TABLE 1

Weighted Sample Characteristics for Developmental Delay Analysis (2–3 y of Age; N = 15 099) and Receptive Vocabulary Delay Analysis (4–5 y of Age; N = 12 203)

Weighted % With Characteristic at 2–3 y of AgeWeighted % With Characteristic at 4–5 y of Age
Perinatal variables
 Smoking during pregnancy
  Yes18.218.3
  No81.881.7
 Alcohol during pregnancy
  Yes15.615.8
  No84.484.2
 Placental ischemia and other hypoxia
  Yes12.612.6
  No87.487.4
 Other biological determinants
  Yes6.46.4
  No93.693.6
 Delivery mode
  Cesarean19.119.1
  Vaginal80.980.9
 Gestational agea
  Late preterm7.37.1
  Early term28.728.5
  Full term64.064.4
Neonatal and infant variables
 Neonatal special careb
  Yes8.58.3
  No91.591.7
 Breastfeeding
  None16.916.6
  ≤6 mo45.645.5
  >6 mo37.537.9
Social context: family structure
 Partnership status
  Single-parent family8.97.1
  Any transition in partnership status6.011.9
  2-parent family85.181.0
 Number of siblings
  ≥37.28.2
  1–267.075.7
  None25.816.1
Social context: family resources
 Family income adequacy
  Any period of inadequacy18.320.0
  Consistently adequate81.780.0
 Current maternal education
  Secondary or less30.632.0
  Some postsecondary18.414.8
  College or university degree51.053.2
 Maternal age (at birth of child)
  <20 y3.83.8
  ≥20 y96.296.2
 Maternal health
  Any period of poor health7.310.4
  Consistently good92.789.6
 Maternal mental health
  Any period of depression10.410.8
  Consistently not depressed89.689.2
Social context variables: other
 Family functioning
  Poor functioning10.910.4
  Not poor functioning89.189.6
Proximal social processes
 Parenting interactions
  Negative10.411.1
  Positive89.688.9
 Parenting effectiveness
  Ineffective9.19.8
  Effective90.990.2
 Parenting consistency
  Inconsistent9.310.3
  Consistent90.789.7
Other covariates
 Child gender
  Male51.250.8
  Female48.849.2
  • Percentages are adjusted for missing data. Missingness varied from 0.0% to 11.3% for any given variable.

  • a Because of exclusions, gestational ages of late preterm, early term, and full term cover 100% of the study sample.

  • b Special care includes NICU admission, hospital transfer, and use of ventilation.