Postpartum venous thromboembolism prophylaxis may cause more harm than benefit: a critical analysis of international guidelines through an evidence‐based lens

Based on prediction models and expert opinion, most obstetric venous thromboembolism guidelines recommend low‐molecular‐weight heparin for many postpartum women, including most delivering by caesarean. Scrutiny reveals major oversights: prediction models are based on studies that report asymptomatic deep vein thrombosis; risk estimates are not adjusted for time exposure; and harm caused by heparin has been overlooked. The benefits of heparin are exaggerated and its harms are under‐appreciated. Estimates of the numbers‐needed‐to‐treat and harm are universally lacking. This paper critically reviews the evidence and quantifies the benefit and harm from low‐molecular‐weight heparin in postpartum women with common risk factors. FUNDING: This work was unsponsored and unfunded. TWEETABLE ABSTRACT: Randomised trials should demonstrate more benefit than harm before widespread postpartum low‐molecular‐weight heparin is recommended.