The mothers were part of a clinical trial to evaluate the safety and effectiveness of the drug on unborn babies who had severe fetal growth restriction.

They also faced significant risk of being stillborn or dying after birth, according to a study that detailed the design and protocol of the clinical trial.

Placebo treatment

Half of the 183 mothers in the viagra trial had been treated with sildenafil while the other half were treated with a placebo.

At the time they were treated, the mothers did not know which treatment they were receiving, which is standard in clinical trials.

“Fetal growth restriction happens when the growing fetus doesn’t get enough nutrients or oxygen from the placenta,” said neonatologist Dr. Mohan Pammi.

High blood pressure

It sometimes occurs because the mother has high blood pressure, uncontrolled diabetes or a condition called preeclampsia, he added.

And babies born too small can experience a host of problems, including smaller head sizes, lack of blood flow to the intestines and death.

The hope was that the drug “can open up some blood vessels in the placenta and then can help the growth of the fetus,” Pammi said.