Preeclampsia, a serious complication of pregnancy that causes high blood pressure and excess protein in urine, affects about five percent of pregnancies and is the leading cause of maternal death among all pregnancy-related conditions associated with high blood pressure.
It can develop in one out of every twenty pregnancies in healthy mothers, with the risk increasing with older maternal age, multiple pregnancies (twins), previous history of high blood pressure, obesity and/or during a first pregnancy. Aspirin (active ingredient) is a common preventive treatment for preeclampsia, typically in daily doses ranging from 25 to 100 mg.
To find out whether increasing the dose would be more effective, the researchers at Semmelweis university reviewed data from nearly 55,000 pregnant women.
“We wanted to see if there’s any benefit to giving higher doses of aspirin”, says first author Balázs Komoróczy of the Department of Obstetrics and Gynecology, Semmelweis University.
“Our aim was to study the largest population possible and compare different dosage ranges, regardless of known risk factors”, he adds.
In the group that received the 100 mg dose, the most commonly used in practice, the incidence of preeclampsia was reduced by 60%.
However, increasing the dose to 150 mg did not necessarily lead to a greater reduction in risk.
“We could not establish a clear correlation between dosage and efficacy”, the researcher notes.
When deciding on preventive treatment, physicians assess individual risk factors. “Aspirin being a blood thinner, the main concern is an increased risk of bleeding”, says Komoróczy adding that this often discourages routine administration.
While the study did observe slightly higher rates of bleeding among the women involved, the increase did not reach statistical significance. “This suggests the difference may be due to chance”, said Komoróczy.
The timing of aspirin therapy is more important than dosage. For optimal effectiveness, it is advised to start treatment early, ideally between the 12th and 15th weeks of pregnancy.
“Preeclampsia and pregnancy-induced hypertension generally develop around the 20th week in individuals prone to developing this condition”, says corresponding author Nándor Ács, director of the Department of Obstetrics and Gynecology, Semmelweis University. If high blood pressure (≥140/90 mmHg) is measured on multiple occasions earlier than that, it is considered chronic hypertension.
Though preeclampsia is widely researched, most studies focus on specific subgroups. Comparisons between different aspirin doses (rather than versus placebo) are rare. “Future research should further compare higher doses to established effective ones, but current data on this is limited”, Komoróczy notes.
Photo: Semmelweis University – Bálint Barta, Attila Kovács, illustration: iStock
