As results from a major New Zealand-Australian clinical trial are revealed, the jury’s out on whether sildenafil – also known as Viagra - taken by mothers during pregnancy could help babies suffering from stunted growth in the womb by increasing blood supply to the placenta.
Results from STRIDER NZAus will be presented by chief investigator Associate Professor Katie Groom, Hugo Charitable Trust Clinical Research Fellow at the University of Auckland-based Liggins Institute, at a conference on mother and baby health research on Tuesday, and a public lecture on Wednesday evening.
Fetal growth restriction, also called intrauterine growth restriction, is when a baby cannot grow properly due to problems with the placenta. It affects 5-10 percent of babies, or 25 million per annum globally (3,000-6,000 in New Zealand), and can lead to stillbirth or to babies being born very small and at high risk of disabilities, developmental problems, short-term and later illness. Currently there is no treatment except early delivery, which can exacerbate those potential long-term problems.
The STRIDER NZAus trial involved 122 women recruited in Christchurch, Wellington, Auckland and six Australian cities. Half took sildenafil, half took a placebo. The women and babies were closely monitored until surviving babies left neonatal units.
The researchers found no effect on growth in the womb, but did detect a trend towards higher survival of the babies in the sildenafil group before and after birth: 81 percent, or 51 out of 63 babies compared to 73 percent, or 43 out of 59 babies, in the control group. They also found that 11 percent more babies in the sildenafil group survived free of major illness before leaving hospital, and fewer new cases of a serious pregnancy complication called preeclampsia in mothers after starting treatment (14 percent versus 23 percent).
Dr Groom: “Because of the small size of the study these differences are not statistically significant - this may mean this is simply a chance finding. However, if we saw the same differences in a larger group of mother and babies, this would be a very important difference, really having the potential to change lives in the future.”
The opportunity to explore the effect of this drug in a larger group is already underway. STRIDER NZAus is part of an international network of four trials across five countries. The STRIDER UK trial, led by the University of Liverpool, published its findings late 2017. It found that when sildenafil was given to pregnant women with severely growth-restricted babies, it did not prolong pregnancy, improve survival, or reduce short-term illness in the babies after birth.