Table 3.
Linear regression models of birthweight
| Parameter | Overall Model | Model NHWhite only | Model NHBlack only | Model Hispanic only | ||||
|---|---|---|---|---|---|---|---|---|
| Estimate | Pr > |t| | Estimate | Pr > |t| | Estimate | Pr > |t| | Estimate | Pr > |t| | |
| Intercept | 3320.0 | <0.0001 | 3316.92 | <0.0001 | 3104.29 | <0.0001 | 3287.44 | <0.0001 |
| Male | 116.20 | <0.0001 | 120.70 | <0.0001 | 112.20 | <0.0001 | 100.15 | <0.0001 |
| Maternal age | ||||||||
| 15–19 | −1.15 | 0.7590 | 17.33 | 0.0004 | 1.46 | 0.8628 | −59.61 | <0.0001 |
| 20–24 | 20.13 | <0.0001 | 35.02 | <0.0001 | 15.95 | 0.0459 | −37.20 | <0.0001 |
| 30–34 | −21.85 | <0.0001 | −19.59 | <0.0001 | −34.25 | 0.0014 | −12.90 | 0.3734 |
| 35–39 | −66.47 | <0.0001 | −61.54 | <0.0001 | −99.8 | <0.0001 | −31.09 | 0.2151 |
| 40–44 | −114.32 | <0.0001 | −117.20 | <0.0001 | −129.40 | <0.0001 | 17.81 | 0.7777 |
| Birth order | ||||||||
| Second | 115.19 | <0.0001 | 119.96 | <0.0001 | 100.56 | <0.0001 | 103.40 | <0.0001 |
| Third | 114.03 | <0.0001 | 117.49 | <0.0001 | 94.34 | <0.0001 | 118.31 | <0.0001 |
| Fourth | 114.53 | <0.0001 | 102.79 | <0.0001 | 85.34 | <0.0001 | 160.18 | <0.0001 |
| Maternal education | ||||||||
| Middle school | −44.54 | <0.0001 | −86.28 | <0.0001 | −24.39 | 0.0632 | −33.17 | <0.0001 |
| Some high school | −39.37 | <0.0001 | −57.01 | <0.0001 | −31.31 | <0.0001 | −15.42 | 0.0097 |
| Some college | 26.27 | <0.0001 | 25.95 | <0.0001 | 31.75 | <0.0001 | 2.11 | 0.8000 |
| College | 62.80 | <0.0001 | 60.95 | <0.0001 | 79.14 | <0.0001 | 10.74 | 0.2986 |
| Not married | −43.32 | <0.0001 | −42.97 | <0.0001 | −54.95 | <0.0001 | −29.08 | <0.0001 |
| Tobacco Use | −225.96 | <0.0001 | −238.36 | <0.0001 | −166.17 | <0.0001 | −135.79 | <0.0001 |
| Maternal race | ||||||||
| Non-Hispanic | −223.96 | <0.0001 | ||||||
| black | ||||||||
| Hispanic | −47.89 | <0.0001 | ||||||
| Age * Birth
order interaction |
||||||||
| 15–19 * second | −79.72 | <0.0001 | −86.99 | <0.0001 | −65.73 | <0.0001 | −59.25 | 0.0003 |
| 15–19 * third | −79.78 | <0.0001 | −94.83 | <0.0001 | −64.30 | 0.0027 | −62.80 | 0.0601 |
| 15–19 * fourth | −94.18 | 0.0212 | −157.90 | 0.0710 | −85.57 | 0.1049 | 44.73 | 0.7018 |
| 20–24 * second | −48.33 | <0.0001 | −53.85 | <0.0001 | −42.46 | <0.0001 | −8.79 | 0.4748 |
| 20–24 * third | −57.19 | <0.0001 | −79.05 | <0.0001 | −37.96 | 0.0017 | 0.14 | 0.9925 |
| 20–24 * fourth | −73.65 | <0.0001 | −88.65 | <0.0001 | −45.14 | 0.0073 | −57.03 | 0.0155 |
| 30–34 * second | 16.39 | 0.0011 | 11.06 | 0.0522 | 35.66 | 0.0101 | 18.79 | 0.3120 |
| 30–34 * third | 45.79 | <0.0001 | 7.44 | <0.0001 | 55.44 | 0.0003 | 35.71 | 0.0621 |
| 30–34 * fourth | 50.53 | <0.0001 | 63.76 | <0.0001 | 58.22 | 0.0024 | 5.51 | 0.8095 |
| 35–39 * second | 25.35 | 0.0004 | 22.47 | 0.0054 | 39.92 | 0.0359 | 5.78 | 0.8570 |
| 35–39 * third | 68.00 | <0.0001 | 66.88 | <0.0001 | 83.46 | <0.0001 | 35.97 | 0.2596 |
| 35–39 * fourth | 73.58 | <0.0001 | 84.72 | <0.0001 | 98.12 | <0.0001 | 14.19 | 0.6828 |
| 40–44 * second | 28.61 | 0.0789 | 25.78 | 0.1582 | 34.39 | 0.3938 | 22.04 | 0.7798 |
| 40–44 * third | 45.56 | 0.0105 | 48.75 | 0.0174 | 33.15 | 0.4287 | 4.68 | 0.9530 |
| 40–44 * fourth | 108.86 | <0.0001 | 148.71 | <0.0001 | 95.32 | 0.0546 | −136.61 | 0.0880 |
By definition, race was not included as a covariate in the race-specific models.
Grey highlighting denotes statistical significance using α=0.01.
Reference groups=female sex, maternal age 25–29 years, married, non-smoker, first birth order, high school completed, non-Hispanic (NH) white race, interaction term 25–29 years.
*
First birth overall and each individual age category.