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Table 1 Maternal and girls’ characteristics by breastfeeding duration: KPNC puberty study

From: Breastfeeding and timing of pubertal onset in girls: a multiethnic population-based prospective cohort study

Breastfeeding duration Not breastfed < 6 months ≥6 months P- value
N = 3331 (mother-daughter pairs) 511 1123 1697
Maternal characteristics N (%) or Mean (SD)  
 Age at delivery (years) 29.3 (5.7) 30.3 (5.4) 31.3 (5.1) < 0.001
 Maternal BMI (kg/mm2)
  < 25 179 (37.0) 474 (43.7) 736 (46.6) < 0.001
  25- < 30 137 (28.3) 355 (32.7) 486 (30.8)  
  ≥ 30 168 (34.7) 256 (23.6) 356 (22.6)  
 Race/Ethnicity
  Non-Hispanic White 171 (33.5) 434 (38.7) 797 (47.0) < 0.001
  Asian/Pacific Islander 127 (24.9) 307 (27.3) 363 (21.4)  
  Hispanic 149 (29.2) 294 (26.2) 439 (25.9)  
  African American 64 (12.5) 88 (7.8) 98 (5.8)  
 Parity
  0 204 (39.9) 504 (44.9) 686 (40.4) 0.02
  1 179 (35.0) 405 (36.1) 654 (38.5)  
  2+ 128 (25.1) 214 (19.1) 357 (21.0)  
 Education
  High school or less 190 (37.2) 342 (30.5) 400 (23.6) < 0.001
  Some college 187 (36.6) 375 (33.4) 478 (28.2)  
  College/university 93 (18.2) 281 (25.0) 513 (30.2)  
  Postgraduate 41 (8.0) 125 (11.1) 306 (18.0)  
Girls’ characteristics N (%) or Mean (SD)  
 Prepubertal BMI
  ≥ 85th percentile 180 (35.2) 355 (31.6) 469 (27.6) < 0.01
  1. BMI Body mass index, SD Standard deviation