Table. Baseline Characteristics of UK Biobank Participants by Age at Menarche.
| Baseline characteristic | Age at menarche (in completed full-year intervals), ya | |||||
|---|---|---|---|---|---|---|
| <12 (n = 53 058) | 12 (n = 50 117) | 13 (n = 64 513) | 14 (n = 52 211) | 15 (n = 29 058) | ≥16 (n = 15 589) | |
| Age, mean (SD), y | 56.7 (7.7) | 56.3 (7.9) | 56.0 (8.0) | 56.5 (8.1) | 56.6 (8.1) | 56.0 (8.1) |
| Race/ethnicity, No. (%) | ||||||
| White European | 50 445 (95.1) | 47 418 (94.6) | 61 201 (94.9) | 49 616 (95.0) | 27 355 (94.1) | 14 091 (90.4) |
| Mixed | 399 (0.8) | 342 (0.7) | 425 (0.7) | 311 (0.6) | 181 (0.6) | 118 (0.8) |
| Asian | 844 (1.6) | 971 (1.9) | 1227 (1.9) | 1017 (1.9) | 608 (2.1) | 547 (3.5) |
| Black | 754 (1.4) | 778 (1.6) | 915 (1.4) | 726 (1.4) | 584 (2.0) | 549 (3.5) |
| Other | 448 (0.8) | 483 (1.0) | 582 (0.9) | 427 (0.8) | 278 (1.0) | 237 (1.5) |
| BMI, mean (SD) | 28.57 (5.7) | 27.35 (5.2) | 26.71 (4.9) | 26.50 (4.8) | 26.37 (4.8) | 26.22 (4.9) |
| Current smoker, No. (%) | 4866 (9.2) | 4083 (8.1) | 5292 (8.2) | 4669 (8.9) | 2940 (10.1) | 1796 (11.5) |
| Current alcohol consumption, No. (%) | 47 731 (90.0) | 45 729 (91.2) | 59 003 (91.5) | 47 436 (90.9) | 25 989 (89.4) | 13 571 (87.1) |
| Townsend deprivation index, mean (SD) | −1.3 (3.0) | −1.5 (3.0) | −1.4 (3.0) | −1.4 (3.0) | −1.2 (3.1) | −0.9 (3.3) |
| Physical activity level, No. (%) | ||||||
| Low | 29 992 (56.5) | 28 357 (56.6) | 36 033 (55.9) | 28 764 (55.1) | 15 839 (54.5) | 8465 (54.3) |
| Moderate | 20 680 (39.0) | 19 693 (39.3) | 25 773 (40.0) | 21 119 (40.4) | 11 800 (40.6) | 6208 (39.8) |
| High | 2386 (4.5) | 2067 (4.1) | 2707 (4.2) | 2328 (4.5) | 1419 (4.9) | 916 (5.9) |
| Healthy diet score, mean (SD) | 2.0 (1.1) | 1.9 (1.1) | 1.9 (1.1) | 1.8 (1.1) | 1.8 (1.1) | 1.9 (1.1) |
| Postmenopausal, No. (%) | 10 784 (20.3) | 11 641 (23.2) | 16 211 (25.1) | 12 572 (24.1) | 6884 (23.7) | 3925 (25.2) |
| Parity, mean (SD) | 2.8 (1.1) | 2.7 (1.1) | 2.8 (1.1) | 2.8 (1.1) | 2.9 (1.1) | 2.8 (1.2) |
| Birth weight, mean (SD), kg | 3.2 (0.7) | 3.2 (0.6) | 3.3 (0.6) | 3.3 (0.6) | 3.2 (0.7) | 3.2 (0.7) |
| History of disease, No. (%) | ||||||
| Cancer | 5235 (9.9) | 4700 (9.4) | 5633 (8.7) | 4699 (9.0) | 2538 (8.7) | 1312 (8.4) |
| CVD | 2218 (4.2) | 1555 (3.1) | 1863 (2.9) | 1739 (3.3) | 1123 (3.9) | 649 (4.2) |
| Diabetes | 2699 (5.1) | 1911 (3.8) | 2093 (3.2) | 1713 (3.3) | 978 (3.4) | 637 (4.1) |
| Hypertension | 28 538 (53.79) | 24 884 (49.65) | 29 982 (46.47) | 24 693 (47.29) | 13 651 (46.98) | 7137 (45.78) |
| High cholesterol | 8555 (16.1) | 6982 (13.9) | 8031 (12.4) | 6949 (13.3) | 4146 (14.3) | 2207 (14.2) |
| GRS of age at menarche | ||||||
| No. | 41 097 | 41 120 | 41 096 | 41 125 | 41 120 | 41 118 |
| Mean (SD) | 309.0 (10.5) | 311.4 (10.4) | 313.5 (10.4) | 315.2 (10.4) | 316.9 (10.5) | 318.6 (10.6) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); CVD, cardiovascular disease; GRS, genetic risk score.
a
Missing data were coded as mean values for continuous variables, with another category for categorical variables.