A University of Liverpool led international clinical trial has found an anti-impotence drug to be ineffective at improving outcomes for pregnancies complicated by foetal growth restriction.

Foetal growth restriction, commonly called intrauterine growth restriction (IUGR), occurs when the placenta has failed to develop correctly. In most cases this has happened in the early stages of pregnancy but is usually only recognised when the baby is found to be small on ultrasound after twenty weeks. More severe IUGR occurs earlier in pregnancy which has implications as there is currently no treatment for IUGR. Survival for IUGR babies depends on the birthweight and the number of weeks they are at birth. Therefore, a medication that can improve weight or prolong the time to deliver could have significant advantages for these very sick babies.

Sildenafil, commonly called viagra, causes blood vessels to relax and has been used for many years for the treatment of male erectile problems. The University of Liverpool reports researchers at its Institute of Translational Medicine set up the STRIDER Trial to examine whether sildenafil could also cause the blood vessels supplying the placenta to relax and improve the blood supply to the placenta in IUGR pregnancies. Improving the blood supply to the placenta should improve the growth and wellbeing of the IUGR baby.

As part of the study researchers recruited one hundred and thirty five women from nineteen foetal medicine units in the UK who were less than thirty weeks into their pregnancies with an IUGR baby. Randomly seventy of the women were prescribed sildenafil and sixty five women a placebo.

The results of the trial, which have been published in The Lancet Child & Adolescent Health, found that when sildenafil was administered to pregnant women with a severely growth restricted foetus, it did not prolong pregnancy, improve survival, or reduce short term neonatal morbidity.

Professor Zarko Alfirevic, said “Sadly the use of this drug in this way was ineffective. However, as part of our continuing research, we are now monitoring the growth and development of the babies who participated in the trial to learn even more about this disease and its implications with a view to help us to identify possible treatment options in the future.”

The study was funded by the National Institute for Health Research and Medical Research Council.