Table 2 Associations of BMI with perinatal outcomes in Pakistani and White British women

From: A comparison of South Asian specific and established BMI thresholds for determining obesity prevalence in pregnancy and predicting pregnancy complications: findings from the Born in Bradford cohort

Outcome Pakistani women (N=4547) White British women (N=3931) P-interactiona
  Odds ratio (95% CI) per 5 kgm−2 P-linearb P-deviation from linearc Odds ratio (95% CI) per 5 kg m −2 P-linearb P-deviation from linearc  
Caesarean section 1.36 (1.27–1.45) <0.001 0.05 1.34 (1.26–1.42) <0.001 0.37 0.78
Hypertensive disorder of pregnancy 1.54 (1.39–1.71) <0.001 0.35 1.60 (1.46–1.76) <0.001 0.95 0.60
Macrosomia 1.57 (1.41–1.75) <0.001 0.48 1.36 (1.27–1.47) <0.001 0.89 0.04
Gestational diabetes 1.55 (1.43–1.69) <0.001 0.44 1.25 (1.12–1.40) <0.001 0.29 0.003
Pre-term birth 0.98 (0.87–1.11) 0.216 0.41 0.87 (0.77–0.98) 0.03 0.41 0.17
  1. Abbreviation: CI, confidence interval.
  2. Testing the null hypothesis that associations of BMI with outcome do not differ between Pakistani and White British women.
  3. bTesting the null hypothesis that there is no linear association across fifths of BMI (that is, P-value associated with linear increase across fifths).
  4. Testing the null hypothesis that the association of BMI with outcomes does not deviate from linearity (tested by comparing a model in which fifths for BMI are entered as four indicator variables with one in which the fifths of BMI distribution are entered as one ordinal (linear score) variable, using a likelihood ratio test to compare the two).