Pregnant women with a history of depression who used psychiatric medication have triple the risk of premature child delivery, U.S. researchers found.

Researchers at the University of Washington, University of Michigan and Michigan State University found that a combination of medication use and depression -- either before or during pregnancy was strongly linked to delivery before 35 weeks' gestation.

Lead author Amelia Gavin of the University of Washington said the findings highlight the need for carefully planned studies that can clarify associations between depression, psychiatric medications and preterm delivery.

"Women with depression face difficult decisions regarding the benefits and risks of using psychotropic medications in pregnancy," Gavin said in a statement.

"Therefore, a focus on disentangling medication effects and depression effects on mother and offspring health should be a major clinical priority."

The study examined the associations among maternal depression, psychiatric medication use in pregnancy and preterm delivery among women in five Michigan communities who received prenatal care at one of 52 participating clinics between September 1998 and June 2004. To be included in the study, the women had to be at least age 15 with no history of diabetes and were 15-27 weeks pregnant.