Daily low-dose aspirin beginning as early as the second trimester of pregnancy may prevent complications from preeclampsia, according to an article being published in Annals of Internal Medicine.

Preeclampsia is a condition characterized by high blood pressure and proteinuria during the second half of pregnancy.

Poor perinatal health outcomes are associated with preeclampsia, primarily due to increased risk for intrauterine growth restriction (IUGR) or medically initiated preterm delivery.

Preeclampsia is the leading cause of maternal deaths and is responsible for more than one third of serious maternal morbidities and 15 percent of preterm births.

Predicting which patients will develop preeclampsia is not possible but some conditions, such as preeclampsia in a previous pregnancy or chronic illnesses such as diabetes, hypertension, and renal disease put women at high risk.

Prevention is imperative because the only effective treatment for preeclampsia is delivery, which may have serious neonatal harms before 34 weeks of gestation.

Researchers conducted a systematic evidence review to determine the benefits and harms of low-dose aspirin for preventing morbidity and mortality from preeclampsia. They found that when women at high-risk for preeclampsia started taking a daily low-dose aspirin after their first trimester their risk of developing preeclampsia during the pregnancy dropped by 24-percent. In addition, the risk for preterm birth dropped by 14 percent and the risk for IUGR dropped by 20 percent. No harms of daily low-dose aspirin were identified in the literature.

A draft recommendation based on this review is posted here.