Table 1.
Demographic Characteristics of Study Participants by Categories of Average Menstrual Cycle Length: the LIFE Study, 2005–2009
| Average Menstrual Cycle Length | Total Urinary Phytoestrogens | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Included Cohort | <26 days | ≥26 and ≤35 days | >35 days | P | Q1 | Q4 | P | ||
| n | 326 | 81 | 213 | 32 | 86 | 80 | |||
| Age, y (mean ± SD) | 31 ± 4 | 32 ± 4 | 30 ± 4 | 29 ± 5 | 0.0006 | 31 ± 4 | 31 ± 4 | 0.87 | |
| BMI, kg/m2 (mean ± SD) | 28 ± 7 | 28 ± 7 | 27 ± 7 | 31 ± 11 | 0.03 | 28 ± 7 | 27 ± 7 | 0.45 | |
| Race/ethnicity, n (%) | Non-Hispanic white | 249 (77) | 64 (79) | 163 (77) | 22 (69) | 0.31 | 63 (74) | 62 (78) | 0.97 |
| Non-Hispanic black | 17 (5) | 5 (6) | 12 (6) | 0 (0) | 5 (6) | 5 (6) | |||
| Hispanic | 37 (11) | 8 (10) | 22 (10) | 7 (22) | 11 (13) | 8 (10) | |||
| Other | 21 (6) | 3 (4) | 15 (7) | 3 (9) | 6 (7) | 5 (6) | |||
| Current smoker, n (%) | No | 290 (89) | 67 (83) | 195 (92) | 28 (88) | 0.09 | 69 (80) | 71 (89) | 0.01 |
| Yes | 36 (11) | 14 (17) | 18 (8) | 4 (13) | 17 (20) | 9 (11) | |||
| Followed a vigorous exercise program in the last 12 mos, n (%) | No | 193 (59) | 46 (57) | 132 (62) | 15 (47) | 0.24 | 59 (69) | 43 (54) | 0.05 |
| Yes | 133 (41) | 35 (43) | 81 (38) | 17 (53) | 27 (31) | 37 (46) | |||
| Education, n (%) | <High school/equivalent | 18 (6) | 3 (4) | 12 (6) | 3 (9) | 0.80 | 7 (8) | 2 (3) | 0.23 |
| Some college or technical school | 67 (21) | 18 (22) | 42 (20) | 7 (22) | 22 (26) | 14 (18) | |||
| College graduate or higher | 238 (74) | 59 (73) | 157 (74) | 22 (69) | 56 (66) | 63 (80) | |||
| Household income, n (%) | <$29 999 | 16 (5) | 4 (5) | 7 (3) | 5 (16) | 0.14 | 4 (5) | 4 (5) | 0.96 |
| $30 000 - $49 999 | 41 (13) | 8 (10) | 29 (14) | 4 (13) | 14 (17) | 9 (12) | |||
| $50 000 - $69 999 | 46 (14) | 11 (14) | 30 (14) | 5 (16) | 12 (14) | 9 (12) | |||
| ≥$70 000 | 215 (68) | 56 (69) | 141 (66) | 18 (56) | 53 (64) | 55 (71) | |||
| Number of previous live births, n (%) | 0 | 170 (52) | 37 (46) | 112 (53) | 21 (66) | 0.42 | 49 (57) | 38 (48) | 0.18 |
| 1 | 106 (33) | 31 (38) | 68 (32) | 7 (22) | 20 (23) | 29 (36) | |||
| ≥2 | 50 (15) | 13 (16) | 33 (15) | 4 (13) | 17 (20) | 13 (16) | |||
| Self-reported menstrual regularity, n (%) | Regular | 276 (85) | 72 (89) | 185 (87) | 19 (59) | 0.0009 | 71 (83) | 68 (85) | 0.31 |
| Not regular | 23 (7) | 4 (5) | 12 (6) | 7 (22) | 9 (10) | 4 (5) | |||
| Varies | 27 (8) | 5 (6) | 16 (8) | 6 (19) | 6 (7) | 8 (10) | |||
| Health insurance, n (%) | Yes | 296 (91) | 74 (91) | 195 (92) | 27 (84) | 0.33 | 74 (87) | 75 (94) | 0.42 |
| No | 28 (9) | 6 (7) | 17 (8) | 5 (16) | 11 (13) | 5 (6) | |||
| Multivitamin use more than once per week in past 3 mos, n (%) | Yes | 209 (65) | 54 (67) | 131 (62) | 24 (75) | 0.28 | 47 (55) | 57 (71) | 0.18 |
| No | 115 (35) | 26 (32) | 81 (38) | 8 (25) | 38 (45) | 23 (29) | |||
| Supplement use more than once per week in past 3 mos, n (%) | Yes | 123 (38) | 33 (41) | 80 (38) | 10 (31) | 0.64 | 29 (34) | 32 (40) | 0.84 |
| Total lipids, mg/dL (mean ± SD) | 628 ± 132 | 617 ± 128 | 626 ± 127 | 672 ± 172 | 0.13 | 639 ± 138 | 612 ± 129 | 0.6 | |
| Urinary creatinine, mg/dL (mean ± SD) | 93 ± 72 | 93 ± 71 | 94 ± 75 | 88 ± 55 | 0.92 | 67 ± 55 | 118 ± 78 | <0.0001 | |
| Age at menarche, y (mean ± SD) | 13 ± 2 | 13 ± 2 | 13 ± 2 | 13 ± 2 | 0.96 | 13 ± 2 | 12 ± 2 | 0.45 |
Values are means ± SDs or n (%), where noted. P values were derived by ANOVA and Fisher’s exact test comparing characteristics by cycle length. Abbreviations: BMI, body mass index; mos, months; SD, standard deviation.