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Table 1 Descriptive Statistics of All Live Births and Preterm Births (PTB) in Shenzhen, China during 2003–2012

From: Temporal trends of preterm birth in Shenzhen, China: a retrospective study

 

Live births

Term births

Spontaneous preterm births b

Medically induced preterm birth

PROM-PTB

S-PTB

N

%

N

%

N

%

N

%

All live birth

1,385,882

1,307,570

94.35

7436

0.54

40,104

2.89

30,712

2.21

Maternal age (years)

  ≤ 20

81,436

75,759

93.03

315

0.39

4375

5.37

987

1.21

 21-35

1,230,521

1,164,107

94.60

6477

0.53

33,773

2.74

26,164

2.13

  ≥ 36

73,865

67,704

91.66

644

0.87

1956

2.65

3561

4.82

Maternal education

 Less than high school

599,640

565,404

94.29

2397

0.40

21,037

3.51

10,802

1.80

 High school and college

498,618

469,616

94.18

2993

0.60

13,912

2.79

12,097

2.43

 Bachelor

263,880

250,133

94.79

1884

0.71

4765

1.81

7098

2.69

 Postgraduate

23,684

22,417

94.65

162

0.68

390

1.65

715

3.02

Parity

 0

857,543

808,052

94.23

5277

0.62

25,120

2.93

19,094

2.23

  ≥ 1

523,788

495,377

94.58

2139

0.41

14,778

2.82

11,494

2.19

 Missing data

4491

–

–

–

–

–

–

  

APNCU index a

 Inadequate

635,795

590,381

92.86

3711

0.58

27,182

4.28

14,521

2.28

 Intermediate

388,153

366,230

94.35

2427

0.63

9716

2.50

9780

2.52

 Appropriate

164,493

157,253

95.60

876

0.53

2458

1.49

3906

2.37

 Appropriate plus

197,234

193,572

98.14

421

0.21

744

0.38

2497

1.27

 Missing

147

–

–

–

–

–

–

  

Maternal chronic conditions

 Yes

3152

2629

83.41

80

2.54

102

3.24

341

10.82

 No

1,382,670

1,304,941

94.38

7356

0.53

40,002

2.89

30,371

2.20

Gestational hypertension

 Yes

5008

4496

89.78

72

1.44

101

2.02

339

6.77

 No

1,380,814

1,303,074

94.37

7364

0.53

40,003

2.90

30,373

2.20

Preeclampsia or eclampsia

 Yes

16,208

12,644

78.01

102

0.63

309

1.91

3153

19.45

 No

1,369,614

1,294,926

94.55

7334

0.54

39,795

2.91

27,559

2.01

Infant sex

 Male

752,163

707,283

94.03

4306

0.57

23,432

3.11

17,142

2.28

 Female

633,466

600,123

94.74

3130

0.49

16,648

2.63

13,565

2.14

 Hermaphrodite

193

164

84.97

0.00

0.00

24

12.44

5

2.59

  1. aAPNCU the adequacy of prenatal care utilization
  2. bPROM-PTB preterm birth following premature rupture of membranesm, S-PTB preterm birth due to spontaneous preterm labor