Table 1.

Baseline maternal characteristics according to period of pregnancy for data used to evaluate performance of new national maternal early warning score

Characteristics	Early antenatal (<18 weeks' gestation, n=841)	Antenatal (18-40 weeks' gestation, n=998)	Postnatal (0-16 days after delivery, n=889)
Median (range) No of observations for each participant	1 (1-2)	4 (1-7)	10 (1-18)
Mean (SD) age (years)	31.6 (4.67)	31.6 (4.77)	31.7 (4.73)
Mean (SD) weight (kg)	68.1 (13.4)	68.3 (13.6)	67.9 (13.4)
Mean (SD) body mass index	24.9 (4.55)	24.9 (4.61)	24.8 (4.46)
Body mass index category
Normal weight (18.5-24.9)	489 (58.0)	585 (58.5)	534 (60.1)
Overweight (25.0-29.9)	236 (28.1)	271 (27.2)	233 (26.2)
Obese (≥30)	115 (13.7)	140 (14.0)	118 (13.3)
Nulliparous	366 (43.5)	447 (44.8)	401 (45.1)
Ethnic group
White	722 (85.9)	853 (85.5)	764 (85.9)
Asian	42 (5.0)	50 (5.0)	39 (4.4)
African or Caribbean	19 (2.3)	21 (2.1)	16 (1.8)
Mixed	16 (1.9)	17 (1.7)	16 (1.8)
Other	42 (5.0)	57 (5.7)	54 (6.1)
Site
Oxford	661 (78.6)	749 (75.1)	669 (75.3)
Newcastle	103 (12.2)	148 (14.8)	134 (15.1)
London	77 (9.2)	101 (10.1)	86 (9.7)
Smoker	60 (7.1)	69 (6.9)	54 (6.1)
Anaemia	6 (0.7)	7 (0.7)	6 (0.7)
Pregestational diabetes	6 (0.7)	6 (0.6)	6 (0.7)
Pre-existing hypertension†	11 (1.3)	16 (1.6)	14 (1.6)
Cardiac disease‡	12 (1.4)	12 (1.2)	11 (1.2)
Pre-existing renal disease	21 (2.5)	24 (2.4)	18 (2.0)

Data are number (%) unless indicated otherwise.

*Haemoglobin concentration <110 g/L.

†Not receiving drug treatments.

‡Non-ischaemic, non-congenital.

SD, standard deviation.