TABLE 1

Bivariate Analysis of the Association Between Each Variable and Infants' Risk of Having Excess Weight After 6 Months of Age

VariablesLast Weight Measured for Infants Aged >6 mo
Excess Weight: Weight-for-Age z Score > 1 (n = 246)No Excess Weight: Weight-for-Age z Score ≤ 1 (n = 1650)P
Feeding practice of primary interest over the first half of Infancy
    Breastfeeding intensity (N = 1858), %<.01
        Low (<20%)46.934.2
        Medium (20%–80%)22.418.1
        High (>80%)30.747.7
    Frequency of infant-initiated bottle emptying (N = 1461), %.01
        Rarely (low tercile)30.6940.91
        Sometimes (midtercile)30.6928.67
        Often (high tercile)38.6130.42
    Frequency of mothers' encouragement of bottle emptying (N = 1460), %.09
        Rarely (low tercile)39.6031.96
        Sometimes (midtercile)33.1735.61
        Often (high tercile)27.2332.43
Confounding variables
    Infant gender (N = 1896), %.07
        Boy43.950.1
        Girl56.149.9
    Gestational age at birth, mean (SD), wk (N = 1896)39.5 (1.3)39.4 (1.2).53
    Birth weight, mean (SD), kg (N = 1896)3.7 (0.5)3.4 (0.5)<.01
    Age at the first introduction of solid food, mean (SD), wk (N = 1895)19.1 (7.2)20.8 (7.3)<.01
    No. of sweet drinks per day over the first half of infancy, mean (SD), n/d (N = 1896)0.03 (0.14)0.02 (0.14).28
    Maternal age, mean (SD), y (N = 1895)29.3 (5.4)29.7 (5.3).24
    Parity (N = 1863), %.65
        127.729.1
        >172.370.9
    Maternal education (N = 1794), %<.01
        High school graduate or less23.517.0
        Some college42.035.2
        College graduate34.547.8
    Race/ethnicity (N = 1773), %<.01
        Non-Hispanic white83.691.6
        Non-Hispanic black6.93.5
        Hispanic9.54.9
    Income as a percentage of federal poverty index (N = 1896), mean (SD)274.4 (197.1)275.5 (196.2).93
    Prepregnancy BMI, mean (SD), kg/m2 (N = 1871)27.9 (8.4)26.5 (6.4)<.01
    No. of cigarettes mothers smoked at 3 mo postpartum, mean (SD) (N = 1715)1.45 (3.9)1.04 (3.6).12
  • P values were obtained by Student's t tests for the continuous variables and by χ 2 tests for the categorical variables.