http://www.sciencemag.org/news/2018/07/trials-viagra-help-poorly-growing-fetuses-are-halted-after-infant-deaths

AMSTERDAM—When gynecologist Wessel Ganzevoort received a request for an urgent meeting from the independent committee watching over his clinical trial last week, he thought it might be good news.

Ganzevoort leads a study to find out whether sildenafil, sold under the brand name Viagra, could help poorly growing fetuses if given to their pregnant mothers; the drug dilates blood vessels and in theory could bring fetuses more oxygen and nutrients. A data and safety monitoring committee, however, had looked at the unblinded evidence halfway through the study and wanted to talk. Ganzevoort, who’s at the Amsterdam University Medical Center (AUMC), knew that probably meant one of two things: Either the drug worked so well that continuing to give a placebo to half of the mothers in the trial would be unethical, or the study had to be stopped because sildenafil was causing serious complications. Because previous studies had not shown any major side effects, Ganzevoort expected the former.