Scientists urge caution on using viagra for foetal therapy

Scientists in Manchester have urged caution for those using Viagra, due to fears the drug could increase blood pressure in babies.

A team from the University of Manchester has been testing out the drug as a possible treatment for foetal growth restriction (FGR) – a condition in which babies grow poorly in the womb.

FGR is estimated to affect three in every 100 pregnancies, with most cases being caused by a poorly functioning placenta, which can affect blood flow and the transfer of nutrients to the baby.

Babies with FGR are at increased risk of stillbirth and are more likely to suffer from developmental problems and other conditions such as heart disease and diabetes in adulthood. No treatments are available for FGR and often the only option for obstetricians is to deliver the baby early so they can be cared for outside the womb.

 Viagra has been undergoing trials to treat FGR, as it’s thought that since it enhances blood flow, it could improve conditions in the womb. However, a recent study in mice suggested that Viagra showed no improvement in foetal growth and instead resulted in high blood pressure in pups as they reached maturity.

The Manchester team are the first to report on the long-term effects of the drug with their results in the American Journal of Physiology – Heart of Circulatory Physiology.

The Manchester study showed that over 90% of mice whose mothers were given Viagra during their pregnancy experienced a significant increase in blood pressure. The increase was high enough to be equivalent to values used to diagnose high blood pressure in humans.

Another international study on the effects of Viagra for those with FGR also found that the drug had no significant benefit on foetal growth or prolongation of pregnancy. The Dutch arm of the international study - called STRIDER – was also halted after 11 babies of mothers using the medication died from lung complications.

The study was carried out by former PhD student Dr Lewis Renshall. He said: “This, and other studies have shown Sildenafil – otherwise known as Viagra – may not be a suitable treatment for FGR unless life-saving benefits can be demonstrated.”

 “So there is still much work to do if we are to eventually find a treatment for this distressing condition.”

Dr Mark Dilworth, who led the study, added: “The evidence from this study and others suggest that caution should be used for the use of Viagra in foetal Growth Restriction. Our study suggests there may be long-term risks associated with its use in mice and importantly, there is a lack of beneficial effect in recent human clinical trials.”

“We do feel, however, that it is important to continue to conduct studies which look at longer term impacts of giving medication during pregnancy as there is surprisingly little research on this.”