Canadian doctors are trying to reduce the number of birth defects resulting from women who drink alcohol during pregnancy.

The Society of Obstetricians and Gynecologists of Canada, which is planning new advice for doctors on the issue, says "surprise pregnancies" are common. Women who weren't in the planning mode may have been drinking during pregnancy, which can lead to children with fetal alcohol spectrum disorder.

'We know that some of the information which is being given to patients is downright wrong.'— Dr. Vyta Senikas

FASD refers to a range of disabilities that are seen in people whose mothers drank alcohol while they were pregnant. Problems children face can include learning disabilities, memory loss, short attention spans and difficulty understanding the consequences of actions.

"It is one of the most common birth defects that we see," said Dr. Vyta Senikas, a vice-president of the society in Ottawa. "The key issue with this birth defect is that it is completely preventable."

Doctors know that a "fairly high" percentage of women don't intend to become pregnant, she added.

Benita Maddox of Prince George, B.C., is one of them. For months, Maddox didn't know she was pregnant. She thought she was gaining weight because she had quit smoking.

"After I found out I was pregnant, I stopped [drinking]," Maddox said.

The science is still uncertain on just how much alcohol, or how little, can cause FASD.

"We know that some of the information which is being given to patients is downright wrong," Senikas said of doctors who give the green light to pregnant women who want to have the odd glass of beer, wine or liquor.

The advice needs to consistent from all health-care providers, including obstetricians, family doctors, midwives and nurses, she said.

The society has launched its own research and review of the scientific evidence. It will issue expert guidelines on alcohol and pregnancy next year.