Skip to main content

Table 1 Characteristics of eligible cohort members assigned exposures and those who were not assigned exposures.

From: The association between low level exposures to ambient air pollution and term low birth weight: a retrospective cohort study

Covariate   Subjects assigned exposure data N = 74,284 Subjects with no exposure data N = 14,849
Maternal age: Mean (SD)   28.6 (5.2) 28.0 (5.1)
Pre-pregnancy weight: Mean (SD)   64.7 (13.7) 66.5 (14.9)
Weight at delivery: Mean (SD)   79.7 (13.9) 81.0 (14.9)
Infant Gender
  Male 51.0% 50.6%
  Female 49.0% 49.4%
Nulliparous
  Yes 45.3% 42.7%
  No 54.7% 57.3%
Smoking at delivery
  Yes 24.9% 25.8%
  No 75.1% 74.2%
Pregnancy complications
  Yes 3.9 % 4.1 %
  No 96.1 % 95.9 %
Income Quintile
  1 21.6% 17.0%
  2 20.0% 20.7%
  3 19.9% 20.2%
  4 21.4% 21.9%
  5 17.1% 20.9%
Urban/Rural residence
  Urban 74.7% 70.6%
  Rural 25.3% 29.4%