Table 1 Maternal characteristics and the prevalence of the pre-pregnancy BMI groups.

From: Effects of pre-pregnancy body mass index on pregnancy and perinatal outcomes in women based on a retrospective cohort

Characteristics

BMI < 18.5 kg/m2 (n = 54,238)

18.5 kg/m2 ≤ BMI < 24.0 kg/m2(n = 282,480)

24.0 kg/m2 ≤ BMI < 28.0 kg/m2 (n = 51,251)

BMI ≥ 28.0 kg/m2 (n = 10,399)

Total

%

X2

P

n

%

Prevalence (%)

n

%

n

%

Prevalence (%)

n

%

Prevalence (%)

n

Maternal age

 < 20

16

0.03

12.6

92

0.03

16

0.03

12.6

3

0.03

2.36

127

0.03

  

20 ~ 

18,664

34.41

17.98

72,498

25.66

10,410

20.31

10.03

2234

21.48

2.15

103,806

26.06

  

25 ~ 

26,544

48.94

14.37

132,100

46.76

21,807

42.55

11.81

4225

40.63

2.29

184,676

46.36

7926.581

 < 0.001

30 ~ 

7434

13.71

9.4

56,532

20.01

12,520

24.43

15.84

2572

24.73

3.25

79,058

19.85

  

35 ~ 

1537

2.83

5.09

20,896

7.4

6437

12.56

21.3

1353

13.01

4.48

30,223

7.59

  

Missing

43

  

362

0.13

61

0.12

 

12

0.12

 

478

0.12

  

Ethnic groups

Han Chinese

49,115

90.55

13.89

251,571

89.06

44,242

86.32

12.51

8773

84.36

2.48

353,701

88.79

707.768

 < 0.001

Minority

5123

9.45

11.47

30,909

10.94

7009

13.68

15.69

1626

15.64

3.64

44,667

11.21

  

Education

Primary School or Below

619

1.14

10.07

4233

1.5

986

1.92

16.05

306

2.94

4.98

6144

1.54

  

Junior high school

14,472

26.68

12.25

82,662

29.26

17,218

33.6

14.58

3770

36.25

3.19

118,122

29.65

  

High School or Technical School

21,611

39.84

14.29

108,116

38.27

18,066

35.25

11.94

3470

33.37

2.29

151,263

37.97

3510.917

 < 0.001

College

12,854

23.7

16.09

57,187

20.24

8454

16.5

10.58

1395

13.41

1.75

79,890

20.05

  

Bachelor and above

1994

3.68

15.16

9720

3.44

1243

2.43

9.45

200

1.92

1.52

13,157

3.3

 

Missing

2688

4.96

 

20,562

7.28

5284

10.31

 

1258

12.1

 

29,792

7.48

  

Area of residence

Urban

3238

5.97

11.96

18,925

6.7

4084

7.97

15.08

828

7.96

3.06

27,075

6.8

196.147

 < 0.001

Rural

51,000

94.03

13.74

263,555

93.3

47,167

92.03

12.7

9571

92.04

2.58

371,293

93.2

  

Occupation

Farmer

33,633

62.01

13.66

175,194

62.02

31,026

60.54

12.6

6304

60.62

2.56

246,157

61.79

  

Worker

2076

3.83

14.36

10,112

3.58

1887

3.68

13.05

382

3.67

2.64

14,457

3.63

  

Merchant

1958

3.61

15.19

9055

3.21

1571

3.07

12.19

302

2.9

2.34

12,886

3.23

  

Teacher/public servant/office clerk

5010

9.24

16.09

22,569

7.99

3044

5.94

9.78

507

4.88

1.63

31,130

7.81

2842.649

 < 0.001

Housewife

2161

3.98

13.86

10,826

3.83

2116

4.13

13.57

490

4.71

3.14

15,593

3.91

  

Service personal

3769

6.95

13.96

19,735

6.99

2986

5.83

11.06

505

4.86

1.87

26,995

6.78

  

Others

2067

3.81

17.92

7840

2.78

1367

2.67

11.85

263

2.53

2.28

11,537

2.9

  

Missing

3564

6.57

 

27,149

9.61

7254

14.15

 

1646

15.83

 

39,613

9.94

  

Smoking

Yes

57

0.11

14.11

260

0.09

67

0.13

16.58

20

0.19

4.95

404

0.1

  

No

53,929

99.43

13.63

280,481

99.29

51,019

99.55

12.89

10,341

99.44

2.61

395,770

99.35

99.767

 < 0.001

Missing

252

0.46

 

1739

0.62

165

0.32

 

38

0.37

 

2194

0.55

  

Passive smoking

Yes

2183

4.02

16.12

9194

3.25

1834

3.58

13.55

327

3.14

2.42

13,538

3.4

88.192

 < 0.001

No

51,813

95.53

13.54

271,588

96.14

49,243

96.08

12.87

10,033

96.48

2.62

382,677

96.06

  

Missing

242

0.45

 

1698

0.6

174

0.34

 

39

0.38

 

2153

0.54

  

Alcohol consumption

Yes

383

0.71

14.42

1824

0.65

378

0.74

14.23

71

0.68

2.67

2656

0.67

  

No

53,594

98.81

13.62

278,907

98.74

50,690

98.91

12.88

10,292

98.97

2.62

393,483

98.77

8.15

0.078

Missing

261

0.48

 

1749

0.62

183

0.36

 

36

0.35

 

2229

0.56

  
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