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Table 2 Preterm birth (PTB) rates according to maternal systemic/localized comorbidity and gestational age (weeks) at delivery, and the proportions of comorbidity among PTBs

From: Association between maternal comorbidity and preterm birth by severity and clinical subtype: retrospective cohort study

 

All PTB %

Medically indicated

%

PPROM*

%

Spontaneous†

%

Comorbidity‡ %

Total births

 

< 37

   < 28

28-31

32-36

< 37

   < 28

28-31

32-36

< 37

   < 28

28-31

32-36

< 37

< 37

 

Systemic comorbidity

               

   Hypertension

               

Preeclampsia/eclampsia

24.1

   1.0

3.3

16.3

20.6

   0

0.1

1.2

1.3

   0

0.1

2.1

2.2

8.7

29,915

Pre-existing

11.0

   0.2

0.7

5.8

6.7

   0.1

0.1

1.9

2.1

   0.1

0.1

1.9

2.1

0.8

7,439

Gestational

6.1

   0.1

0.2

3.2

3.5

   0

0.1

1.1

1.2

   0

0

1.3

1.4

1.0

11,380

   Cardiovascular disease

10.3

   0.2

0.6

4.4

5.3

   0.2

0.3

2.1

2.6

   0.2

0

2.2

2.5

0.6

4,434

   Diabetes

               

Pre-existing

13.1

   0.1

0.6

5.5

6.1

   0.1

0.5

3.1

3.7

   0.1

0.3

2.9

3.2

2.7

16,938

Gestational

8.4

   0.1

0.2

2.6

2.8

   0.1

0.2

2.4

2.7

   0

0.1

2.8

2.9

5.1

50,313

   Edema/renal disease

17.0

   0.6

1.9

9.9

12.4

   0.1

0.2

1.6

2.0

   0.3

0.1

2.3

2.6

0.8

3,977

   Genitourinary infection

8.4

   0.2

0.5

2.7

3.3

   0.2

0.4

2.0

2.6

   0.2

0.1

2.1

2.5

3.2

31,477

   General infection

10.0

   0.2

0.4

3.2

3.8

   0.3

0.4

2.2

2.9

   0.3

0.2

2.7

3.2

1.9

16,024

   Thyroid disease

8.9

   0.2

0.4

3.0

3.7

   0.2

0.3

2.3

2.8

   0.2

0.2

2.2

2.5

1.4

12,687

   Anemia

6.9

   0.2

0.4

2.3

2.9

   0.2

0.2

1.5

2.0

   0.2

0.1

1.7

2.0

11.7

140,410

   Drug dependence

21.4

   0.2

0.8

4.5

5.5

   0.6

0.7

5.0

6.2

   0.6

0.7

8.5

9.8

3.9

3,229

   Mental disorders

13.2

   0.4

0.5

3.7

4.5

   0.3

0.6

3.2

4.1

   0.4

0.3

3.9

4.6

9.3

7,688

Localized comorbidity

               

   Hemorrhage

               

Placental abruption

31.9

   1.3

2.4

9.9

13.6

   1.3

1.6

3.6

6.6

   2.3

1.8

7.6

11.7

8.6

22,278

Placenta previa

35.2

   0.8

2.9

26.3

30.0

   0.9

0.5

2.4

3.8

   0.3

0.2

1.1

1.5

2.3

5,265

   Chorioamnionitis

11.0

   0.3

0.3

1.4

1.9

   1.2

1.2

3.1

5.5

   1.0

0.5

2.1

3.6

7.3

55,133

   Amniotic sac

               

Polyhydramnios

12.5

   0.3

0.8

4.9

6.0

   0.2

0.3

2.0

2.5

   0.3

0.5

3.4

4.1

1.3

8,861

Oligohydramnios

20.6

   0.8

1.8

10.4

13.0

   1.1

1.4

3.2

5.7

   0.3

0.2

1.5

1.9

3.8

15,293

   Cervical incompetence

47.4

   3.4

1.5

6.4

11.2

   6.3

2.7

5.7

14.7

   11.3

2.1

8.1

21.5

1.5

2,570

   Structural abnormality

13.0

   0.6

1.1

5.1

6.7

   0.4

0.6

3.2

4.2

   0.4

0.2

1.5

2.1

3.1

19,515

   Previous cesarean delivery

5.8

   0.1

0.2

2.9

3.3

   0.1

0.1

1.3

1.5

   0.1

0.1

0.9

1.0

8.4

118,608

   Fetal anomaly

43.2

   8.2

1.9

11.7

21.9

   0.2

0.6

2.4

3.2

   12

0.6

5.5

18.1

0.5

935

Total

6.2

   0.1

0.2

1.5

1.8

   0.1

0.1

1.7

1.9

   0.1

0.1

2.2

2.5

 

1,329,737

  1. * Preterm premature rupture of membranes
  2. † Spontaneous preterm labour before 37 weeks of gestation with intact membranes
  3. ‡ Proportion of comorbidity among PTBs overall
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