Married women tend to be two to three years younger than their husbands, and retire two to three years earlier, the data suggests. That earlier retirement age “seems counterintuitive,” she said, “since women have longer life expectancies and have shorter careers due to delayed or interrupted labor force participation while raising children.”

Optimally, she said, women should retire at “older ages than men.”

The standard reason for retiring at older ages — given in “The Power of Working Longer,” the paper I cited in the previous column — is that monthly Social Security benefits rise appreciably if you wait longer to claim them. In one case on the official Social Security website, for example, monthly benefits rise 76 percent through delaying retirement from age 62 to 70.

But the greater monthly benefits that come from delayed retirement are based on the actuarial expectation that you will have fewer months left in your life to collect those larger Social Security checks. On average, for the population as a whole, total lifetime benefits are expected to be the same, regardless of when an individual starts to receive them.

That is true for the population as a whole, yet there is a fundamental problem: For men and women, all things are not equal.

Women generally earn less than men — about 81 cents on the dollar in 2016 for the median woman, according to the Census Bureau. That not only means lower lifetime income, but also lower monthly Social Security benefits. In 2016 filings, Social Security data show, women received $1,216.62 in monthly benefits, on average, compared with $1,592.43 for men — a difference of $375.81 per month.

With lower lifetime earnings, less in savings and lower Social Security benefits, retired women are 80 percent more likely to live in poverty than men, a recent study by the nonprofit National Institute on Retirement Security found. (Widows and widowers receive benefits based on their spouses’ earnings, if they are higher than what they would otherwise receive. But that doesn’t entirely erase the disparity for women.)

For those healthy enough to work longer and able to find suitable employment, delayed retirement can ease financial strain. “Working longer can provide more financial resources,” Professor Maestas said in a phone interview. “And it so happens that women right now tend to benefit more than men from working longer.”