A common theme of studies into retirement planning is that a growing number of Americans is, for a host of reasons, delaying their golden years. Offering further insights into this trend is Towers Watson, which in a new report explores which workers are delaying retirement and why.

A key finding of the report is that American workers, most notably men, are entering the workforce later and staying on the job longer. In 2013, nearly a quarter of men over age 65 (24 percent) were in the workforce. This compares with 17 percent in 1990, a 7 percent increase. Among women, the labor force participation rate of those over 65 in 2013 was 15 percent, a 6 percent rise from the 9 percent participation rate recorded in 1990.

What’s fueling the upward trend? The report attributes the rise to both economic factors and changes in the workplace.

“Some retirement delays are prompted by caution, with workers deciding to extend their careers to buffer any future stumbles in the financial markets,” the report adds.