Table 1.
Sample descriptive statistics
| Covariates | Mean (SE) | Range | n (%) |
|---|---|---|---|
| Breastfeeding, mo | 5.07 (0.30) | 0.0-36.0 | - |
| Maternal menarcheal age, y | 12.75 (0.07) | 9.0-18.0 | - |
| Child race/ethnicity | |||
| Asian (%) | - | - | 5 (1.2) |
| African American (%) | - | - | 47 (11.0) |
| Latina (%) | - | - | 21 (4.9) |
| Other (%) | - | - | 16 (3.8) |
| White (%) | - | - | 337 (79.1) |
| Prepubertal variablesa | |||
| Gestational age, wk | 39.23 (0.07) | 34.0-42.0 | - |
| Preterm, <37 weeks (%) | - | - | 15 (3.5) |
| Birthweight, kg | 3.42 (0.02) | 2.0-5.3 | - |
| Weight, 15 mo, kg | 10.45 (0.06) | 8.0-14.4 | - |
| Infancy weight gain, % | 210.53 (2.32) | 114.5-379.8 | - |
| 24 mo | |||
| BMIP | 52.95 (1.33) | 0.4-99.6 | - |
| Overweight (%) | - | - | 40 (9.4) |
| Obese (%) | - | - | 19 (4.5) |
| 36 mo | |||
| BMIP | 55.32 (1.34) | 1.9-99.7 | - |
| Overweight (%) | - | - | 56 (13.1) |
| Obese (%) | - | - | 20 (4.7) |
| 54 mo | |||
| BMIP | 60.95 (1.31) | 0.2-99.6 | - |
| Overweight (%) | - | - | 60 (14.1) |
| Obese (%) | - | - | 39 (9.2) |
| Grade 1, mean age 6.9 (0.29) | |||
| BMIP | 61.92 (1.26) | 3.8-99.6 | - |
| Overweight, % | - | - | 54 (12.7) |
| Obese, % | - | - | 37 (8.7) |
| Pubertal onset variablesb | Median (SE) | 95% CI | |
| Menarcheal age, y | 12.67 (0.01) | 12.434-12.909 | - |
| Breast onset, TS II | 9.97 (0.02) | 9.622-10.340 | - |
| Pubic hair onset, TS II | 10.57 (0.01) | 10.301-10.850 | - |
Abbreviations: BMIP, body mass index percentile; TS, Tanner stage.
a Infancy weight gain was calculated as the difference in weight in kilograms (15 mo minus birthweight) divided by birthweight. Categories of overweight and obese were defined by BMIP values between 85 and 94.9 and 95+, respectively.
b Median ages for the pubertal onset variables were estimated from accelerated failure time models adjusted for covariates (breastfeeding, maternal menarcheal age, and child race/ethnicity).