Drug trial shows we’ve learned from tragedies of the past.

On Monday, Amsterdam University Medical Center announced that researchers there were ending a clinical trial after 11 babies in the study died of lung disease. The mothers of the infants had been given the drug sildenafil — which most of us know by the brand name Viagra — while the babies were still in utero.

The hope had been that the treatment would help increase the delivery of nutrients to the unborn infants, all of whom suffered from serious fetal growth restriction — a condition that greatly increases the risk of stillbirth or infant death soon after birth. Unfortunately, not only were no positive effects found from the sildenafil, the evidence suggests the drug may have caused or hastened the 11 infants’ deaths. None of the babies of women in the control group (who received a placebo instead of sildenafil) died of the same lung condition.

It’s hard to read a headline about 11 babies dying in a drug trial without thinking, “How could something this horrible happen today, with all we now know about the dangers drugs can pose to embryos and fetuses? Didn’t we learn anything from the thalidomide tragedy?”

The answer is that we learned a huge amount from the thalidomide tragedy, in which approximately 2,000 babies died and approximately 10,000 infants were born with severe deformities from the late 1950s until the early 1960s. During that time, thalidomide was widely touted as a safe treatment for morning sickness and was widely prescribed and used as such, even though it had never been thoroughly tested on pregnant women. In 1961, the drug was finally recognized as a teratogen (an agent that causes a malformation of an embryo) and pulled from the market.

Thalidomide taught us the crucial — and now seemingly obvious — lesson that the drugs a pregnant woman takes can cross the placenta and harm the embryo or fetus. It led to more careful and thorough drug-testing procedures; better methods for ensuring informed consent of people participating in drug trials; and more transparency from pharmaceutical companies.

In fact, as horrible as it is that 11 babies died in the recent sildenafil trial — and as understandable as it is that our instinct is to react to this news by recoiling from such experiments — the Dutch study demonstrates how responsible and careful researchers have become about testing drugs for pregnant women.

The trial was halted as soon as the potential problem was discovered. What’s more, researchers conducting similar studies in other parts of the world — including Canada — were notified immediately, allowing them to also take the precaution of halting their trials until it can be established if sildenafil really led or contributed to the babies’ deaths or if the difference between the sildenafil babies and the controls was merely a matter of chance.

Equally important, the public was quickly informed, too. As of this writing, a Google news search for “Viagra” pulls up 46 articles about the babies’ deaths.

The Dutch researchers had no reason to anticipate that sildenafil taken during pregnancy would cause high blood pressure in newborns’ lungs. Sildenafil generally does the opposite: it increases blood flow to the lungs, hence its prescription to adults who have pulmonary high blood pressure, to relieve their symptoms and improve lung function.

It’s possible that the Dutch newborns with high blood pressure in their lungs were actually reacting to the termination of their sildenafil treatment — in a way, the drug they’d been receiving regularly in utero was abruptly terminated once they were born. The lead researcher of the Australian and New Zealand trials told CNN that it “is biologically plausible that withdrawal from the drug at birth has led to a rebound effect on the pulmonary vasculature.”

But it’s not as if this was an obvious outcome the Dutch researchers should have foreseen. None of the other sildenafil trials — in Canada, Australia, New Zealand and the U.K. — had shown similar adverse effects.

When would a mother ever consent to exposing her baby to such a study? Probably only when the odds of the baby surviving and thriving without any intervention were painfully low.

Our willingness to let scientists and parents take such calculated risks — while also taking every reasonable precaution to minimize the chance of harm — is a clear demonstration that we’ve not only learned something from past mistakes, but that we’re also intent on moving forward, even if perfect safety can’t be guaranteed.

We will all reap the benefits of the life-saving possibilities that will result.

RICHARD DREW / THE ASSOCIATED PRESS A trial of the use of sildenafil to help in fetal growth restriction was called off after the deaths of 11 babies.