5 ± 5.1 | 32.7 ± 4.7 | 0.654 | 0.448 |
 BMI (kg/m2) | 21.7 ± 2.7 | 21.2 ± 2.5 | 0.081 | −1.744 |
 Gravidity (n) | 4 (2–13) | 4 (2–10) | 0.539 | −0.615 |
 Parity (n) | 1 (1–5) | 1 (1–3) | 0.123 | −1.543 |
 Number of previous CSs (n) | 1 (1–3) | 1 (1–3) | 0.332 | −0.971 |
 Number of previous abortions (n) | 2 (0–7) | 2 (0–8) | 0.531 | −0.626 |
 Gestational age at delivery (weeks) | 36+ 3 (28+ 3–40+ 4) | 36+ 2 (28+ 1–39+ 3) | 0.137 | −1.487 |
Neonatal characteristics | ||||
 Birthweight of the newborn (g) | 2778.3 ± 410.6 | 2592.7 ± 477.4 | 0.000 | −4.041 |
 1 min Apgar score | 9.1 ± 1.6 | 9.0 ± 1.8 | 0.696 | −0.399 |
 Neonatal ICU admission (n%) | 50/248 (20.16%) | 55/172 (31.98%) | 0.006 | 7.562 |
 Neonatal asphyxia (n%) | 34/248 (13.71%) | 26/172 (15.12%) | 0.685 | 0.164 |
 Neonatal death (n%) | 2/248 (0.81%) | 4/172 (2.33%) | 0.197 | 1.664 |
Ultrasound indicators | ||||
 Cervical canal length | 2.89 ± 0.09 | 3.06 ± 0.05 | 0.116 | 1.578 |
 Thickness of the placenta above the cervix | 3.91 ± 0.20 | 3.55 ± 0.15 | 0.139 | −1.468 |
 Thickness of the placenta in the lower uterine segment | 3.41 ± 0.13 | 3.35 ± 0.11 | 0.664 | - 0.435 |
 Anterior placenta | 224 (90.3%) | 151 (87.8%) | 0.409 | 0.681 |
 Myometrial thinning | 169 (68.1%) | 112 (65.1%) | 0.421 | 0.517 |
 Multiple placental sinusoids | 206 (83.1%) | 134 (77.9%) | 0.186 | 1.752 |
 Dilation of the cervical canal | 71 (28.6%) | 40 (23.3%) | 0.219 | 1.508 |
 Loss of retroplacental clear zone | 204 (82.3%) | 132 (76.7%) | 0.165 | 1.930 |
 Abnormal blood flow in retroplacental space | 235 (94.8%) | 158 (91.9%) | 0.234 | 1.418 |
 Bladder wall interruption | 42 (16.9%) | 23 (13.3%) | 0.321 | 0.986 |