Table I.
Characteristics of participants (pregnancies) by body mass index and waist-to-hip ratio at baseline, Black Women's Health Study, 1995–2011.
| Characteristic | Body mass index in 1995 |
Waist-to-hip ratio in 1995 |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| <18.5 (n = 76) | 18.5–24 (n = 1322) | 25–29 (n = 523) | 30–34 (n = 189) | ≥35 (n = 123) | <0.71 (n = 420) | 0.71–0.74 (n = 384) | 0.75–0.77 (n = 369) | 0.78–0.84 (n = 404) | ≥0.85 (n = 318) | |
| Age at baseline (years), mean | 25.8 | 26.7 | 27.6 | 27.3 | 27.3 | 26.8 | 27.7 | 27.0 | 27.2 | 26.4 |
| Age at pregnancy attempt (years), mean | 34.7 | 34.0 | 34.0 | 33.7 | 34.3 | 33.8 | 34.5 | 34.0 | 33.9 | 33.9 |
| Year of pregnancy attempt: 1995–99, % | 22 | 35 | 46 | 43 | 42 | 36 | 42 | 39 | 41 | 34 |
| Year of pregnancy attempt: 2000–04, % | 41 | 41 | 34 | 36 | 35 | 42 | 38 | 37 | 37 | 37 |
| Year of pregnancy attempt: 2005–11, % | 37 | 25 | 20 | 21 | 23 | 22 | 20 | 24 | 22 | 29 |
| Parous at time of attempt, % | 45 | 46 | 46 | 45 | 44 | 44 | 45 | 45 | 47 | 46 |
| Current smoker, % | 4 | 4 | 5 | 6 | 10 | 2 | 5 | 5 | 5 | 4 |
| Former smoker, % | 5 | 6 | 9 | 6 | 17 | 6 | 8 | 6 | 9 | 6 |
| ≥7 drinks/week, % | 5 | 3 | 3 | 3 | 1 | 3 | 3 | 2 | 2 | 3 |
| Waist circumference (inches), mean | 25.2 | 27.7 | 32.0 | 34.6 | 39.2 | 26.7 | 27.9 | 29.4 | 31.3 | 34.3 |
| Waist to hip ratio, mean | 0.7 | 0.8 | 0.8 | 0.8 | 0.8 | 0.7 | 0.7 | 0.8 | 0.8 | 0.9 |
| BMI (kg/m2), mean | 17.9 | 22.0 | 27.1 | 32.1 | 40.4 | 23.8 | 23.4 | 24.1 | 25.6 | 27.6 |
| Polycystic ovary syndrome, % | 3 | 2 | 2 | 3 | 5 | 1 | 2 | 3 | 2 | 4 |
| Age at menarche (years), mean | 12.8 | 12.4 | 12.1 | 11.6 | 11.8 | 12.2 | 12.3 | 12.1 | 12.2 | 12.3 |
| Education (years), mean | 15.8 | 15.8 | 15.7 | 15.6 | 15.4 | 15.8 | 15.8 | 15.9 | 15.7 | 15.5 |
| Northeast, % | 33 | 28 | 32 | 25 | 35 | 29 | 27 | 26 | 28 | 33 |
| West, % | 14 | 19 | 14 | 13 | 8 | 18 | 22 | 17 | 12 | 14 |
| Midwest, % | 26 | 18 | 21 | 20 | 22 | 21 | 17 | 19 | 22 | 16 |
| South, % | 27 | 35 | 33 | 43 | 35 | 32 | 35 | 38 | 38 | 37 |
| Total MET-hours/week, mean | 25 | 28 | 28 | 24 | 21 | 30 | 29 | 26 | 22 | 26 |
| Income in 2003: ≤$50 000, % | 32 | 14 | 19 | 16 | 33 | 14 | 17 | 14 | 14 | 24 |
| Income in 2003: $50 001–$100 000, % | 30 | 41 | 45 | 47 | 39 | 39 | 39 | 42 | 48 | 42 |
| Income in 2003: >$100 000, % | 35 | 36 | 27 | 25 | 23 | 38 | 37 | 32 | 27 | 26 |
Characteristics were ascertained at baseline (1995) unless otherwise noted. Means or percentages are standardized to the age distribution of cohort in 1995 (with the exception of age). Percentages do not sum to 100% for variables with missing data. Participants are included more than once if they had several births during 1995–2011. There were 344 (15%) missing values for waist-to-hip ratio in 1995. MET, metabolic equivalents.