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Table 3 The relationship between risk factors and the four indicators of severe maternal morbidity

From: Comparison of global indicators for severe maternal morbidity among South Korean women who delivered from 2003 to 2018: a population-based retrospective cohort study

 

US-CDC’s SMM

P-value

Gold standard guideline for SMM

P-value

Zwart’s SMM

P-value

EURONET-SAMM

P-value

RR

95% CI

RR

95% CI

RR

95% CI

RR

95% CI

Individual factors

 Maternal age (y)

  15–19

1.35

1.25

1.45

 < .0001

1.27

1.19

1.36

 < .0001

0.85

0.64

1.13

0.277

1.05

0.95

1.17

0.3392

  20–24

1.09

1.06

1.12

 < .0001

1.09

1.06

1.11

 < .0001

0.88

0.81

0.95

0.0024

0.98

0.95

1.02

0.2914

  25–29

1.00

   

1.00

   

1.00

   

1.00

   

  30–34

1.10

1.08

1.11

 < .0001

1.05

1.04

1.07

 < .0001

1.17

1.12

1.21

 < .0001

1.14

1.12

1.16

 < .0001

  35–39

1.34

1.32

1.36

 < .0001

1.24

1.23

1.26

 < .0001

1.76

1.69

1.84

 < .0001

1.47

1.44

1.50

 < .0001

  40–44

1.67

1.63

1.71

 < .0001

1.52

1.49

1.56

 < .0001

2.72

2.55

2.90

 < .0001

2.04

1.97

2.11

 < .0001

  ≥ 45

1.85

1.67

2.04

 < .0001

1.70

1.54

1.87

 < .0001

3.19

2.56

3.97

 < .0001

2.49

2.17

2.86

 < .0001

 Household Income level

  1Q (Low)

1.17

1.15

1.19

 < .0001

1.14

1.12

1.16

 < .0001

1.30

1.24

1.36

 < .0001

1.13

1.10

1.15

 < .0001

  2Q

1.14

1.13

1.16

 < .0001

1.12

1.10

1.13

 < .0001

1.24

1.18

1.29

 < .0001

1.09

1.07

1.12

 < .0001

  3Q

1.07

1.06

1.09

 < .0001

1.06

1.05

1.08

 < .0001

1.11

1.07

1.16

 < .0001

1.04

1.02

1.06

 < .0001

  4Q (High)

1.00

   

1.00

   

1.00

   

1.00

   

 Type of health insurance

  Self-employed

1.14

1.13

1.16

 < .0001

1.12

1.11

1.13

 < .0001

1.21

1.17

1.25

 < .0001

1.14

1.12

1.15

 < .0001

  Employees

1.00

   

1.00

   

1.00

   

1.00

   

  Medical aid

1.80

1.71

1.89

 < .0001

1.70

1.63

1.78

 < .0001

1.58

1.37

1.81

 < .0001

1.57

1.46

1.68

 < .0001

 Residential areas

  Seoul

1.00

   

1.00

   

1.00

   

1.00

   

  Metropolitans

1.05

1.03

1.08

 < .0001

1.04

1.01

1.06

0.001

1.00

0.93

1.06

0.9168

1.05

1.02

1.08

0.0038

  Small cities

1.15

1.13

1.18

 < .0001

1.12

1.10

1.14

 < .0001

1.22

1.15

1.28

 < .0001

1.15

1.12

1.18

 < .0001

  Rural

1.21

1.18

1.24

 < .0001

1.17

1.14

1.20

 < .0001

1.49

1.39

1.60

 < .0001

1.39

1.34

1.44

 < .0001

Obstetric factors

 Mode of delivery

  Vaginal delivery

1.00

   

1.00

   

1.00

   

1.00

   

  Instrument delivery

1.53

1.51

1.56

 < .0001

1.38

1.36

1.40

 < .0001

1.37

1.30

1.43

 < .0001

1.49

1.46

1.52

 < .0001

  Cesarean section

2.28

2.25

2.32

 < .0001

1.84

1.82

1.86

 < .0001

2.51

2.41

2.61

 < .0001

1.41

1.39

1.44

 < .0001

 Preterm birth

  No

1.00

   

1.00

   

1.00

   

1.00

   

  Yes

1.39

1.36

1.42

 < .0001

1.36

1.34

1.39

 < .0001

1.61

1.53

1.70

 < .0001

1.53

1.49

1.58

 < .0001

 Parity

  0

1.25

1.24

1.27

 < .0001

1.27

1.26

1.28

 < .0001

1.15

1.12

1.19

 < .0001

1.39

1.37

1.41

 < .0001

  1 + 

1.00

   

1.00

   

1.00

   

1.00

   

 Multiple birth

  No

1.00

   

1.00

   

1.00

   

1.00

   

  Yes

1.64

1.60

1.67

 < .0001

1.59

1.56

1.62

 < .0001

1.37

1.29

1.46

 < .0001

1.37

1.32

1.42

 < .0001

 Prenatal care*

  Adequate

1.00

   

1.00

   

1.00

   

1.00

   

  Intermediate

1.13

1.12

1.15

 < .0001

1.05

1.04

1.06

 < .0001

1.10

1.06

1.14

 < .0001

0.97

0.95

0.99

0.0032

  Inadequate

1.39

1.33

1.45

 < .0001

1.26

1.21

1.31

 < .0001

1.38

1.23

1.54

 < .0001

1.10

1.03

1.17

0.0066

 Maternal comorbidities

  0

1.00

   

1.00

   

1.00

   

1.00

   

  ≥ 1

1.51

1.50

1.53

 < .0001

1.42

1.41

1.43

 < .0001

2.32

2.25

2.39

 < .0001

1.33

1.31

1.35

 < .0001

Provision factors

 Type of hospital

  ≥ 500 beds

5.54

5.45

5.62

 < .0001

4.47

4.40

4.53

 < .0001

3.29

3.15

3.44

 < .0001

2.53

2.48

2.59

 < .0001

  100–499 beds

2.94

2.89

2.99

 < .0001

2.54

2.50

2.57

 < .0001

2.61

2.50

2.71

 < .0001

1.35

1.32

1.38

 < .0001

  30–99 beds

1.00

   

1.00

   

1.00

   

1.00

   

  < 30 beds

1.04

1.03

1.06

 < .0001

1.04

1.03

1.06

 < .0001

0.69

0.66

0.72

 < .0001

0.81

0.80

0.83

 < .0001

 Region of hospital

  Seoul

1.00

   

1.00

   

1.00

   

1.00

   

  Metropolitan

1.35

1.32

1.38

 < .0001

1.32

1.30

1.35

 < .0001

1.60

1.51

1.69

 < .0001

1.52

1.47

1.57

 < .0001

  Small cities

1.23

1.21

1.25

 < .0001

1.22

1.20

1.24

 < .0001

1.02

0.97

1.07

0.4545

1.12

1.09

1.15

 < .0001

  Rural

1.17

1.10

1.24

< 0.0001

1.19

1.13

1.26

 < .0001

0.47

0.38

0.60

 < .0001

0.92

0.84

1.01

0.0704

  1. Adjusted for maternal age, household income level, type of health insurance, residential area, mode of delivery, preterm birth, parity, multiple birth, prenatal care, maternal comorbidities, type of hospital, region of hospital, and year
  2. EURONET-SAMM European Network on Severe Acute Maternal Morbidity, US-CDC United States Centers for Disease Control and Prevention, CI confidence interval, GSG gold standard guidelines, RR relative risk, SMM severe maternal morbidity
  3. *Prenatal care is estimated using Kessner’s adequate prenatal care index
  4. Maternal comorbidities included are: cardiac disease, renal disease, musculoskeletal disease, digestive disorder, blood disease, mental disorders, CNS disease, rheumatic heart disease, placentation disorder, chronic hypertension, pregnancy hypertension, lupus, collagen vascular disorder, rheumatoid arthritis, diabetes, diabetes complicating pregnancy, obesity, and asthma/chronic bronchitis