The Nationwide Impact of Guidelines for Prophylactic Aspirin Treatment for Preeclampsia.

Abstract

Background: Preeclampsia is a common pregnancy complication associated with maternal and neonatal mortality. Early aspirin treatment lowers the risk of preeclampsia in high-risk pregnancies. However, knowledge of aspirin's effects and possible side effects outside clinical trials is sparse, and the evaluation of maternal and foetal safety regarding aspirin treatment is hindered by the inherent risk of confounding by indication.

Objectives: To study if the introduction of national guidelines recommending aspirin as preeclampsia prophylaxis affects clinical practice in Denmark, measured by aspirin use and investigate if the guideline change was related to the proportion of preeclampsia, preterm delivery, postpartum haemorrhage (PPH), placental abruption or neonatal intracranial haemorrhage.

Methods: All singleton pregnancies (1997-2016) identified in the nationwide Danish registries (gestational age ≥ 10 weeks) were included. The population was divided into persons at high or low risk of preeclampsia, according to the 2012 Danish National Guideline for Prevention and Treatment of Preeclampsia. Aspirin use was estimated based on redeemed prescriptions. The proportion of outcomes was compared using interrupted time series analyses.

Results: Of 1,323,750 pregnant persons, 2.0% (n = 25,826) were considered at high risk of preeclampsia. After the 2012 guideline change, aspirin use in high-risk pregnancies increased from 2.2% to 12.4% in 4 years, a 0.88 (95% confidence interval [CI] 0.83, 0.93) percentage point change for every half year. Severe preeclampsia slightly decreased from 6.0% to 5.2% after the guideline change, with a -0.22 (95% CI -0.43, -0.01) percentage point change for every half year, while preterm delivery rates remained unchanged. PPH increased in high-risk pregnancies. There was no difference in the risks of placental abruption or neonatal intracranial haemorrhage.

Conclusions: After the introduction of preventive aspirin treatment, aspirin use in high-risk pregnancies increased, and severe preeclampsia decreased. However, PPH increased, while rates of preterm delivery, placental abruption and neonatal intracranial haemorrhage remained unchanged.