Table 1.
Participants’ characteristics (n=4909)
| Maternal Characteristics | n | |
|---|---|---|
| Age, years | 4909 | 30.5 (6.1) |
| Parity, primipara | 1337 | 29.4 |
| Race/ethnicity | ||
| Non-Hispanic White | 4087 | 83.3 |
| Not White or Other | 822 | 16.7 |
| Educational levels | ||
| Less than high school | 295 | 6.0 |
| High school equivalent | 633 | 12.9 |
| Some college | 1497 | 30.5 |
| College graduate | 1083 | 22.1 |
| Graduate/professional school | 1401 | 28.5 |
| Private health insurance | 3675 | 74.9 |
| Married | 4166 | 88.3 |
| History of smoking | ||
| Never smoked | 3051 | 62.2 |
| Smoked previously but not during pregnancy | 1162 | 23.7 |
| Smoked during pregnancy | 694 | 14.1 |
| Alcohol consumption during pregnancy | 601 | 12.2 |
| Pre-pregnancy body mass index | 4898 | 27.1 (6.8) |
| Infertility treatment, yes | 1442 | 29.4 |
| Child characteristics | ||
| Gender, male | 2541 | 51.8 |
| Twin births | 1075 | 21.9 |
| Gestational age, week | 4909 | 39.0 (33.0-41.0) |
| Birth weight, gram | 4909 | 3177.5 (692.4) |
| Time to achieve motor milestones, month | ||
| Sitting without support | 3401 | 6.4 (4.0-8.9) |
| Standing with assistance | 3077 | 8.2 (5.4-11.8) |
| Hands-and-knees crawling | 2997 | 8.2 (5.6-11.6) |
| Walking with assistance | 2783 | 9.6 (6.8-13.3) |
| Standing alone | 2401 | 10.8 (7.9-14.7) |
| Walking alone | 2567 | 12.2 (9.4-17.0) |
Numbers are percentage for categorical variables, mean (SD) for continuous normally distributed variables and median (90% range) for continuous variables with skewed distribution.