Table 2.
Participants’ characteristics (n=3038)
| Child characteristics | N | Mean (SD)a |
|---|---|---|
| Sex, % | ||
| Male | 1566 | 52 |
| Female | 1472 | 48 |
| Missing | 0 | 0 |
| Gestational age, week | 3038 | 39 (34, 41) |
| Birthweight, gram | 3038 | 3195 (682) |
| Mode of delivery, % | ||
| Cesarean section | 1421 | 48 |
| Vaginal delivery | 1617 | 53 |
| Missing | 0 | 0 |
| Maternal Characteristics | ||
| Age, year | 3038 | 31.1 (5.9) |
| Parity, % | ||
| Nulliparous | 1387 | 46 |
| Other | 1628 | 54 |
| Missing | 0 | 0 |
| Race/ethnicity, % | ||
| Non-Hispanic White | 2541 | 84 |
| Not White or Other | 497 | 16 |
| Missing | 0 | 0 |
| Educational levels, % | ||
| Less than high school | 128 | 4 |
| High school equivalent | 326 | 11 |
| Some college | 869 | 29 |
| College graduate | 747 | 24 |
| Graduate/professional school | 968 | 32 |
| Missing | 0 | 0 |
| Private health insurance, % | ||
| Yes | 2413 | 80 |
| No | 623 | 20 |
| Missing | 0 | 0 |
| Smoking in pregnancy, % | ||
| Yes | 346 | 11 |
| No | 2691 | 89 |
| Missing | 0 | 0 |
| Alcohol consumption during pregnancy, % | ||
| Yes | 413 | 14 |
| No | 2624 | 86 |
| Missing | 1 | 0.0 |
| Pre-pregnancy body mass index | 3032 | 27.0 (6.8) |
| Infertility treatment, % | ||
| Assisted Reproductive Technology | 475 | 16 |
| Ovulation Induction/Intrauterine Insemination | 498 | 16 |
| No | 2064 | 68 |
| Missing | 1 | 0 |
a
Numbers are mean (standard deviation) for continuous normally distributed variables (birthweight, maternal age and pre-pregnancy body mass index), median (90% range) for continuous variables with skewed distribution (gestational age), and percentage for categorical variables.
Observations counted from singletons (n=2400) and one randomly selected twin of each pair (n=638).