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Table 2 Characteristics of participants stratified by sex and rapid weight gain from birth to 1.5 years

From: Infant weight gain and DXA-measured adolescent adiposity: data from the Japan Kids Body-composition Study

  Boys Girls
Non-RWG (N = 137) RWG (N = 68) p value Non-RWG (N = 134) RWG (N = 84) p value
Maternal characteristics at pregnancy
 Age, years 29.7 ± 4.5 29.1 ± 4.7 0.35 29.1 ± 5.5 28.6 ± 4.6 0.52
 Gestational age, weeks 39.2 ± 1.1 38.6 ± 1.1 < 0.01 39.2 ± 1.0 38.6 ± 1.1 < 0.01
Characteristics of child at birth
 Length z-score 0.30 ± 0.8 − 0.09 ± 0.89 < 0.01 0.34 ± 0.85 − 0.05 ± 0.93 < 0.01
 Weight z-score 0.47 ± 1.0 − 0.16 ± 0.86 < 0.01 0.27 ± 0.79 − 0.47 ± 0.88 < 0.01
Characteristics of the child at age 1.5 years
 Height z-score 0.26 ± 0.8 0.82 ± 0.99 < 0.01 − 0.03 ± 0.99 0.65 ± 0.96 < 0.01
 Weight z-score 0.05 ± 0.7 1.11 ± 0.92 < 0.01 − 0.03 ± 0.79 1.03 ± 1.03 < 0.01
Change in weight z-score from 0 to 1.5 years − 0.42 ± 0.76 1.28 ± 0.46 < 0.01 − 0.30 ± 0.63 1.50 ± 0.69 < 0.01
Characteristics of the child at adolescence
 Height z-score 0.17 ± 0.86 0.62 ± 0.83 < 0.01 − 0.16 ± 0.91 0.19 ± 0.96 < 0.01
 Weight z-score 0.02 ± 0.89 0.59 ± 1.06 < 0.01 − 0.20 ± 0.94 0.32 ± 0.86 < 0.01
 BMI, kg/m2 18.8 ± 2.6 20.1 ± 3.2 < 0.01 19.2 ± 2.5 20.4 ± 2.8 < 0.01
 WC, cm 67.5 ± 7.1 71.3 ± 9.0 < 0.01 67.6 ± 6.3 70.0 ± 6.8 < 0.01
 Fat mass index, kg/m2 2.8 ± 1.5 3.4 ± 1.6 0.01 4.4 ± 1.5 5.1 ± 1.6 < 0.01
 Body fat percentage, % 14.2 ± 5.0 16.1 ± 5.3 0.01 22.4 ± 4.8 24.3 ± 4.8 < 0.01
 Lean mass index, kg/m2 15.6 ± 1.4 16.3 ± 1.9 < 0.01 14.4 ± 1.3 14.9 ± 1.4 < 0.01
 Overweight, N (%) 12 (8.8) 15 (22.1) 0.01 9 (6.7) 11 (13.1) 0.15
 Sedentary behavior, N (%)
  < 2 h 82 (59.9) 46 (67.6) 0.32 74 (55.2) 45 (53.6) 0.27
  2–3 h 30 (21.9) 15 (22.1)   42 (31.4) 21 (25.0)  
  ≥ 3 h 25 (18.2) 7 (10.3)   18 (13.4) 18 (21.4)  
 Pubic hair appearance, N (%)
  Age < 12 years 34 (24.8) 22 (32.4) 0.32 79 (59.0) 66 (78.6) < 0.01
  Age ≥ 12 years 103 (75.2) 46 (67.6)   55 (41.0) 18 (21.4)  
 Size for gestational age, N (%)
  SGA 3 (2.2) 7 (10.3) < 0.01 1 (0.7) 9 (10.7) < 0.01
  AGA 100 (73.0) 51 (75.0)   101 (75.4) 65 (77.4)  
  LGA 34 (24.8) 10 (14.7)   32 (23.9) 10 (11.9)  
  1. Data are expressed as mean ± standard deviation or number (proportion in %)
  2. N number, SGA small for gestational age, AGA appropriate for gestational age, LGA large for gestational age, BMI body mass index, WC waist circumference, RWG rapid weight gain