She praised the human resource managers gathered for their conference. “You know what it takes to provide workers the flexibility and benefits that they need to care for their children,” she said.

At a time when almost everything Mrs. Clinton publicly says feeds presidential speculation, she has also used the speeches to address issues like the Arab Spring, the conflict in Syria and the former National Security Agency contractor Edward J. Snowden.

Mrs. Clinton does not make her speechmaking schedule public, but the trade groups typically publicize the events. A spokesman for the former first lady declined to comment.

But her political rivals have already started to keep tabs on her speaking schedule, looking for any hint of a conflict of interest. (So far, Mrs. Clinton’s staff appears to have carefully chosen where she has given speeches, avoiding paid talks to potentially controversial groups.)

“We’re starting immediately to monitor both Hillary and the other Democratic rising stars and collect, tag and characterize their speeches so we can hold them accountable when the campaign begins in earnest,” said Tim Miller, the executive director of America Rising, a conservative political action committee.

Mr. Miller said that it was too early to send operatives to covertly buy tickets to Mrs. Clinton’s speeches, but that the group was watching from a distance “to monitor whether she’s hobnobbing with investment bankers in New York City that might seem like favoritism down the line.”

Since Mrs. Clinton stepped down as secretary of state, she has divided her time between writing a memoir and juggling a growing schedule of engagements, paid and unpaid. The unpaid appearances are typically focused on her advocacy work for women and girls as part of the Clinton Foundation, the charitable organization founded by her husband. (She is not completely avoiding politics, and will campaign for Terry McAuliffe, a family friend who is running for governor of Virginia.)