TABLE 1.
Characteristics* associated with birth weight, fetal growth (birth-weight-for-gestational-age z value), or length of gestation among 2,109 pregnant women from Massachusetts enrolled in Project Viva, 1999–2002
| Characteristic | %† of subjects | Difference in birth weight (g)
|
Difference in fetal growth (z value)
|
Difference in length of gestation (days)
|
|||
|---|---|---|---|---|---|---|---|
| Mean | 95% CI‡ | Mean | 95% CI | Median | 95% CI | ||
| Maternal height (m) | |||||||
| <1.6 | 19 | −241 | −312, −170 | −0.46 | −0.58, −0.34 | −0.4 | −1.8, 1.0 |
| 1.6–<1.65 | 26 | −166 | −230, −104 | −0.36 | −0.46, −0.26 | 0.1 | −1.2, 1.3 |
| 1.65–<1.7 | 26 | −60 | −123, 3 | −0.15 | −0.26, −0.05 | 1.5 | 0.3, 2.8 |
| ≥1.7 (referent) | 29 | ||||||
| Gestational weight gain§ | |||||||
| Low | 15 | −149 | −222, −87 | −0.17 | −0.29, −0.05 | −0.5 | −2.0, 0.9 |
| Normal (referent) | 35 | ||||||
| High | 49 | 169 | 115, 222 | 0.24 | 0.15, 0.33 | 1.9 | 0.8, 3.0 |
| Prepregnancy body mass index (kg/m2)§ | |||||||
| Underweight (<19.8) | 13 | −18 | −91, 56 | −0.09 | −0.21, 0.03 | −1.0 | −2.5, 0.5 |
| Normal (19.8–26.0) (referent) | 56 | ||||||
| Overweight (>26.0–29.0) | 12 | 65 | −11, 140 | 0.19 | 0.06, 0.31 | −1.0 | −2.5, 0.5 |
| Obese (>29.0) | 19 | 63 | −3, 129 | 0.21 | 0.10, 0.32 | −0.5 | −1.8, 0.9 |
| Infant sex female (vs. male) | 48 | −138 | −184, −91 | −0.33 | −0.41, −0.26 | 0.2 | −0.8, 1.1 |
| Maternal age (years) | |||||||
| 14–<20 | 3 | −164 | −319, −9 | −0.29 | −0.54, −0.03 | −1.7 | −4.7, 1.4 |
| 20–<25 | 6 | −64 | −170, 43 | −0.20 | −0.37, −0.02 | 1.6 | −0.5, 3.7 |
| 25–<30 | 21 | −55 | −118, 8 | −0.13 | −0.24, −0.03 | 0.8 | −0.5, 2.0 |
| 30–<35 (referent) | 42 | ||||||
| 35–<40 | 23 | 17 | −44, 78 | 0.02 | −0.08, 0.12 | −0.1 | −1.3, 1.1 |
| ≥40 | 4 | −59 | −179, 61 | −0.17 | −0.37, 0.03 | −0.4 | −2.8, 2.0 |
| Smoked during pregnancy (vs. no) | 10 | −72 | −150, 6 | −0.15 | −0.28, −0.03 | 0.6 | −1.0, 2.2 |
| Gravidity >1 (vs. 1) | 70 | 105 | 51, 160 | 0.22 | 0.13, 0.31 | −1.4 | −2.5, −0.3 |
| Maternal race/ethnicity | |||||||
| Asian | 6 | −244 | −348, −139 | −0.28 | −0.45, −0.11 | −3.4 | −5.5, −1.3 |
| Black | 16 | −178 | −251, −104 | −0.26 | −0.38, −0.14 | −1.9 | −3.4, −0.5 |
| Hispanic | 7 | −62 | −159, 35 | −0.05 | −0.21, 0.11 | −2.0 | −3.9, −0.1 |
| Other | 4 | −25 | −151, 101 | −0.00 | −0.21, 0.20 | −0.3 | −2.8, 2.3 |
| Non-Hispanic White (referent) | 66 | ||||||
| Education | |||||||
| High school or less | 12 | −45 | −135, 45 | −0.13 | −0.28, 0.02 | −0.5 | −2.3, 1.2 |
| Some college | 23 | −28 | −95, 38 | −0.11 | −0.22, −0.0 | 0.3 | −1.0, 1.7 |
| College graduate (referent) | 35 | ||||||
| Graduate degree | 29 | 9 | −50, 69 | −0.04 | −0.14, 0.06 | 1.6 | 0.4, 2.8 |
*
Estimates of effect were simultaneously adjusted for all other characteristics in the table as well as for site of study enrollment.
†
Percentages may not total 100 because of some missing values.
‡
CI, confidence interval.
§
Per 1990 Institute of Medicine guidelines (23).