Despite the slow economy and credit crunch pushing many developers to the sidelines, healthcare real-estate investment trusts are expanding their development pipelines. Some of the biggest health-care REITs by stock-market value are expected to build $675.9 million of properties by year's end, up from $236.5 million in 2007, according to stock-research firm Stifel Nicolaus. Aging baby boomers who want cheaper outpatient care are fueling demand for medical-office buildings, said Stifel Nicolaus representatives.