Table I.
Age-standardized characteristics of participants in the Nurses' Health Study II at the midpoint of follow-up (1995).
| Laparoscopically confirmed endometriosis |
||
|---|---|---|
| No (n = 22 581) | Yes (n = 658) | |
| Age (years)a | 36.2 (2.5) | 36.5 (2.4) |
| Age at menarche (years) | ||
| Menarche <11, % | 22 | 26 |
| Menarche 12–13, % | 58 | 57 |
| Menarche ≥14, % | 20 | 17 |
| Regular menstruation at ages 18–22, % | 76 | 71 |
| Irregular menstruation at ages 18–22, % | 21 | 24 |
| Hirsutism, % | 1 | 2 |
| Nulliparous, % | 9 | 15 |
| Ever OC use, % | 86 | 95 |
| BMI at age 18 (kg/m²) | 21.0 (2.9) | 21.0 (3.0) |
| BMI <18.5 at age 18, % | 14 | 16 |
| BMI 18.5 to <22.5 at age 18, % | 64 | 61 |
| BMI 22.5 to <25.0 at age 18, % | 14 | 15 |
| BMI 25.0+ at age 18, % | 8 | 8 |
| Current BMI (kg/m²) | 24.7 (5.1) | 25.1 (5.1) |
| BMI <18.5, % | 2 | 2 |
| BMI 18.5 to <22.5, % | 36 | 34 |
| BMI 22.5 to <25.0, % | 23 | 22 |
| BMI 25.0 to <30.0, % | 22 | 23 |
| BMI 30.0+, % | 13 | 16 |
| Total physical activity (METS/week) | 21.8 (27.8) | 23.0 (34.3) |
| Never smoker, % | 72 | 66 |
| Former smoker, % | 20 | 20 |
| Current smoker, % | 8 | 13 |
| AHEI score | 47.4 (9.6) | 46.8 (9.8) |
| Alcohol intake (grams/day) | 3.1 (5.8) | 2.8 (6.0) |
| Any analgesic 2+ or more times per week, % | 39 | 46 |
| Any screening behavior, % | 84 | 88 |
| White, % | 93 | 95 |
Values are means (SD) or percentages and are standardized to the age distribution of the study population.
OC, oral contraceptive; METS, metabolic equivalent task score; AHEI, alternative health eating index.
aValue is not age-adjusted.