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
| Total | Stressful life events prior to conception | Infant birth weight status | |||||
|---|---|---|---|---|---|---|---|
| None | Any | p Value | Very low | Normal | p Value | ||
| Total (weighted) | 3 182 840 | 2 577 421 | 605 419 | 44 732 | 3 138 108 | ||
| Per cent | 81.0% | 19.0% | 1.4% | 98.6% | |||
| Total (unweighted)* | 6900 | 5450 | 1400 | 900 | 5950 | ||
| Infant birth weight status | <0.001 | – | |||||
| Very low | 1.4% | 1.2% | 2.1% | 100.0% | – | ||
| Normal | 98.6% | 98.8% | 97.9% | – | 100.0% | ||
| Stressful life events prior to conception | – | <0.001 | |||||
| None | 81.0% | 100.0% | – | 71.4% | 81.1% | ||
| Any | 19.0% | – | 100.0% | 28.6% | 18.9% | ||
| Health, stress and sociodemographic factors | |||||||
| Pregnancy complications | 0.36 | <0.001 | |||||
| None | 87.4% | 87.7% | 86.6% | 57.0% | 87.9% | ||
| Any | 12.6% | 12.3% | 13.4% | 43.0% | 12.1% | ||
| Maternal chronic conditions | 0.23 | <0.001 | |||||
| None | 80.1% | 80.5% | 78.5% | 60.8% | 80.4% | ||
| Any | 19.9% | 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) | 0.80 | 2.3 (3.1) | 2.0 (0.89) | <0.001 |
| Pre-pregnancy body mass index | 0.29 | 0.01 | |||||
| Normal, underweight or unknown | 56.2% | 56.5% | 54.5% | 51.2% | 56.2% | ||
| Overweight or obese | 43.8% | 43.5% | 45.5% | 48.8% | 43.8% | ||
| Initiation of prenatal care | 0.22 | <0.001 | |||||
| In the first trimester | 95.5% | 95.5% | 95.3% | 93.6% | 95.5% | ||
| In the second or third trimester | 4.2% | 4.2% | 4.0% | 4.5% | 4.2% | ||
| Did not receive prenatal care | 0.3% | 0.3% | 0.7% | 1.9% | 0.3% | ||
| Plurality | <0.001 | <0.001 | |||||
| Singleton | 98.8% | 99.1% | 97.7% | 81.7% | 99.1% | ||
| Multiple | 1.2% | 0.9% | 2.3% | 18.3% | 0.9% | ||
| Parity | <0.001 | 0.01 | |||||
| None | 41.0% | 44.8% | 24.8% | 44.9% | 41.0% | ||
| One or more | 59.0% | 55.2% | 75.2% | 55.1% | 59.0% | ||
| Stressful life events during pregnancy | 0.02 | 0.66 | |||||
| None | 94.1% | 93.8% | 95.6% | 93.7% | 94.2% | ||
| Any | 5.9% | 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) | <0.001 | 27.1 (19.7) | 27.2 (5.7) | 0.85 |
| Maternal race/ethnicity | 0.01 | <0.001 | |||||
| Non-Hispanic white | 57.0% | 56.1% | 61.0% | 46.0% | 57.2% | ||
| Non-Hispanic black | 14.3% | 14.3% | 13.9% | 27.5% | 14.1% | ||
| Non-Hispanic Asian/Pacific Islander | 3.6% | 3.7% | 3.1% | 2.8% | 3.6% | ||
| Non-Hispanic other race | 2.6% | 2.5% | 3.1% | 2.1% | 2.6% | ||
| Hispanic | 22.5% | 23.3% | 18.9% | 21.7% | 22.5% | ||
| Marital status | <0.001 | <0.001 | |||||
| Married or living with partner | 83.4% | 83.1% | 84.7% | 76.7% | 83.5% | ||
| Separated/divorced/widowed | 3.1% | 2.5% | 5.6% | 3.1% | 3.1% | ||
| Never married | 13.5% | 14.4% | 9.7% | 20.2% | 13.4% | ||
| Health insurance | 0.10 | <0.001 | |||||
| Private only | 58.9% | 58.2% | 62.0% | 51.6% | 59.0% | ||
| Any public | 37.5% | 38.3% | 34.2% | 44.6% | 37.4% | ||
| None | 3.6% | 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 residence | 0.30 | 0.01 | |||||
| Northeast | 17.0% | 17.2% | 15.8% | 17.7% | 17.0% | ||
| Midwest | 22.2% | 22.2% | 22.0% | 21.0% | 22.2% | ||
| South | 36.9% | 36.3% | 39.6% | 42.1% | 36.8% | ||
| West | 24.0% | 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.