Impact of early supplementation with low-dose aspirin on functional first trimester parameters in low-risk pregnancies

Introduction: There is recent evidence that prophylaxis with 150 mg of aspirin given before 14-16 weeks significantly reduces preeclampsia rates and may improve pregnancy outcome. We conducted an observational study that investigates the effect of low-dose aspirin initiated early in pregnancy or in preconception on functional parameters assessed at 11-14 weeks. Materials and methods: We have retrospectively selected 128 pregnant women that presented for the first trimester screening for aneuploidies between 11(+0) and 13(+6) weeks of gestation and received low-dose aspirin before 14 weeks. We excluded cases with an estimated high risk for early preeclampsia (cut-off > 1:100). This group was matched to 1044 cases that did not receive aspirin in early pregnancy. We have selected for statistical analysis maternal parameters, ultrasound parameters (crown-rump length, nuchal translucency thickness, pulsatility index in uterine arteries - left, right, average and average uterine PI expressed in multiple of median (MoM)), first trimester maternal biochemical markers (free beta hCG and PAPP-A expressed in MoM), and the calculated risk for early onset and late onset preeclampsia. Results: The most common dosages of aspirin were 75 mg (77 cases) and 100 mg (32 cases). The most significant results are within the aspirin group. In the subgroup that received aspirin before 11 weeks (110 cases), irrespective of the dosage, the uterine blood flow is significantly improved (average uterine PI 1.7 compared with 2.22, p < .05, (0.24-0.7) 95% CI) and the PAPP-A levels are higher (1.2 compared with 0.82, p > .05, [(-0.65) - 0.02] 95% CI). The estimated risk for both early and late onset preeclampsia in this group is reduced (1:2141 compared with 1:333 for early preeclampsia, p < .05, (1216-2398) 95% CI; 1:361 compared with 1:99 for late onset preeclampsia, p < .05, (173-351) 95% CI). Conclusion: Even though the results are not always statistically significant, they demonstrate that placentation parameters improve with higher doses of aspirin started before 11 weeks.