ABSTRACT

Background Pre-eclampsia is a condition that affects approximately 3-7% of pregnant women annually and is the most common cause of perinatal and maternal morbidity and mortality. For a long time, pre-eclampsia has been called "the disease of theories" because the etiology of the condition is not fully understood. More recent studies explain pre-eclampsia as a condition consisting of two stages. In the first stage, impaired trophoblast invasion occurs through the decidualized endometrium resulting in incomplete remodelling of the spiral artery which in turn leads to constricted vessels and placental ischaemia. Placental ischaemia causes, in the second stage, the release of immune cells, cytokines and anti-angiogenesis markers which in turn leads to the maternal endothelial dysfunction that occurs in pre-eclampsia.  

Pre-eclampsia is divided into different classes depending on the week of pregnancy in which it develops. The subgroups are referred to as early, premature and term pre-eclampsia. Women who suffer from pre-eclampsia during pregnancy tend to develop cardiovascular diseases later in life and the baby born is at risk of developing chronic diseases. 

Necessary symptoms for diagnosis of the disease are hypertension in normotensive women and/or proteinuria. In addition, the woman may suffer from renal insufficiency or hepatic insufficiency. Some of the risk factors that can lead to pre-eclampsia are chronic hypertension, multiple gestation and high maternal BMI. 

The American College of Obstetricians and Gynecologists (ACOG) recommends acetylsalicylic acid for women who are at moderate to high risk of developing pre-eclampsia. Acetylsalicylic acid has several effects including inhibition of platelet aggregation via irreversible inhibition of cyclooxygenase (COX) acting on endothelial function. 

Aim The study was performed to analyze whether pregnant women with moderate and high risk for pre-eclampsia routinely receive a prophylactic effect of low-dose acetylsalicylic acid and to investigate whether it can reduce the incidence of preterm delivery.  

Methods and materials Relevant scientific clinical randomised trials were searched using the Pubmed medical database and search engine. Five studies between 2012-2022 were reviewed and selected.

 Results The aspirin doses used in studies 1-4 ranged from 100-160 mg and were administered daily. The studies did not show any statistically significant difference on pre-eclampsia development between the group administered aspirin or placebo. Study 5, on the other hand, analysed whether aspirin had any effect on reducing the incidence of, among other things, preterm labour (<37 weeks of gestation). The results of study 5 showed that preterm labour occurred in 11.6% of women treated with aspirin compared with 13.1% of cases in the placebo group, which was statistically significant.

Discussion ACOG guidelines as well as the international recommendations seem to base their evidence on insufficient older studies. The studies that have been analysed show no prophylactic effect of aspirin. Although there were fewer pre-eclampsia cases in the aspirin groups compared to the placebo groups, the difference was not significant. However, the results of study 5 may be unreliable because the study was conducted in low- to middle-income countries where there is a higher risk of preterm birth and that a minimal treatment may play a major role. Therefore, several larger international studies conducted on relevant aspects are needed to demonstrate the effect of aspirin on pre-eclampsia.