Viagra Clinical Trial of Pregnant Women Ends After 11 Babies Die as a Result of Lung Problems

A Dutch clinical trial investigating the use of Viagra (sildenafil) in pregnant women has been halted following the death of 11 babies. A generic version of the erectile dysfunction drug not manufactured by Pfizer was being tested as a potential way to increase the growth of babies suffering from fetal growth restriction in utero.

Since Viagra works by dilating the blood vessels, the researchers conducting the trial hypothesized that it could improve blood flow through the placenta, thereby improving the growth of the baby. Preclinical data from rats showed that this might work, leading researchers to test the drug in pregnant women.

“We wanted to show that this is an effective way to promote the growth of the baby,” said Wessel Ganzevoort, a gynecologist at the University of Amsterdam and lead researcher on the study. “But the opposite happened. I am shocked. The last thing you want is to harm patients.”

In all, 10 sites in the Netherlands enrolled 93 pregnant women to take sildenafil, all of whom had been diagnosed with underperforming placentas. Without treatment, it was predicted that these poorly-developing babies would have a negative prognosis once born.

Seventeen babies whose mothers participated in the sildenafil trial developed lung problems after birth, 11 of whom succumbed to their breathing issues. This prompted an independent monitoring committee to terminate the trial. Eight other babies died of conditions that were unrelated to sildenafil, leaving up to 10 other mothers who also participated in the trial to worry about what the outcome may be for their own baby.

However, nine women in the placebo arm of the trial also experienced the death of their child from issues unrelated to the study. While three of the babies born to women taking the placebo developed similar lung problems as those seen in the treatment arm, none of these babies died as a result.

The investigators believe that high blood pressure caused by sildenafil may have limited the amount of oxygen babies received. However, since Viagra is currently prescribed to non-pregnant patients diagnosed with high blood pressure, it’s unclear what may have caused this effect in the expectant mothers.

According to Ganzevoort, a similar study was being conducted in Canada but has since been stopped after researchers were informed of the news.

Despite the lack of evidence for using sildenafil to treat fetal growth restriction, Granzevoort said that doctors would sometimes prescribe it to women off-label. Still, a UK-based study published late last year found no evidence that the drug could promote fetal growth, nor did it identify any potential adverse events like those seen in the current trial.

“Foreign colleagues let slip that they sometimes prescribed it, with good results,” said Granzevoort. “I have experienced in my own consulting room that pregnant women asked for it.”