| Variable | Sildenafil plus low-dose aspirin (n = 200) | Low-dose aspirin only (n = 200) | P-value* | |||
| n | % | n | % | |||
| Risk factor for PE | Age ≥ 35 years | 39 | 19.5% | 40 | 20.0% | 0.900 |
| BMI ≥ 30 kg/m2 | 39 | 19.5% | 40 | 20.0% | 0.900 | |
| Primigravida | 29 | 14.5% | 39 | 19.5% | 0.183 | |
| Past history of PE | 49 | 24.5% | 53 | 26.5% | 0.646 | |
| Family history of PE | 26 | 13.0% | 18 | 9.0% | 0.201 | |
| Multifetal gestation | 35 | 17.5% | 26 | 13.0% | 0.211 | |
| Chronic hypertension | 36 | 18.0% | 33 | 16.5% | 0.691 | |
| DM type 1 or 2 | 23 | 11.5% | 33 | 16.5% | 0.150 | |
| CKD | 28 | 14.0% | 24 | 12.0% | 0.552 | |
| Autoimmune disease | 28 | 14.0% | 27 | 13.5% | 0.885 | |
| Sociodemographic risk factors | 200 | 100.0% | 200 | 100.0% | NA | |
| LBW, SGA or >10 years IPI | 26 | 13.0% | 29 | 14.5% | 0.663 | |
| Number of risk factors | 2 RF | 103 | 51.5% | 99 | 49.5% | 0.950 |
| 3 RF | 71 | 35.5% | 75 | 37.5% | ||
| 4 RF | 17 | 8.5% | 21 | 10.5% | ||
| 5 RF | 9 | 4.5% | 4 | 2.0% | ||
| 6 RF | 0 | 0.0% | 1 | 0.5% | ||