TABLE 3

Distribution of Select Characteristics Among Respondents and Nonrespondents in the Y6FU, Based on Information From the IFPSII

CharacteristicParticipants in the Y6FU (N = 1542), %Nonparticipants in the Y6FU (N = 1416), %χ2 Probability
Maternal characteristics
 Age (y)<.001
  18–2415.131.4
  25–3465.158.5
  35–4319.810.1
 Marital status<.001
  Married or cohabiting83.773.9
  Other16.326.1
 Education<.001
  High school or less16.625.8
  Some college37.243.4
  College graduate46.230.8
 Income (% of poverty threshold)<.001
  <185%35.248.9
  185–<350%37.933.7
  ≥350%26.917.4
 Employment status (prenatal).30
  Employed67.065.2
  Not employed33.034.8
 Parity.37
  128.329.8
  242.239.6
  ≥329.530.6
 Race and ethnicity<.01
  White86.681.8
  Black3.76.1
  Hispanic5.67.0
  Other4.15.1
 Region<.001
  West19.720.6
  Midwest31.128.7
  South29.735.5
  Northeast19.515.2
 Prenatal smoking<.001
  Yes7.412.2
  No92.687.8
 Prenatal care, initial visit (wk)<.01
  <1390.687.0
  13–246.17.9
  ≥253.35.1
 Returned to work when infant was ≤6 wk old.29
  Yes14.316.0
  No85.784.0
 Prepregnancy BMI.48
  Underweight (<18.5)4.35.2
  Normal wt (18.5–24.9)44.745.7
  Overweight (25.0–29.9)26.326.0
  Obese (≥30.0)24.723.1
 Number of postnatal questionnaires returned<.001
  1–725.553.2
  8–1074.546.8
Infant characteristics
 Gender.60
  Male50.049.0
  Female50.051.0
 Breastfeeding initiation.18
  Yes86.284.5
  No13.815.5
 Breastfeeding durationa (wk)<.001
  <320.724.3
  3–17.119.525.7
  ≥17.229.720.3
  Breastfeeding at last questionnaire30.129.7
 WIC participation<.001
  Yes31.949.7
  No68.150.3
 Food allergy.17
  Yes22.920.5
  No77.179.5
 Birth wt (lb).06
  <863.066.3
  ≥837.033.7
 Gestational age (wk).37
  <3934.436.0
  ≥3965.664.0
  • WIC, Special Supplemental Nutrition Program for Women, Infants, and Children.

  • a Breastfeeding duration was divided into categories by tertile among those with a value (ie, those that were not censored), and the censored cases formed a fourth category.