Table 1.
Maternal characteristics | NHBCSa | RICHSa |
---|---|---|
Smoking during pregnancy | ||
Any | 21 (6.1%) | 19 (13.5%) |
None | 322 (93.9%) | 122 (86.5%) |
Educational attainment | ||
High school or less | 37 (10.8%) | 34 (24.1%) |
More than high school | 306 (89.2%) | 107 (75.9%) |
Ethnicity | ||
Not white | 6 (1.7%) | 36 (25.5%) |
White | 337 (98.3%) | 105 (74.5%) |
Infant characteristics | ||
Gestational age (weeks) | 38.95 (1.54) | 39.33 (1.00) |
Birth weight (g)b | 3435.14 (510.95) | 3623.09 (716.03) |
Size for gestational ageb | ||
SGA | 15 (4.4%) | 21 (14.9%) |
AGA | 292 (86.1%) | 68 (48.2%) |
LGA | 32 (9.4%) | 52 (36.9%) |
Sex | ||
Female | 159 (46.4%) | 68 (48.2%) |
Male | 184 (53.6%) | 73 (51.8%) |
Placental Cd (ng/g)c | ||
Overall | 3.13 (2.61) | 4.37 (2.71) |
Below cohort-specific median | 2.07 (1.05) | 2.78 (1.35) |
Above cohort-specific median | 4.68 (2.32) | 5.49 (2.44) |
Note: AGA, adequate for gestational age; Cd, cadmium; LGA, large for gestational age; NHBCS, New Hampshire Birth Cohort Study; RICHS, Rhode Island Child Health Study; SGA, small for gestational age.
Means and standard deviations are presented for continuous variables, whereas frequencies and percentages are presented for categorical variables.
Four samples were missing for birth weight and SGA/AGA/LGA classifications in the NHBCS; all other continuous and categorical variables had no missing values.
Medians and interquartile ranges (IQRs) presented owing to skewed distributions of Cd concentrations.