Table 1 Baseline characteristics of the study populations categorized by early pregnancy BMI tertiles

BMI tertile range

12.5, 20.6

20.7, 24.3

24.4, 39.2

15.4, 23.1

23.1, 27.0

27.1, 42.3

 Age (y)

26.5 (6.06)

29.1 (5.18)

30.2 (6.06)

< 0.0011

26.3 (4.5)

28.0 (5.3)

29.7 (5.0)

< 0.0011

 Height (cm)

156.7 (5.7)

155.8 (5.9)

155.4 (5.8)

0.151

161.4 (6.4)

161.3 (6.6)

160.5 (6.4)

0.141

 Weight (kg)

45.6 (4.5)

54.7 (5.0)

67.5 (8.6)

< 0.0011

53.8 (6.1)

64.7 (6.2)

79.1 (9.4)

< 0.0011

Education (%)

0.792

0.372

 low

25 (17.4)

22 (15.4)

25 (16.9)

88 (26.3)

83 (25.2)

69 (20.5)

 medium

94 (65.3)

90 (62.9)

89 (60.1)

214 (64.1)

206 (62.6)

223 (66.4)

 high

25 (17.4)

31 (21.7)

34 (23.0)

32 (9.6)

40 (12.2)

44 (13.1)

Employment (%)

0.022

0.262

 not working

67 (46.5)

66 (47.1)

87 (58.8)

47 (14.1)

50 (15.2)

35 (10.4)

 non-formal

8 (5.6)

13 (9.3)

17 (11.5)

245 (73.4)

237 (72.0)

265 (78.9)

 formal

69 (47.9)

61 (43.6)

44 (29.7)

42 (12.6)

42 (12.8)

36 (10.7)

Second hand smoking (%)

31 (57.4)

34 (66.7)

35 (56.5)

0.492

 Gestational age (wk)^a

9.1 (3.4)

8.7 (3.5)

9.4 (3.3)

0.143

12.2 (2.9)

12.3 (2.8)

11.7 (3.0)

0.113

Gravidity (%)

< 0.0012

< 0.0012

 primigravida

67 (57.8)

39 (34.5)

34 (27.0)

99 (29.6)

80 (24.3)

44 (13.1)

 multigravida

49 (42.2)

74 (65.5)

92 (73.0)

235 (70.4)

249 (75.7)

292 (86.9)

 Haemoglobin (g/dL)

12.0 (1.3)

12.4 (1.1)

12.6 (1.0)

< 0.0011

10.9 (1.8)

11.1 (1.4)

11.5 (1.5)

< 0.0011

 MCV below 80.0 fL (%)

42 (29.0)

27 (19.0)

29 (19.9)

0.082

Comorbidities^b

56 (16.8)

52 (15.8)

46 (13.7)

0.532

 Low birth weight (%)

7 (6.4)

5 (4.5)

5 (4.0)

0.682

22 (8.8)

20 (7.7)

16 (6.0)

0.492

 Prematurity (%)

5 (4.5)

5 (4.5)

7 (5.7)

0.892

18 (7.4)

22 (8.9)

20 (8.0)

0.832

 Stillbirth (%)

1 (0.9)

1 (0.9)

1 (0.8)

1.004

3 (1.2)

2 (0.8)

1 (0.4)

0.464