Low-dose aspirin in pregnancy: who? when? how much? and why?

The use of low dose aspirin (LDA) has become routine in prenatal care for a variety of diagnoses, most importantly in women with a history of preeclampsia and associated poor pregnancy outcomes. Although LDA is currently indicated in patients considered to be at risk for development of preeclampsia, optimal dosing, timing of treatment initiation, and persons of benefit are under investigation. Several studies have also looked at LDA treatment and its effect on other maternal and fetal outcomes. This review summarizes the current guidelines for the use of LDA, incorporating the most recent research findings, and offers possible future implications of LDA treatment.

Over 10 years ago, the American College of Obstetricians and Gynecologists, the World Health Organization, and the United States Preventive Service Task Force began publishing guidelines focused on the use of LDA in pregnancy. Since the release of these guidelines, several large studies have re-evaluated the use of LDA with a focus on initiation of treatment and dosing. The combined results of these studies suggest a decreased rate of preeclampsia at aspirin doses >100 mg when treatment is initiated prior to 16 weeks of gestation.

Overall, early initiation of LDA has been shown to decrease the development of preeclampsia in patients considered at increased risk. Current literature suggests increasing the recommended dose to >100 mg to optimize these risk reductions. Although LDA use seems promising for other outcomes like preterm delivery and intrauterine growth restriction, further studies to strengthen recommendations are warranted.