Table 3 Complete cohort, birthweight regression analysis.

From: Effects of PM2.5 exposure during high bushfire smoke days on birthweight and gestational age in Hunter New England, NSW, Australia. A study on pregnant people who smoke and don’t smoke

Variable

Level

Univariate

Full model (R2a = 0.52)

Parsimonious model (R2a = 0.52)

β

95% CI

P Value

β

95% CI

P Value

β

95% CI

P Value

Days of PM2.5 Exposure (> 25 µg/m 3 )

-0.44

1.01, 0.13

0.127

-0.42

-0.86, 0.03

0.065

-0.77

-1.19, − 0.36

< 0.001

Gestation (Days)

28.13

27.71, 28.54

< 0.001

26.59

26.19, 26.99

< 0.001

26.18

25.79, 26.57

< 0.001

Gender

Female

-115.85

-129.56, -102.15

< 0.001

-124.59

-134.11, -115.07

< 0.001

-125.62

-135.16, -116.08

< 0.001

Male

Ref

        

Smoking

Yes

-265.66

-283.67, -247.65

< 0.001

-141.73

-154.94, -128.52

< 0.001

-141.98

-155.02, -128.94

< 0.001

No

Ref

        

Diabetes

Yes

-89.29

-110.65, -67.92

< 0.001

48.86

33.38, 64.33

< 0.001

   

Unknown

-123.71

-232.36, -15.06

0.026

-42.08

-118.37, 34.21

0.280

   

No

Ref

        

Foetal Growth Restriction

Yes

-1072.41

-1108.07, -1036.74

< 0.001

-617.53

-645.03, -590.02

< 0.001

-620.45

-648.02, -592.87

< 0.001

Clinical Suspicion

-719.37

-761.69, -677.05

< 0.001

-490.91

-522.90, -458.92

< 0.001

-495.65

-527.72, -463.59

< 0.001

Unknown

-897.84

-1099.87, -695.81

< 0.001

-576.64

-729.88, -423.40

< 0.001

-613.61

-765.59, -461.64

< 0.001

No

Ref

        

Ethnicity

Non-Indigenous

76.15

54.39, 97.91

< 0.001

-4.81

-20.39, 10.76

0.545

   

Unknown

-27.95

-113.47, 57.57

0.522

-21.20

-81.63, 39.22

0.492

   

Indigenous

Ref

        

Previous Pregnancy

Yes

93.44

79.14, 107.74

< 0.001

132.44

121.60, 143.29

< 0.001

130.48

120.01, 140.96

< 0.001

No

Ref

        

Hypertension

Yes

-233.23

-262.25, -204.20

< 0.001

-40.48

-61.26, -19.71

< 0.001

   

Unknown

-443.15

-675.81, -210.49

< 0.001

-190.63

-353.78, -27.49

0.022

   

No

Ref

        

Anaemia

Yes

61.25

42.77, 79.72

< 0.001

36.49

23.65, 49.33

< 0.001

39.90

27.07, 52.72

< 0.001

Unknown

31.33

15.73, 46.92

< 0.001

-15.99

-27.57, -4.39

0.007

-16.67

-28.10, -5.25

0.004

No

Ref

        

Birth Type

Instrumental Birth

13.64

-11.14, 38.43

0.281

-11.66

-29.33, 6.02

0.196

   

Caesarean Birth

-54.28

-69.55, -39.02

< 0.001

50.54

39.62, 61.47

< 0.001

   

Vaginal Birth

Ref

        

Maternal Age

 

0.60

-0.66, 1.86

0.35

-2.50

-3.45, 1.56

< 0.001

-1.79

-2.72, -0.87

< 0.001

Maternal BMI

 

8.88

7.85, 9.90

< 0.001

8.88

8.13, 9.63

< 0.001

9.67

8.95, 10.39

< 0.001

PM2.5 Tower Location

Beresfield

105.33

64.37, 146.30

< 0.001

82.34

51.90, 112.79

< 0.001

   

Gunnedah

79.76

15.57, 143.95

0.015

33.43

-11.98, 78.84

0.149

   

Muswellbrook

126.90

73.52, 180.28

< 0.001

73.65

35.17, 112.13

< 0.001

   

Narrabri

79.91

9.67, 150.15

0.026

103.09

53.28, 152.89

< 0.001

   

Singleton

156.72

111.66, 207.79

< 0.001

84.62

49.56, 119.68

< 0.001

   

Tamworth

58.57

13.75, 103.38

0.010

66.53

33.63, 99.43

< 0.001

   

Armidale

Ref

        
  1. Key: ref: reference variable for which all other levels within the variable are assessed. “PM2.5 tower” denotes the suburb location of the air quality monitoring site from which the exposure variables were collected.
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