Table 4. Variables selected to be associated with MR/DD1 by backward elimination2 and parameter estimates by the logistic regression model.
| Variables | Level3 | Estimate4 | 95% Confidence Interval | P-value5 |
|---|---|---|---|---|
| Intercept | -3.568 | (-3.890, -3.246) | <0.001 | |
| Child gender | Female | -0.780 | (-0.912, -0.647) | <0.001 |
| Mother's race | African-American | 0.113 | (-0.023, 0.250) | 0.103 |
| Other | -0.716 | (-1.277, -0.155) | 0.012 | |
| SGA | Yes | 0.244 | (0.064, 0.423) | 0.008 |
| Parity | >= 1 | 0.297 | (0.165, 0.429) | <0.001 |
| Gestational age (weeks) | 28-36 | 0.282 | (0.099, 0.464) | 0.002 |
| < 28 | 1.349 | (0.699, 1.999) | <0.001 | |
| 2 | 0.052 | (-0.229, 0.334) | 0.715 | |
| 3 | 1.538 | (1.147, 1.928) | <0.001 | |
| Strip | 4 | 0.299 | (0.049, 0.550) | 0.019 |
| 5 | 0.232 | (-0.045, 0.51) | 0.101 | |
| 6 | 0.740 | (0.346, 1.135) | <0.001 | |
| Child age at last follow-up | 0.247 | (0.221, 0.272) | <0.001 | |
| As | 0.060 | (0.020, 0.100) | 0.003 | |
*
AIC = 5637.6 (Akaike Information Criterion).
1
MR/DD: mental retardation or developmental delay.
2
The eliminated variables include alcohol use during pregnancy, mother's age at delivery, Hg and Pb.
3
The missing level of each categorical variable is the statistical reference group.
4
The exponential of the parameter estimate is interpreted as odd ratio.
5
P-value is based on t test.