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Table 5 Population attributable fractions for maternal systemic/localized comorbidity and preterm birth according to clinical subtype and gestational age*

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

 

Medically indicated

PPROM*

Spontaneous

 

< 28 wk

28-31 wk

32-36 wk

< 28 wk

28-31 wk

32-36 wk

< 28 wk

28-31 wk

32-36 wk

Systemic comorbidity

         

   Hypertension

         

Preeclampsia/eclampsia

21.6

38.0

21.9

-1.2

-0.7

-0.2

-1.2

-0.6

0.2

Pre-existing

0.8

1.1

1.6

0

0.1

0.1

0

0

-0.1

Gestational

0.2

1.8

1.8

-4.5

-0.8

-0.4

-2.4

-4.3

-0.3

   Cardiovascular disease

0.4

0.8

0.6

0.1

0.5

0.1

0.2

0.3

0.02

   Diabetes

         

Pre-existing

0.3

2.7

3.4

0.1

3.0

1.2

-0.1

1.4

0.5

Gestational

-1.9

0.6

2.6

-1.5

1.0

1.8

-3.0

-0.8

1.1

   Edema/renal disease

1.6

2.9

1.7

0.1

0.2

0.02

0.2

-0.03

0.03

   Genitourinary infection

1.7

3.7

1.9

1.7

3.6

0.5

0.7

-0.02

-0.05

   General infection

1.8

1.4

1.4

1.6

2.1

0.4

0.9

1.2

0.3

   Thyroid disease

1.4

1.0

0.9

0.6

0.8

0.3

0.1

0.5

0.1

   Anemia

11.9

14.8

5.9

6.7

6.6

-1.1

3.3

-0.1

-2.9

   Drug dependence

0.03

0.9

0.5

0.8

0.9

0.5

0.7

1.1

0.7

   Mental disorders

1.7

0.9

0.8

0.9

1.8

0.5

1.0

0.8

0.4

Localized comorbidity

         

   Hemorrhage

         

Placental abruption

23.5

21.0

9.8

14.1

17.9

2.4

25.2

22.9

4.5

Placenta previa

3.3

5.9

6.6

2.2

1.2

0.3

0.5

0.4

-0.1

   Chorioamnionitis

10.5

2.0

-0.3

31.4

30.7

3.8

25.1

11.7

0.04

   Amniotic sac

         

Polyhydramnios

1.3

2.3

1.5

0.3

0.8

0.2

0.7

1.8

0.4

Oligohydramnios

8.7

10.3

7.0

8.2

10.2

1.2

1.6

0.6

-0.2

   Cervical incompetence

7.2

1.4

0.7

8.1

3.5

0.5

14.6

3.1

0.6

   Structural abnormality

41.9

36.0

17.3

14.9

22.9

7.0

11.8

6.2

-1.2

   Previous cesarean delivery

1.4

2.3

8.7

0.4

-1.3

-2.3

-5.7

-4.7

-5.4

   Fetal anomaly

6.5

0.7

0.5

0.1

0.3

0.1

5.7

0.3

0.1

  1. * Preterm premature rupture of membranes
  2. † Spontaneous preterm labour before 37 gestational weeks with intact membranes