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Table 4 Univariate analyses of possible confounding variables influencing birth weight, in full-term infants (n = 1124)

From: Smoking during pregnancy and harm reduction in birth weight: a cross-sectional study

Variable

β

SE

p

CI (β; 95%)

Age at delivery (years)b

−9.9

4.2

0.018

(−18.1 to −1.7)

  ≤ 8 years of education

35.04

47.94

0.465

(−58.92 to 128.99)

 9 to 11 years of education

8.63

44.3

0.846

(−78.35 to 95.62)

 Employed

24.5

45.6

0.592

(−65.2 to 114.2)

Live with a partnerb

91.9

69.2

0.185

(−44.1 to 227.9)

First pregnancyb

9.1

6.0

0.132

(−2.7 to 21.0)

Interval between deliveries (years)b

149.8

42.9

0.001

(65.5 to 234.0)

 Pregestational obesity or overweight

−55.7

478.5

0.907

(− 995.8 to 884.4)

Prenatal care in public serviceb

77.7

40.6

0.056

(−2.0 to 157.3)

≥ 7 prenatal medical visitsb

108.4

44.7

0.016

(20.7 to 196.1)

 Alcohol consumption

4.8

73.6

0.948

(− 139.6 to 149.2)

Illegal drug useb

− 247.6

170.7

0.147

(− 582.6 to 87.3)

 Participation in prenatal group

−31.9

35.6

0.371

(− 101.8 to 38.0)

 Advised regarding warning signs

−13.6

31.2

0.662

(−74.9 to 47.6)

 Use of folic acid and iron sulfate

11.5

39.2

0.770

(−65.4 to 88.3)

Emotional problemsb

81.9

54.1

0.130

(−24.3 to 188.2)

Anemiab

− 145.2

109.9

0.187

(−361.2 to 70.8)

High blood pressure/pre-eclampsia/eclampsia/ HELLP syndromea, b

− 175.5

114.5

0.126

(−400.5 to 49.6)

 Diabetes

−132.3

121.2

0.275

(− 370.5 to 105.8)

Hyperemesisb

− 229.8

120.0

0.056

(−465.7 to 6.1)

 Hemorrhage/bleeding/ threatened abortion

−105.6

113.3

0.352

(− 328.2 to 117.0)

Infectionb

− 165.9

100.4

0.099

(− 363.1 to 31.4)

  1. aHELLP hemolysis, elevated liver enzymes, low platelet count
  2. bSelected as potential confounder