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Anticoagulant does not increase live birth rate in patients with inherited blood clotting and recurrent miscarriage

A medication commonly prescribed pregnant patients with an inheritable blood clotting condition and a history of recurrent miscarriage does not help to reduce their miscarriage risk, a new international study led by UK researchers and funded by the NIHR has found.

Researchers are advising doctors to stop offering the anticoagulant Low Molecular Weight Heparin (heparin) to patients with inherited thrombophilia – a condition where the blood has an increased tendency to form clots in veins and arteries.

Despite the lack of evidence and guidance, doctors often prescribe heparin to patients with recurrent miscarriage and inherited thrombophilia. It’s costly for health services, and inconvenient because    the drug must be injected daily and is therefore likely to cause bruising.

Stopping screening for inherited thrombophilia and ending the use of heparin as a treatment for these patients could save the NHS around £20m per year, researchers say, with funding diverted to other services or treatments.

A new study funded by the National Institute for Health and Care Research (NIHR) and published in The Lancet on Tuesday 30 May shows that a daily injection of heparin does not improve the chance of a live birth for patients who have previously had 2 or more miscarriages and confirmed inherited thrombophilia, when compared to standard care.

Led by Professor Siobhan Quenby, Professor of Obstetrics at the University of Warwick and Deputy Director of the Tommy’s National Centre for Miscarriage Research the ALIFE2 trial recruited people from 40 hospitals in the UK, Netherlands, USA, Belgium and Slovenia.

326 patients with inherited thrombophilia and recurrent miscarriage were split into 2 groups – 164 received heparin across the course of their pregnancy, starting from as soon as possible after a positive pregnancy test and ending at the start of labour. Some 162 were not offered the medication.

All participants received standard obstetrician-led care and all were encouraged to take folic acid.

The rate of live births for each group was roughly the same: 116 (71.6%) treated with heparin had a baby born alive after 24 weeks’ pregnancy. 112 (70.9%) in the standard care group had a baby born alive after 24 weeks’ pregnancy.

The risk of other pregnancy complications, such as miscarriage, babies with low birth weight, placental abruption, premature birth or pre-eclampsia, was about the same for both groups.

As expected, bruising easily was reported by 73 (45%) of people the group taking heparin (mostly around injection-sites) and only 16 (10%) in the standard care group.

Professor Quenby says: “Based on these findings, we don’t recommend the use of Low Molecular Weight Heparin for patients  with recurrent pregnancy loss and confirmed inherited thrombophilia.

“We also suggest that screening for inherited thrombophilia in patients with recurrent pregnancy loss is not needed. Patients and doctors will always value knowing about any factor which could be associated with recurrent miscarriage, but the association between inherited thrombophilia and recurrent miscarriage isn’t proven: a recent review of research showed that thrombophilia is as common in the general population as it is in patients with recurrent miscarriage.

“Around the world many of those who suffer with recurrent miscarriage are tested for inherited thrombophilia and are treated with heparin daily. Research now shows that this screening is not needed, the treatment isn’t effective, and it is giving false hope to many by continuing to offer it as a potential preventive treatment.”

Of those 28% who participated in the trial, 28% lost their badly wanted pregnancies, and these unexplained losses will be the focus of further study, as our researchers continue to search for answers and treatment to prevent early pregnancy loss.

University of Warwick press office contact:  

Annie Slinn 

Communications Officer | Press & Media Relations | University of WarwickLink opens in a new window  
Email: opens in a new window 


Fri 02 Jun 2023, 11:52 | Tags: medicine, research, WMS