New study reveals certain prescription drugs can be harmful to fetus

Nov 18 2009

More than six percent of expectant mothers in Quebec consume prescription drugs that are known to be harmful to their fetuses, according to a Universit- de Montr-al investigation published in the British Journal of Obstetrics and Gynaecology. Half these women will voluntarily terminate their pregnancy fearing congenital malformations, which means the abortion rate among these women is 11 percent higher than in the rest of the population.

"I never expected such results and I was extremely surprised," says senior author Anick B-rard, a professor at the Universit- de Montr-al's Faculty of Pharmacy and director of the Research Unit on Medications and Pregnancy of the Sainte-Justine University Hospital Center.

Dr. B-rard examined data from the Quebec Pregnancy Registry on 109,344 women, aged 15 to 45, who were pregnant between 1998 and 2002. Her research team found that 6,871 pregnant women consumed one of 11 prescription drugs that are known to be harmful to fetuses through the first, second or third trimester. Of those women, 3,229 aborted; 6 percent had a miscarriage; and 8.2 percent gave birth to a child with major congenital malformations.

By comparison, the rate of fetal malformations in the general population in the province of Quebec is approximately seven percent. "If there are 80,000 births in Quebec per year, a one percent difference translates into an additional 800 children born with serious malformations," says B-rard, who is currently a visiting professor at the Universit- Claude Bernard in Lyon, France. "At the very best, those babies will die. In the worst case, they'll live with serious physical or psychological health problems their entire lives."

The study also examined the use of prescription drugs that are known to be feto-toxic or increase in-utero problems or premature births. The researchers found that 11,400 prescriptions - for dangerous medicines such as isotretinoin (for the treatment of acne and rosacea), anxiolytic benzodiazepines (anti-anxiety treatment) and antiepileptics (epileptic seizure treatment) - were used by pregnant women. Other drugs that were harmful to fetuses - for hypertension, anticoagulation and infection - were also widely used.

B-rard was shocked to discover that one particular acne treatment is still available on the market in Canada without proper risk management programs, since the product increases the risk of malformations by 30 percent (baseline risk is estimated at 3 percent). Of the 73 pregnant women who used isotretinoin in Quebec, she found, 78 percent got an abortion.

Dr. B-rard believes some drugs are overused, such as benzodiazepine to treat symptoms of anxiety, and should be avoided to reduce the odds of fetal malformations.

Other drugs are necessary however, such as antiepileptics. "In those cases, the pregnancy must be carefully planned and medication use must be at a strict minimum during the first trimester," she stresses. "And the expectant mother must meet with her physician regularly."