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Table 1 Descriptive statistics# for individual (Level-1) and DA (Level-2) covariates on term birth weight

From: Air pollution, neighbourhood and maternal-level factors modify the effect of smoking on birth weight: a multilevel analysis in British Columbia, Canada

Variable

Mean (sd)

Min-max

Level-1 (individual)

Maternal age

29.8 (5.60)

11 – 55

Nulliparous

0.45 (0.50)

0 – 1

Drug/Alcohol flag

0.02 (0.15)

0 – 1

Cigarettes/day

0.79 (2.91)

0 – 20

Fall/Winter season

0.48 (0.50)

0 – 1

Level-2 (DA) Variables

SESi

-0.08 (0.58)

-2.22 – 1.18

Education

0.50 (0.12)

0 – 0.95

Immigrant density

0.16 (0.19)

0 – 0.86

PM2.5

7.30 (0.86)

4.41 – 10.23

Rural address

0.11 (0.32)

0 – 1

  1. # values shown are unstandardized, non-centered; Nulliparous: patient has never delivered a baby of at least 500 g birth weight or at least 20 weeks gestation in a previous pregnancy; Drug or Alcohol Flag: physician indicated use of drugs (prescription, non-prescription, illicit) or alcohol as risk factor in pregnancy; Cigarettes/day: number of cigarettes smoked daily at 1st prenatal visit (self-reported); Fall/Winter Season: month or birth between September to February; SESi: socioeconomic status index; Education: proportion of population over 15 with any post-secondary education (trade, college, university); Immigrant Density: proportion of the population identified as immigrant status from continental Asia; PM2.5: Particulate Matter less than 2.5 μm; Rural: those having a rural residential address