Skip to main content

Table 3 Cox regression showing the hazard ratio (HR) of caesarean delivery comparing the defined BMI groups, with and without adjustment for covariates

From: Maternal obesity and its effect on labour duration in nulliparous women: a retrospective observational cohort study

  Total labour a
Covariates Crude HR 95% CI Adjusted HR 95% CI
BMI
 < 25 1   1  
 25–29.9 1.39 [1.06–1.81] 1.28 [0.97–1.69]
 ≥ 30 1.94 [1.40–2.69] 1.80 [1.28–2.54]
Height
 < 160 cm 1   1  
 160–169 cm 0.83 [0.60–1.15] 0.77 [0.55–1.09]
 170–179 cm 0.74 [0.52–1.05] 0.64 [0.44–0.93]
 ≥ 180 cm 0.67 [0.31–1.41] 0.50 [0.23–1.08]
Age
 < 25 1   1  
 25–29 0.99 [0.72–1.37] 0.97 [0.69–1.37]
 30–34 1.22 [0.88–1.68] 1.31 [0.94–1.84]
 ≥ 35 1.57 [1.08–2.29] 1.82 [1.22–2.69]
Birthweight
 < 3.0 kg 1   1  
 3.0–3.5 kg 0.89 [0.56–1.41] 0.98 [0.59–1.61]
 3.5–4.0 kg 1.03 [0.67–1.59] 1.13 [0.71–1.82]
 > 4.0 kg 1.39 [0.87–2.18] 1.43 [0.87–2.36]
Epidural
 No 1   1  
 Yes 1.16 [0.88–1.53] 0.96 [0.72–1.29]
Augmentation with oxytocin
 No 1   1  
 Yes 1.21 [0.85–1.72] 0.96 [0.65–1.42]
Induced labour
 No 1   1  
 Yes 1.80 [1.43–2.27] 1.67 [1.33–2.17]
Phase 1
  Crude HR 95% CI Adjusted HR 95% CI
BMI
 < 25 1   1  
 25–29.9 1.68 [1.07–2.66] 1.55 [0.97–2.48]
 ≥ 30 1.56 [0.86–2.84] 1.56 [0.84–2.89]
Phase 2
  Crude HR 95% CI Adjusted HR 95% CI
BMI
 < 25 1   1  
 25–29.9 1.22 [0.77–1.94] 1.08 [0.67–1.74]
 ≥ 30 1.56 [0.86–2.84] 1.56 [0.84–2.89]
  1. Phase 1 defined as the period of time from active labour until fully dilated
  2. Phase 2 defined as the period of time from when fully dilated until actual birth. Vaginal deliveries censored
  3. A HR > 1 illustrates an increased number of caesarean deliveries over time compared to the reference group; A shorter duration of labour. A HR < 1 illustrates a decreased number of vaginal deliveries over time compared to the reference group; A longer duration of labour
  4. a77 women (4.1%) did not have duration measures recorded and were therefore not accounted for in analysis