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Table 1 Characteristics of women by preterm birth (< 37 weeks gestational age)

From: Fertility treatments and the risk of preterm birth among women with subfertility: a linked-data retrospective cohort study

 

Term (> 37 weeks)

Preterm (< 37)

Total

P value

N

Row%

N

Row%

N

Col%

Maternal age at delivery

       

 ≤ 30

290

81.7%

65

18.3%

355

72.4%

0.669

 31+

108

80.0%

27

20.0%

135

27.6%

 

Paternal age at delivery

       

 ≤ 30

239

83.0%

49

17.0%

288

58.9%

0.223

 31+

158

78.6%

43

21.4%

201

41.1%

 

BMI category (pre-pregnancy)

       

 Underweight/Normal

184

76.0%

58

24.0%

242

55.1%

0.148

 Overweight/Obese

161

81.7%

36

18.3%

197

4.9%

 

Income (at interview)

       

 Less than $50,000

110

81.5%

25

18.5%

135

28.7%

0.938

 50,000–$99,999

213

80.1%

53

19.9%

266

56.6%

 

 Over $100,000

56

81.2%

13

18.8%

69

14.7%

 

Education level (at interview)

       

 Less than college grad

127

77.4%

37

22.6%

164

33.6%

0.136

 College grad or more

269

83.0%

55

17.0%

324

66.4%

 

Race/Ethnicity

       

 White, non-Hispanic

381

80.9%

90

19.1%

471

96.1%

0.348

 Hispanic, other non-White

17

89.5%

2

10.5%

19

3.9%

 

Religion

       

 Non-LDS

84

78.5%

23

21.5%

107

21.8%

0.415

 Latter-day Saint

314

82.0%

69

18.0%

383

78.2%

 

Attempt duration to conception

       

 < 12 months

69

81.2%

16

18.8%

85

17.4%

0.771

 12 to < 24

100

81.3%

23

18.7%

123

25.2%

 

 24 to < 36

73

85.9%

12

14.1%

85

17.4%

 

 36 to < 48

58

79.5%

15

20.5%

73

14.9%

 

 48+

97

78.9%

26

21.1%

123

25.2%

 

Recruitment cohort

       

 Clinic

203

76.3%

63

23.7%

266

54.3%

0.002

 Population

195

87.1%

29

12.9%

224

45.7%

 

Baby sex

       

 F

188

79.0%

50

21.0%

238

48.6%

0.219

 M

210

83.3%

42

16.7%

252

51.4%

 

Multiplicity

       

 Singleton

374

90.8%

38

9.2%

412

84.1%

0.000

 Twins

24

33.8%

47

66.2%

71

14.5%

 

 Triplets

0

0.0%

7

100.0%

7

1.4%

 

Treatment in cycle of conception

       

 None

190

89.2%

23

10.8%

214

43.5%

0.001

 Drugs

61

79.2%

16

20.8%

77

15.7%

 

 IUI

48

75.0%

16

25.0%

64

13.1%

 

 IVF

99

72.8%

37

27.2%

136

27.8%

 

Total

398

81.2%

92

18.8%

490

100.0%