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Table 2 Incidence of infant mortality and adjusted incidence rates of the determinants analyzed according to birth weight strata

From: The relationship between the different low birth weight strata of newborns with infant mortality and the influence of the main health determinants in the extreme south of Brazil

 

Crude analysis

Adjusted analysis

Crude analysis

Adjusted analysis

Crude analysis

Adjusted analysis

Mortality rate (%)

P

IR (CI 95%) adj*

Mortality rate (%)

P

IR (CI 95%) adj*

Mortality rate (%)

P

IR (CI 95%) adj*

 

500–900 g

1000–1499 g

1500–2499 g

Biological determinants

Maternal age

 10–17 years

66.67

0.0153

0.93 (0.81;1.07)

19.67

0.0003

1.74 (1.15;2.65)

2.19

0.0106

1.40 (0.94;2.08)

 ≥ 35 years

42.37

0.0002

0.87 (0.74;1.02)

7.44

0.0512

0.78 (0.53;1.16)

1.48

0.8815

 

 18–34 years

56.79

 

1

10.79

 

1

1.44

 

1

Gender

 Male

59.85

0.0006

1.16 (1.05;1.27)

12.26

0.0563

1.29 (1.00;1.66)

1.72

0.0466

1.07 (0.85;1.35)

 Female

50.37

 

1

9.66

 

1

1.37

 

1

Gestational age

 < 22 weeks

92.50

< 0.0001

1.59 (1.29;1.96)

+

     

 22–27 weeks

63.19

< 0.0001

1.43 (1.23;1.66)

23.18

< 0.0001

1.90 (1.27;2.84)

+

  

 28–31 weeks

35.60

 

1

11.24

0.0099

1.27 (0.93;1.73)

5.03

< 0.0001

3.06 (2.03;4.61)

 32–36 weeks

+

  

7.48

 

1

1.62

0.0008

1.48 (1.13;1.94)

 ≥ 37 weeks

+

  

+

  

1.05

 

1

5-min Apgar Index

 < 7

75.68

< 0.0001

1.43 (1.29;1.59)

28.46

< 0.0001

2.90 (2.21;3.81)

11.36

< 0.0001

6.3 (4.61;8.71)

 ≥ 7

40.18

 

1

7.78

 

1

1.21

 

1

Skin color of the mother

 Black/Brown/Asian/Indigenous

62.86

0.0006

1.02 (0.92;1.14)

11.44

0.6284

 

1.82

0.0722

0.89 (0.68;1.18)

 White

52.49

 

1

10.67

  

1.45

 

1

Social determinants

Maternal schooling

 None/< 8 years

65.60

< 0.0001

1.11 (0.94;1.32)

15.07

0.0002

0.83 (0.55;1.25)

2.32

< 0.0001

1.65 (1.06;2.58)

 8–11 years

54.70

0.0001

1.01 (0.86;1.19)

9.08

0.3674

 

1.18

0.0598

1.12 (0.72;1.72)

 ≥ 12 years

39.73

 

1

7.64

 

1

0.83

 

1

Previous living children

 1

51.05

0.7130

 

11.49

0.0320

1.41 (1.00;1.98)

1.56

0.0620

1.26 (0.91;1.75)

 2

63.97

0.0060

1.13 (0.97;1.31)

15.94

< 0.0001

2.28 (1.55;3.35)

1.67

0.0560

1.20(0.79;1.80)

 ≥ 3

65.34

0.0001

1.07 (0.91;1.25)

15.00

< 0.0001

1.72 (1.13;2.63)

2.63

< 0.0001

1.43 (0.97;2.11)

 Nenhum

52.34

 

1

8.12

 

1

1.18

 

1

Previous deceased children

 ≥ 1

55.17

0.9570

 

7.80

0.0808

0.64 (0.40;1.03)

1.93

0.1333

1.19 (0.82;1.71)

 None

54.96

 

1

11.35

 

1

1.49

 

1

Health care determinants

Prenatal visits

 None

76.79

< 0.0001

1.03 (0.84;1.26)

16.86

< 0.0001

1.41 (0.84;2.37)

3.40

< 0.0001

2.38 (1.54;3.68)

 1–3

61.48

< 0.0001

1.00 (0.82;1.21)

14.79

< 0.0001

1.65 (1.05;2.60)

2.70

< 0.0001

2.14 (1.47;3.12)

 4–6

48.0

0.0012

0.92 (0.75;1.13)

10.95

0.0001

1.60 (1.02;2.49)

1.59

< 0.0001

1.49 (1.06;2.08)

 ≥ 7

34.55

 

1

4.82

 

1

0.85

 

1

Type of delivery

 Cesarean

37.93

< 0.0001

0.74 (0.66;0.84)

8.44

< 0.0001

0.75 (0.56;0.99)

1.46

0.4301

 

 Vaginal

72.34

 

1

16.02

 

1

1.60

  

Type of hospital

 Public

65.86

< 0.0001

1.85 (1.41;2.43)

12.05

0.0004

1.56 (0.84;2.88)

1.79

< 0.0001

1.01 (0.62;1.64)

 Mixed

47.66

< 0.0001

1.46 (1.10;1.94)

11.30

0.0015

1.45 (0.77;2.74)

1.57

0.0015

0.81 (0.49;1.33)

 Private

26.73

 

1

4.72

 

1

0.83

 

1

 

2500–2999 g

3000–3999 g

≥ 4000 g

Biological determinants

Maternal age

 10–17 years

0.58

0.4529

 

0.50

< 0.0001

1.56 (1.13;2.14)

0.30

0.9178

 

 ≥ 35 years

0.40

0.1821

0.72 (0.51;1.03)

0.16

0.0023

0.63 (0.45;0.88)

0.155

0.2458

 

 18–34 years

0.50

 

1

0.26

 

1

0.28

  

Gender

 Male

0.55

0.0886

1.11 (0.89;1.39)

0.30

0.0023

1.29 (1.07;1.57)

0.24

0.5527

 

 Female

0.45

 

1

0.23

 

1

0.29

  

Gestational age

 < 22 weeks

+

  

+

  

+

  

 22–27 weeks

+

  

+

  

+

  

 28–31 weeks

+

  

+

  

+

  

 32–36 weeks

0.77

0.0002

1.48 (1.11;1.99)

0.56

0.0005

1.55 (0.92;2.29)

+

  

 ≥ 37 weeks

0.45

 

1

0.26

 

1

0.26

  

5-min Apgar Index

 < 7

6.81

< 0.0001

12.19 (8.44;17.61)

6.06

< 0.0001

22.28 (17.9;29.06)

9.32

< 0.0001

58.54 (28.67;119.50)

 ≥ 7

0.44

 

1

0.22

 

1

0.17

 

1

Skin color of the mother

 Black/Brown/Asian/Indigenous

0.82

< 0.0001

1.30 (1.02;1.67)

0.43

< 0.0001

1.28 (1.05;1.57)

0.37

0.1162

1.53 (0.76;3.09)

 White

0.40

 

1

0.22

 

1

0.21

 

1

Social determinants

Maternal schooling

 None/< 8 years

0.91

< 0.0001

1.58 (1.00;2.47

0.47

< 0.0001

2.30 (1.53;3.46)

0.42

0.0278

2.24 (0.62;8.02)

 8–11 years

0.33

0.0378

0.88 (0.57;1.36)

0.24

< 0.0001

1.59 (1.07;2.35)

0.23

0.3293

1.39 (0.44;4.37)

 ≥ 12 years

0.22

 

1

0.10

 

1

0.14

 

1

Previous living children

 1

0.43

0.0340

1.35 (0.96;1.90)

0.24

0.3070

 

0.25

0.2870

 

 2

0.63

< 0.0001

1.63 (1.09;2.45)

0.31

0.0060

1.32 (0.96;1.81)

0.45

0.0240

2.69 (1.07;6.79)

 ≥ 3

1.30

< 0.0001

2.64 (1.82;3.81)

0.52

< 0.0001

1.65 (1.21;2.24)

0.34

0.1040

1.16 (0.41;3.31)

 Nenhum

0.31

 

1

0.21

 

1

0.15

  

Previous deceased children

 ≥ 1

0.59

0.2986

 

0.33

0.1362

1.16 (0.84;1.59)

0.22

0.7627

 

 None

0.49

  

0.26

 

1

0.26

  

Health care determinants

Prenatal visits

 None

1.81

< 0.0001

2.90 (2.01;4.19)

1.17

< 0.0001

3.79 (2.70;5.33)

1.82

< 0.0001

6.97 (2.24;21.70)

 1–3

1.03

< 0.0001

1.76 (1.26;2.45)

0.52

< 0.0001

1.81 (1.34;2.45)

0.54

0.0404

1.98 (0.61;6.44)

 4–6

0.56

< 0.0001

1.19 (0.88;1.59)

0.35

< 0.0001

1.36 (1.07;1.73)

0.22

0.7916

 

 ≥ 7

0.30

 

1

0.19

 

1

0.20

 

1

Type of delivery

 Cesarean

0.38

0.0004

0.96 (0.74;1.25)

0.24

0.0305

1.39 (1.13;1.70)

0.30

0.2895

 

 Vaginal

0.58

 

1

0.29

 

1

0.21

  

Type of Hospital

 Public

0.53

< 0.0001

1.30 (0.79;2.15)

0.31

< 0.0001

1.41 (0.93;2.13)

0.33

0.0932

1.16 (0.38;3.51)

 Mixed

0.73

< 0.0001

1.69 (1.02;2.79)

0.35

< 0.0001

1.60 (1.05;2.43)

0.21

0.4613

 

 Private

0.17

 

1

0.11

 

1

0.13

 

1

  1. *Adjusted model to variables of the same stratum with P < 0.20 in the bivariate analysis. IR, incidence ratio; CI 95%, confidence interval of 95% no population