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Table 2 Characteristics of participants included and excluded from analysis (data as mean ± SD or N (%))

From: Maternal and cord blood vitamin D level and the infant gut microbiota in a birth cohort study

  Included in analysis subset  
Covariate No (N = 759) Yes (N = 499) p-value*
Maternal age (years) 29.2 ± 5.2 30.1 ± 5.2 0.002
Maternal race
 White 150 (19.8%) 140 (28.1%) 0.001
 Black 497 (65.5%) 281 (56.3%)
 Other 112 (14.8%) 78 (15.6%)
Mother married
 No 318 (41.9%) 167 (33.5%) 0.003
 Yes 441 (58.1%) 332 (66.5%)
Urban residence
 No 299 (39.4%) 256 (51.3%) <.001
 Yes 460 (60.6%) 243 (48.7%)
Household income
 < $40,000 328 (43.2%) 149 (29.9%) <.001
 $40,000–$80,000 210 (27.7%) 137 (27.5%)
 $80,000+ 139 (18.3%) 144 (28.9%)
 Refused/did not answer 82 (10.8%) 69 (13.8%)
Gestational agea 38.7 ± 1.8 38.8 ± 1.6 0.27
Birthweight z-scoreb −0.196 ± 0.972 − 0.005 ± 1.004 0.001
First born child
 No 492 (64.8%) 306 (61.3%) 0.21
 Yes 267 (35.2%) 193 (38.7%)
Mode of delivery
 Vaginal 456 (60.6%) 328 (65.9%) 0.061
 C-Section 296 (39.4%) 170 (34.1%)
Season of birth
 Winter 156 (20.6%) 101 (20.2%) 0.53
 Spring 182 (23.9%) 103 (20.6%)
 Summer 202 (26.6%) 143 (28.7%)
 Fall 219 (28.9%) 152 (30.5%)
Environmental tobacco smoke at pre-delivery
 No 517 (68.1%) 394 (79%) <.001
 Yes 242 (31.9%) 105 (21%)
  1. *Calculated by analysis of variance for numerical covariates and chi-square test for categorical covariates
  2. aN = 737 for No and N = 495 for Yes
  3. bN = 700 for No and N = 472 for Yes