Table 1.
Cohort characteristics. Values are mean (SD), median (min-max) or n (%)
| Characteristic | Total Cohort (n = 818) | < 29 years old | p-value* | ≥ 29 years old | p-value* | |||
|---|---|---|---|---|---|---|---|---|
| Non-COC user (n = 164) |
COC user (n = 173) |
Non-COC user (n = 280) |
COC user (n = 201) |
|||||
| Time to Pregnancy, months, median (min-max) | 3 (0–84) | 2 (0–48) | 3 (0–36) | 0.008 | 2 (0–84) | 4 (0–84) | < 0.001 | |
| Age, yr, mean (SD) | 29 (4.5) | 25 (2.4) | 25.5 (2.6) | 0.03 | 32.9 (3.0) | 31.7 (2.4) | < 0.001 | |
| Pre-pregnancy combined oral contraceptive use, n (%) | 374 (45.7) | – | 173 | – | 201 | – | ||
| Parity, median (min-max) | 0 (0–5) | 0 (0–3) | 0 (0–2) | < 0.001 | 1 (0–5) | 0 (0–5) | < 0.001 | |
| Maternal BMI, kg/m2, median (min-max) | 23.7 (16.9–45.4) | 23.8 (17.3–40.1) | 23.3 (17.2–39.3) | 0.25 | 24.1 (16.9–45.4) | 23.7 (18.3–39.8) | 0.83 | |
| Paternal BMI, kg/m2, median (min-max) | 25.6 (18.7–44.0) | 25.4 (19.4–44.0) | 25.5 (18.7–40.4) | 0.98 | 25.7 (19.4–39.9) | 25.8 (19.6–35.9) | 0.96 | |
| Regularity of menses, n (%) | Regular | 695 (85.0) | 131 (79.9) | 152 (87.9) | 0.06 | 250 (89.3) | 162 (80.6) | 0.01 |
| Irregular | 123 (15.0) | 33 (20.1) | 21 (12.1) | 30 (10.7) | 39 (19.4) | |||
| Smoking, n (%) | Non smoker (Cotinine 0–0.2 ng/mL) | 739 (90.3) | 143 (87.2) | 159 (91.9) | 0.33 | 250 (89.3) | 187 (93) | 0.37 |
| Passive smoker (Cotinine 0.2–15 ng/mL) | 38 (4.6) | 9 (5.5) | 7 (4) | 15 (5.4) | 7 (3.5) | |||
| Active smoker (Cotinine > 15 ng/mL) | 41 (5.0) | 12 (7.3) | 7 (4) | 15 (5.4) | 7 (3.5) | |||
| Alcohol, n (%) | Never | 84 (10.3) | 28 (17.1) | 14 (8.1) | 0.07 | 30 (10.7) | 12 (6) | 0.26 |
| Seldom | 359 (43.9) | 80 (48.8) | 93 (53.8) | 102 (36.4) | 84 (41.8) | |||
| Once every other week | 181 (22.1) | 29 (17.7) | 40 (23.1) | 67 (23.9) | 45 (22.4) | |||
| At least once a week | 194 (23.7) | 27 (16.5) | 26 (15) | 81 (28.9) | 60 (29.9) | |||
| Physical activity, n (%) | < 1 h/week | 222 (27.1) | 47 (28.7) | 38 (22) | 0.39 | 90 (32.1) | 47 (23.4) | 0.004 |
| 1 h/week | 133 (16.3) | 27 (16.5) | 28 (16.2) | 54 (19.3) | 24 (11.9) | |||
| 1–2 h/week | 220 (26.9) | 41 (25) | 42 (24.3) | 74 (26.4) | 63 (31.3) | |||
| at least 3 h/week | 243 (29.7) | 49 (29.9) | 65 (37.6) | 62 (22.1) | 67 (33.3) | |||
| Education, n (%) | Elementary | 11 (1.3) | 5 (3.0) | 1 (0.6) | 0.20 | 3 (1.1) | 2 (1.0) | 0.99 |
| High school/vocational | 308 (37.7) | 82 (50.0) | 84 (48.6) | 83 (29.6) | 59 (29.4) | |||
| University/College | 499 (61.0) | 77 (47.0) | 88 (50.9) | 194 (69.3) | 140 (69.7) | |||
Abbreviation: BMI body mass index, COC combined oral contraceptive
*Based on Wilcox, t.test or Chi-square test