Table 6 Smoking cohort, gestation (Days) 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 = 0.50)

Parsimonious model (R2a = 0.47)

β

95% CI

P Value

β

95% CI

P Value

β

95% CI

P Value

Days of PM2.5 Exposure (> 25 µg/m 3 )

0.01

-0.03, 0.04

0.708

0.01

-0.01, 0.04

0.353

0.01

-0.01, 0.04

0.309

Birthweight (g)

0.02

0.01, 0.02

< 0.001

0.02

0.016, 0.017

< 0.001

0.02

0.02, 0.02

< 0.001

Gender

Female

1.44

0.62, 2.26

0.001

3.12

2.54, 3.70

< 0.001

3.18

2.58, 3.78

< 0.001

Male

Ref

        

Diabetes

Yes

-4.86

-6.13, -3.58

< 0.001

-4.61

-5.55, -3.67

< 0.001

   

Unknown

0.22

-3.75, 4.19

0.914

0.40

-2.54, 3.34

0.791

   

No

Ref

        

Foetal Growth Restriction

Yes

-11.96

-13.53, -10.38

< 0.001

2.98

1.73, 4.24

< 0.001

   

Clinical Suspicion

-4.72

-6.52, -2.92

< 0.001

4.80

3.44, 6.15

< 0.001

   

Unknown

-6.87

-15.18, 1.43

0.105

3.75

-2.53, 10.04

0.242

   

No

Ref

        

Ethnicity

Non-Indigenous

1.26

0.31, 2.21

0.009

0.30

-0.41, 1.01

0.403

   

Unknown

1.07

-4.73, 6.87

0.717

-0.43

-4.60, 3.74

0.839

   

Indigenous

Ref

        

Previous Pregnancy

Yes

-2.95

-3.86, -2.04

< 0.001

-3.21

-3.93, -2.49

< 0.001

-3.06

-3.72, -2.40

< 0.001

No

Ref

        

Hypertension

Yes

-5.57

-7.55, -3.60

< 0.001

-2.67

-4.09, -1.24

< 0.001

   

Unknown

0.88

-6.88, 8.65

0.823

3.41

-2.23, 9.04

0.236

   

No

Ref

        

Anaemia

Yes

1.07

-0.03, 2.18

0.058

-0.26

-1.05, 0.53

0.520

   

Unknown

0.03

-0.90, 0.95

0.954

0.61

-0.09, 1.32

0.098

   

No

Ref

        

Birth Type

Instrumental Birth

2.83

1.19, 4.47

0.001

0.94

-0.26, 2.15

0.125

   

Caesarean Birth

-4.25

-5.16, 3.35

< 0.001

-2.10

-2.76, -1.43

< 0.001

   

Vaginal Birth

Ref

        

Maternal Age

 

-0.24

-0.31, -0.17

< 0.001

-0.01

-0.06, 0.04

0.732

   

Maternal BMI

 

0.09

0.03, 0.15

0.004

-0.08

-0.13, -0.04

< 0.001

-0.18

-0.22, -0.14

< 0.001

PM2.5 Tower Location

Beresfield

0.78

-1.69, 3.24

0.537

-1.99

-3.89, -0.09

0.040

   

Gunnedah

3.67

-0.03, 7.37

0.052

-0.72

-3.41, 1.98

0.602

   

Muswellbrook

2.91

-0.07, 5.89

0.056

-1.04

-3.27, 1.20

0.362

   

Narrabri

-2.19

-6.06, 1.68

0.267

-2.72

-5.56, 0.11

0.060

   

Singleton

3.95

1.00, 6.89

0.009

-0.30

-2.53, 1.92

0.790

   

Tamworth

1.06

-1.56, 3.69

0.426

-1.24

-3.22, 0.75

0.221

   

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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