Taking aspirin during the first three months of pregnancy does not appear to improve uterine blood flow
In general, the origin of preeclampsia - particularly preeclampsia manifesting before 34 weeks - is attributed to placental dysfunction, identified by a decrease in uterine artery flow. Doppler ultrasound evaluation of the uterine arteries in the first three months of pregnancy may be useful for detecting possible implantation and placental functional defects that can constitute risk factors for the development of preeclampsia.
On the other hand, there is scientific evidence that aspirin could reduce the risk of preeclampsia in patients identified as being at risk in the first three months. In view of the above, a research group from BCNatal, in collaboration with the Obstetrics Service of Women’s Health Dexeus and Lozano Blesa Clinic Hospital, have carried out a study to determine whether a low dose of aspirin during the first three months of pregnancy can contribute to improve uterine artery flow in women with placental implantation alterations, and thus favour adequate function.
A total of 155 pregnant women with single foetuses presenting such alterations were included in the study. One half of the patients received 150 mg of aspirin a day, while the other half received a placebo tablet. The women were monitored on a monthly basis up until week 28 of pregnancy, with the evaluation of different variables (foetal growth, blood pressure, maternal weight gain, urine tests, etc.). Administration of the drug was not found to significantly improve uterine arterial flow. Only 7 women developed preeclampsia (4 were administered aspirin and 3 placebo). Thus, in view of the low incidence, it could not be demonstrated that aspirin reduces the risk of preeclampsia, though there appeared to be a positive trend in this respect.
In any case, the authors consider that the results of the study do not contradict those obtained by other investigators, and likewise do not indicate that aspirin is unable to exert beneficial effects in terms of the prevention of preeclampsia, since the drug could act via alternative pathways.
Impact of aspirin on trophoblastic invasion in women with abnormal uterine artery Doppler at 11 - 14 weeks: A randomized controlled study (ASAP).
Scazzocchio E, Oros D, Diaz D, Ramirez JC, Ricart M, Meler E, González de Agüero R, Gratacos E, Figueras F.
Ultrasound Obstet Gynecol. 2016 Nov 3. doi: 10.1002/uog.17351.