EP08.09: Does Low Dose Aspirin Effect Mean Uterine Artery Doppler Pulsatility Index in Women Deemed High Risk for Early Pre‐eclampsia?

The risk of pre-eclampsia requiring delivery <34 weeks' gestation (ePET) can be predicted at 12 weeks gestation and low dose aspirin is effective in preventing this disease. The precise effect of aspirin remains unclear but treatment may improve trophoblast invasion. We examine the effect of aspirin on the uteroplacental circulation; specifically on mean uterine artery pulsatility index (UtArtPI). A retrospective review of singleton pregnancies screened for ePET at 11+0–13+6 (‘12’) weeks' gestation. Data for the mean UtArtPI at 12 and, where available, 22+0–25+6 (‘24') weeks' gestation were retrieved from the Fetal Medicine Database. An observational and an interventional cohort were identified; each had low and high risk subgroups. The high risk interventional cohort had been advised to take aspirin (150 mg/nocte). MeanMoM UtArtPI Doppler values were calculated and compared to determine significant difference. 201 (160 low risk and 41 high risk for ePET) had Dopplers at both time points. The meanMoM (+IQR) for UtArtPI in the low risk/observational cohort was 0.98 (0.79–1.13) and 0.95 (0.73–1.10) at 12 and 24 weeks respectively. This compared to meanMoM (+IQR) values of 1.38 (1.14–1.60) and 1.18 (0.89–1.42) in the high risk/observational subgroup. 542 (251 low risk and 291 high risk for ePET) women were included. The meanMoM (+IQR) for UtArtPI in the low risk/interventional subgroup was 0.97 (0.77–1.17) and 0.95 (0.73–1.10) at 12 and 24 weeks' respectively. This compared to meanMoM (+IQR) values of 1.47 (1.22–1.66) and 1.24 (0.84–1.26) in the high risk/interventional subgroup who had been advised to take aspirin. Mean UtArtPI meanMoM values were appropriate for gestation in both low risk subgroups. MeanMoM values were higher in both high risk subgroups but showed some reduction toward the expected median with advancing gestation. There was no significant difference between the reduction seen between observational and aspirin treated cohorts.