Table 1: Maternal demographic risk factors.

Maternal demographic risk factors
Non-acidaemia
pH > 7.20
(N = 294)
Acidaemia
pH < 7.20
(N = 294)
Missing %p-valueOdds ratios (95% CI)

Maternal age (years) mean ± SD29 [5.19]29 [5.82]0.664

Maternal AgeReference age231 (78.8%)229 (78.2%)0.3%REFERENCE
Teenage pregnancy6 (2.0%)6 (2.0%)0.9881.01 (0.32 - 3.17)
Advanced age I44 (15.0%)42 (14.3%)0.8720.96 (0.61 - 1.53)
Advanced age II12 (4.1%)16 (5.5%)0.4511.35 (0.62 - 2.91)

EthnicityWhite156 (65.3%)161 (68.5%)19.4%REFERENCE
Black20 (8.4%)17 (7.2%)0.580.82 (0.42 - 1.63)
Asian43 (18.0%)35 (14.9%)0.3500.79 (0.48 - 1.30)
Mixed8 (3.3%)6 (2.6%)0.5630.73 (0.25 - 2.14)
Other12 (5.0%)16 (6.8%)0.5201.29 (0.59 - 2.82)

BMI (kg/m2) mean ±SD25.3 [4.95]25.7 [5.7]0.496

BMI (kg/m2)Healthy weight126 (43.8%)122 (43.0%)2.7%REFERENCE
Underweight11 (3.8%)2 (0.7%)0.0320.19 (0.04 - 0.87)
Overweight83 (28.8%)88 (31.0%)0.6481.10 (0.74 - 1.62)
Obesity I39 (13.5%)49 (17.3%)0.2961.30 (0.80 - 2.12)
Obesity II23 (8.0%)11 (3.9%)0.0690.49 (0.23 - 1.06)
Obesity III6 (2.1%)12 (4.2%)0.1602.06 (0.75 - 5.68)

ParityNulliparity182 (63.2%)169 (59.5%)2.7%0.3650.86 (0.61 - 1.20)
Low multiparity100 (34.7%)111 (39.1%)2.7%0.2801.21 (0.86 - 1.70)
High multiparity6 (2.1%)4 (1.4%)2.7%0.7520.67 (0.19 - 2.41)

Demographic variables for acidaemia where the cutoff for acidaemia is pH = 7.20. Independent t-test was performed for maternal age and BMI and binary logistic regression was performed for all variables.