Table II.
Baseline and menstrual cycle characteristics of the BioCycle participants, by smoking status.
| Smoking Status | |||
|---|---|---|---|
| CHARACTERISTIC | Smokers (n=16) |
Nonsmokers (n=243) |
P-value a |
| DEMOGRAPHIC | |||
| Age (years) | 0.84 | ||
| <20 | 1 (6.3) | 38 (15.6) | |
| 20–29 | 10 (62.5) | 126 (51.9) | |
| 30–39 | 3 (18.8) | 48 (19.8) | |
| ≥40 | 2 (12.5) | 31 (12.8) | |
| Race | 0.09 | ||
| White | 13 (81.3) | 141 (58.0) | |
| African American | 0 (0) | 51 (21.0) | |
| Other | 3 (18.8) | 51 (21.0) | |
| BMI category (kg/m2) | 0.66 | ||
| <18.5 | 1 (6.3) | 8 (3.3) | |
| 18.5 to <25 | 10 (62.5) | 148 (60.9) | |
| 25 to <30 | 3 (18.8) | 63 (25.9) | |
| ≥30 | 2 (12.5) | 24 (9.9) | |
| LIFESTYLE | |||
| Physical activity (Total MET- min./week) |
7452.4 ± 7215.3 | 5498.5 ± 6967.5 | 0.21 |
| Vigorous physical activity (Vigorous MET-min./week) | 1808.0 ± 3044.3 | 1626.1 ± 3158.2 | 0.68 |
| Caffeine (mg/day) intake | 179.1 ± 191.0 | 108.3 ± 139.5 | 0.20 |
| Alcohol (mg/day) intake | 5.7 ± 5.6 | 4.5 ± 8.1 | 0.07 |
| REPRODUCTIVE | |||
| Age at first menstrual period (years) | 12.1 ± 1.3 | 12.5 ± 1.2 | 0.22 |
| Nulliparity | 11 (78.6) | 176 (73.6) | |
| MENSTRUAL CYCLE (n=509b) | |||
| Luteal phase length in observed cycles | 12.9 ± 2.6 | 12.9 ± 2.8 | 0.46 |
| Follicular phase length in observed cycles | 16.1 ± 3.9 | 16.9 ± 5.4 | 0.96 |
| Anovulatory cycles | 41 (8.6) | 1 (3.2) | 0.50 |
| Cycles shifted by re-centering algorithm | 310 (64.8) | 18 (58.1) | 0.44 |
Notes: table values are mean ± SD for continuous variables and n (%) for categorical variables. Percentages may not sum to 100% due to rounding. Numbers may not sum to full sample size due to incomplete covariate information.
a
P-values from Wilcoxon rank sum test, χ2 test, or Fisher’s exact test as appropriate
b
Among 509 cycles observed, 31 were from smokers, 478 from nonsmokers