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Table 2 Incidence of fore-lying or prolapse of the umbilical cord associated with the use of balloons for cervical ripening during labor among the singleton vertex cases

From: The use of balloons for uterine cervical ripening is associated with an increased risk of umbilical cord prolapse: population based questionnaire survey in Japan

  Incidence Odds ratio (95% confidence interval)
Controls (without balloon) 0.005% (88/1891189) Reference
When all cases regardless of the timing of the use of a balloon are calculated
Total Cases 0.064% (93/146271) 13.67 (10.21, 18.30)
  Intra-cervix balloon 0.018% (10/56065) 3.83 (1.99, 7.37)
  Disk shape balloon 0.060% (23/38348) 12.90 (8.15, 20.41)
  Ball type balloon 0.120% (56/46640) 25.83 (18.48, 36.12)
  Others 0.077% (4/5218) 16.49 (6.05, 44.92)
When only cases directly associated with the use of a balloon are calculated (during use and at the time of removal)
Total cases 0.030% (44/146271) 6.47 (4.50, 9.29)
  Intra-cervix balloon 0.004% (2/56065) 0.77 (0.19, 3.11)
  Disk shape balloon 0.060% (14/38348) 7.85 (4.46, 13.80)
  Ball type balloon 0.037% (28/46640) 12.91 (8.44, 19.75)
  Others 0% (0/5218) n/a
  1. The incidence observed in the control group was calculated based on the total number of deliveries.