| Methods |
Randomised |
| Participants |
186 women aged 18 years or older with a singleton pregnancy, crown rump length 45 mm to 84 mm, an abnormal Doppler at 11 to 14 weeks and no other risk factors for PE |
| Interventions |
Aspirin 150 mg extended release vs placebo, until 28 weeks' gestation |
| Outcomes |
Pulsatility index at 28 weeks; PE; early onset PE (delivery before 34 weeks); severe PE; SGA, neonatal metabolic acidosis at birth. |
| Notes |
Conducted at three university hospitals in Spain. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Web‐based randomisation, stratified by site |
| Allocation concealment (selection bias) |
Low risk |
Sites contacted a central office for randomisation, which then sent them the allocation by fax. |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Women, caregivers and investigator described as blind to the allocation. |
| Incomplete outcome data (attrition bias)
All outcomes |
High risk |
31/186 (17%) women excluded from analysis: lost to follow‐up (7 aspirin vs 6 placebo)' voluntary withdrawal (6 vs 5), preterm birth < 28 weeks 1 vs 1), congenital malformation (1 vs 1), miscarriage, (2 vs 0), asthma attack 0 vs 1). |
| Selective reporting (reporting bias) |
Unclear risk |
Protocol not available. Outcome reported for those listed in methods, with some additional outcome data reported that are not in methods. |
| Other bias |
Low risk |
Baseline characteristics balanced between groups (see table 1). |
