The spectre of thalidomide still haunted expectant mothers and their doctors when a new hazard to the unborn appeared on the scene.

It was 1985, and while the fetus-deforming morning sickness drug had long been purged from the obstetrics system, an anti-acne agent known as Accutane had stepped in to rekindle its menace.

“It was very clear that levels of anxiety among women and their health-care providers ... were huge,” said Dr. Gideon Koren, a toxicologist at Toronto’s Hospital for Sick Children.

“Accutane caused terrible birth defects, even more than thalidomide.”

It was within this incubating anxiety over safe drug use during pregnancy that Koren hatched an enduring idea.

Twenty-five years later, the hospital’s Motherisk program has helped ease the minds of half a million expectant and new mothers, and become a model for similar efforts around the world.

Initially, the program employed one person, answering a phone and dispensing advice on the dangers of any drug or compound a mother was considering to her fetus or breastfeeding baby.

“Now we have about 70 people working on the different aspects of exposure during pregnancy and during breastfeeding,” Koren said.

The program has also taken to the Internet, where it has become a trusted source in a sea of often contradictory data on drugs and their developmental dangers.

It also dispenses advice on dangers posed by chemicals, diseases, radiation and other environmental agents.