Main Line Health has not lost its status as a financial juggernaut, but the system has felt financial pressure in recent years from rising expenses, inpatient volume swings, and weaker reimbursement, Fitch Ratings said even as it gave Main Line's proposed $105.5 million bond offering a 'AA' rating, which is third from highest.

The strengths of the nonprofit system, which owns four acute-care hospitals, include its trove of $1.47 billion of unrestricted cash and investments and an extremely low debt load of $285 million, including the new offering, which will be used to pay off old debt and pay for a portion of capital projects at Lankenau Medical Center and Bryn Mawr Hospital.

A three-year decline in operating margins at Main Line Health continued into fiscal 2017, which ends this month. In the nine months ended March 31, Main Line had an operating margin of 2.4 percent, a five-year low, according to Fitch. The health system reported nine-month operating income of $30.26 million on revenue of $1.26 billion. In the same period a year ago, Main Line had $71.33 million in operating income on revenue of $1.24 billion.

"We are working proactively to position ourselves positively for the future in an ever-changing health-care landscape," Main Line spokeswoman Bridget Therriault said.

Fitch said Main Line had identified ways to increase revenue and reduce expenses by fiscal 2020 under a program called Performance Excellence 2020. The system's budget for the fiscal year starting July 1 is expected to include $21 million in benefits from the effort, after consulting expenses, Fitch said.

"Fitch expects Main Line to at least stabilize operating performance in fiscal 2018, with steady improvement over the next several years that will be necessary to fund its substantial capital projects without diluting the balance sheet to levels below comparable rated credits," the ratings agency said.