Table 1

Descriptive statistics by maternal exposure to stressful life events prior to conception and infant birth weight status, national data from the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B), 2001–2003

TotalStressful life events prior to conceptionInfant birth weight status
NoneAnyp ValueVery lowNormalp Value
Total (weighted)3 182 8402 577 421605 41944 7323 138 108
Per cent81.0%19.0%1.4%98.6%
Total (unweighted)*6900545014009005950
Infant birth weight status<0.001
 Very low1.4%1.2%2.1%100.0%
 Normal98.6%98.8%97.9%100.0%
Stressful life events prior to conception<0.001
 None81.0%100.0%71.4%81.1%
 Any19.0%100.0%28.6%18.9%
Health, stress and sociodemographic factors
Pregnancy complications0.36<0.001
 None87.4%87.7%86.6%57.0%87.9%
 Any12.6%12.3%13.4%43.0%12.1%
Maternal chronic conditions0.23<0.001
 None80.1%80.5%78.5%60.8%80.4%
 Any19.9%19.5%21.5%39.2%19.6%
Maternal health status, mean (SD)†2.0 (0.95)2.0 (0.95)2.1 (0.97)0.802.3 (3.1)2.0 (0.89)<0.001
Pre-pregnancy body mass index0.290.01
 Normal, underweight or unknown56.2%56.5%54.5%51.2%56.2%
 Overweight or obese43.8%43.5%45.5%48.8%43.8%
Initiation of prenatal care0.22<0.001
 In the first trimester95.5%95.5%95.3%93.6%95.5%
 In the second or third trimester4.2%4.2%4.0%4.5%4.2%
 Did not receive prenatal care0.3%0.3%0.7%1.9%0.3%
Plurality<0.001<0.001
 Singleton98.8%99.1%97.7%81.7%99.1%
 Multiple1.2%0.9%2.3%18.3%0.9%
Parity<0.0010.01
 None41.0%44.8%24.8%44.9%41.0%
 One or more59.0%55.2%75.2%55.1%59.0%
Stressful life events during pregnancy0.020.66
 None94.1%93.8%95.6%93.7%94.2%
 Any5.9%6.2%4.4%6.3%5.8%
Maternal age, years, mean (SD)27.2 (6.1)26.3 (5.8)30.8 (6.2)<0.00127.1 (19.7)27.2 (5.7)0.85
Maternal race/ethnicity0.01<0.001
 Non-Hispanic white57.0%56.1%61.0%46.0%57.2%
 Non-Hispanic black14.3%14.3%13.9%27.5%14.1%
 Non-Hispanic Asian/Pacific Islander3.6%3.7%3.1%2.8%3.6%
 Non-Hispanic other race2.6%2.5%3.1%2.1%2.6%
 Hispanic22.5%23.3%18.9%21.7%22.5%
Marital status<0.001<0.001
 Married or living with partner83.4%83.1%84.7%76.7%83.5%
 Separated/divorced/widowed3.1%2.5%5.6%3.1%3.1%
 Never married13.5%14.4%9.7%20.2%13.4%
Health insurance0.10<0.001
 Private only58.9%58.2%62.0%51.6%59.0%
 Any public37.5%38.3%34.2%44.6%37.4%
 None3.6%3.5%3.8%3.8%3.5%
Socioeconomic status, mean (SD)‡−0.08 (0.81)−0.09 (0.82)−0.04 (0.80)0.20−0.25 (2.4)−0.08 (0.76)<0.001
Region of residence0.300.01
 Northeast17.0%17.2%15.8%17.7%17.0%
 Midwest22.2%22.2%22.0%21.0%22.2%
 South36.9%36.3%39.6%42.1%36.8%
 West24.0%24.3%22.7%19.2%24.0%
  • Weighted estimates. p Values derived from t tests for continuous variables and χ2 tests for categorical variables. National Center for Education Statistics (NCES) rounding rules applied to unweighted Ns.

  • *Unweighted subgroup Ns may not add to the total due to rounding.

  • †Self-reported health was measured on a five-point Likert scale with higher scores indicating worse health.

  • ‡Higher scores indicate higher socioeconomic status.