Prescribers should stop offering heparin to pregnant patients with the blood-clotting condition inherited thrombophilia and a history of recurrent miscarriage after a study showed the anticoagulant does not help reduce their risk of a future miscarriage.

The conclusion was drawn by a research team led by the University of Warwick whose study was funded by the National Institute for Health and Care Research and published in The Lancet. They recruited 326 patients with inherited thrombophilia and recurrent miscarriage from 40 hospitals in the UK, Holland, Belgium, Slovenia and the US and divided them into two groups – 164 were given heparin during their pregnancy and 162 were not.

The rate of live births for both groups was similar - 116 given heparin had a baby born alive after 24 weeks’ pregnancy and 112 not given the drug also had a baby born alive after 24 weeks.

Researchers also found the risk of complications such as miscarriage, babies born with low weight, placental abruption, premature birth or pre-eclampsia, was “about the same for both groups.”

Bruising easily was also reported in 73 of the patients who took heparin but in just 16 who did not. Twenty-eight per cent who participated in the study lost their pregnancies and researchers said those “unexplained losses will be the focus of further study.”

Giving patients heparin via a daily injection is costly but doctors continue to prescribe it despite the lack of evidence as to its effectiveness in patients who have suffered recurrent miscarriage and have inherited thrombophilia.

Ending the use of heparin to treat those patients could save the NHS £20 million a year, the study said.

“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,” said 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 that carried out the study.

She also said 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," she said. 

“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.”