Best Evidence Topics
  • Send this BET as an Email
  • Make a Comment on this BET

LMWH use in pregnancy does not cause excess bleeding during labour

Three Part Question

In [pregnant women with a suspected PE] does [LMWH] increase the risk of [bleeding/haemorrhage] during labour.

Clinical Scenario

A pregnant lady is diagnosed with a PE in the ED you start her on a LMWH even though you are not entirely convinced she has a PE. You question whether you should withhold anticoagulation treatment in case of the side effects especially in terms of bleeding during labour.

Search Strategy

All EBM Reviews - Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED 2nd Quarter 2008. EMBASE 1996 to 2008 week 25. Medline 1950-Week 2 June 2008 using the OVID interface. CINAHL 1982 to June Week 2 2008.

([{pregnanc$.mp. OR exp Pregnancy OR exp Pregnancy Complications or OR exp Pregnant Women}] AND [exp Pulmonary Embolism OR pulmonary embolu$.mp. OR pulmonary OR exp Venous Thrombosis/ pleuri$.mp. OR pulmonary embol$.mp.]) AND {heparin$.mp. OR exp Heparin, Low-Molecular-Weight} AND {exp Obstetric Labor Complications OR exp Labor, Obstetric OR exp Pregnancy OR labour$.mp. OR Hemorrhage OR haemorrhage$.mp.} LIMIT to human AND english.

Search Outcome

330 papers found. One recent systematic review identified. No relevant papers published after the date (2007) of the systematic review.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Deruelle P et al
Literature review between January 2005 and June 2007 focussing on randomised studies in the use of LMWH in pregnancy. Systematic review.Rate of major bleeding in pregnant patients on LMWH. Around 2%. Reference to 4 papers represented as level 1 evidence. In the search strategy the authors state that 151 papers were identified and that they reviewed the most relevant publications, but fail to mention the inclusion criteria for the review. Review includes quotation of case reports.
Enoxaparin is relatively safe to use during pregnancy.One serious bleeding event out of 624 patients. (Level 1 evidence)
Rate of peripartum bleeding complications.Not increased; one study followed current guidelines on LMWH use in pregnancy. (Level 1 evidence).
Safety protocol for safe LMWH before delivery.Stopping LMWH up to 24 hours is just as safe as stopping 12hours before labour. Commence again post-12 hours birth


The authors’ have produced a strong review on the use of LMWH in pregnancy. Six papers in the review were relevant to this clinical question all of which were level 1 evidence. LMWH despite their high cost have great benefit for the prophylaxis of DVT/PE in pregnancy.

Clinical Bottom Line

LMWH does not cause excessive bleeding at labour.


  1. Deruelle P, Coulon C The use of low-molecular-weight heparins in pregnancy--how safe are they? Curr Opin Obstet Gynecol. 2007 Dec;19(6):573-7.47