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
 Alcohol during pregnancy
 Placental ischemia and other hypoxia
 Other biological determinants
 Delivery mode
 Gestational agea
  Late preterm7.37.1
  Early term28.728.5
  Full term64.064.4
Neonatal and infant variables
 Neonatal special careb
  ≤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
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
 Parenting effectiveness
 Parenting consistency
Other covariates
 Child gender
  • 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.