"Health professionals want to identify pregnant women who may be at risk for postpartum depression in hopes of initiating preventive strategies," says U of T nursing professor Cindy-Lee Dennis. "But in my review of studies from around the world, I found no preventive effect of any strategy initiated before birth, including prenatal classes specifically targeting postpartum depression. It's not because the interventions are theoretically weak, but it's because compliance is low - women are busy and don't attend the classes."

After sifting through hundreds of studies, Dennis conducted a systematic review and meta-analysis of 15 randomized control trials focusing on prevention of postpartum depression. The trials involved 7,697 women. Her study is published in the July 2 issue of the British Medical Journal.

The evidence suggests postpartum depression may be preventable, says Dennis. In analyzing the prevention strategies used, Dennis found an overall 19 per cent reduction in postpartum depression. Individual assessment and intensive support provided by a health professional to at-risk women after they give birth was the most successful approach to preventing postpartum depression; group-based strategies weren't as effective. Risk factors for postpartum depression include past psychiatric history, a significant number of life stressors and lack of support.

"Individual, flexible postpartum care provided by a health professional and based on maternal need may have a preventive effect," Dennis says. "You must have a structured assessment within the first four weeks after birth with referrals to appropriate services that are accessible."

Dennis says her findings have implications for clinicians. "This systematic review tells us what type of strategy we can use to help prevent postpartum depression, when and how we should implement the strategy and with which clients," she says. "It's a nice summary of current research that health professionals can use as a tool when seeking to treat new mothers."