Table 1. Treatment Assignment, Outcome, Baseline Covariates, and Postrandomization Confounders.
| Variable | Adherence (n = 1227)a | Statistical analysis | P value | |
|---|---|---|---|---|
| No (n = 369 [30.1%]) | Yes (n = 858 [69.9%]) | |||
| Treatment: daily low-dose aspirin | 190 (51.5) | 425 (49.5) | χ21 = 0.4 | .53 |
| Outcome: hCG-detected pregnancy | 107 (29.0) | 677 (78.9) | χ21 = 278.6 | <.001 |
| Baseline covariates | ||||
| Non-Hispanic White race | 334 (90.5) | 827 (96.4) | χ21 = 17.5 | <.001 |
| High school educational level | 302 (81.8) | 755 (88.0) | χ21 = 8.2 | .004 |
| Married | 312 (84.6) | 811 (94.5) | χ21 = 33.1 | <.001 |
| Employed | 283 (76.7) | 636 (74.1) | χ21 = 0.9 | .34 |
| Annual income ≥$40 000 | 213 (57.7) | 608 (70.9) | χ21 = 20.1 | <.001 |
| Exercise per week | ||||
| Low | 106 (28.7) | 216 (25.2) | χ22 = 2.3 | .32 |
| Moderate | 140 (37.9) | 360 (42.0) | ||
| High | 123 (33.3) | 282 (32.9) | ||
| No. of previous pregnancy losses | ||||
| 1 | 125 (33.9) | 278 (32.4) | χ21 = 0.3 | .61 |
| 2 | 244 (66.1) | 580 (67.6) | ||
| No. of previous live births | ||||
| 0 | 173 (46.9) | 352 (41.0) | χ23 = 6.0 | .11 |
| 1 | 125 (33.9) | 308 (35.9) | ||
| 2 | 68 (18.4) | 179 (20.9) | ||
| 3 | 3 (0.8) | 19 (2.2) | ||
| Alcohol ever consumed in past year | 137 (37.1) | 271 (31.6) | χ21 = 3.6 | .06 |
| Tobacco ever smoked in past year | 71 (19.2) | 81 (9.4) | χ21 = 22.8 | <.001 |
| Age, median (IQR), y | 28.0 (24.6-31.8) | 28.4 (25.5-31.8) | NA | .12 |
| Time attempting pregnancy before randomization, median (IQR), mo | 3.0 (1.0-7.0) | 3.0 (1.0-6.8) | NA | .09 |
| BMI, median (IQR) | 25.2 (21.8-30.3) | 24.4 (21.3-29.3) | NA | .05 |
| hsCRP level, median (IQR), mg/dL | 0.13 (0.06-0.36) | 0.11 (0.05-0.31) | NA | .22 |
| Postrandomization confounders | ||||
| Unusual bleedingb | 67 (18.2) | 166 (19.3) | 0.2 (1) | .63 |
| Nausea and/or vomitingc | 69 (18.7) | 138 (16.1) | 1.3 (1) | .26 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); hCG, human chorionic gonadotropin; hsCRP, high-sensitivity C-reactive protein; NA, not applicable.
SI conversion factor: To convert hsCRP to mg/L, multiply by 10.
a
Adherence was measured as taking 5 of 7 pills (70%) per week for 80% of person-weeks of follow-up. Unless otherwise indicated, data are expressed as number (%) of patients.
b
Indicates bleeding ≥1 of 7 days (20%) per week for ≥50% of person-weeks of follow-up.
c
Indicates nausea and/or vomiting ≥1 of 7 days (20%) per week for ≥20% of person-weeks of follow-up.