Women's prolonged absences from the workplace while providing care—either to children or to other relatives—means they're not there as long as men are, in front of higher-ups responsible for their advancement, to get promotions and move up the corporate ladder.

As a result, they're often passed over for moves into middle and higher management, and their pay grades suffer as a result.

In fact, according to a 2015 Washington Post poll, 62 percent of mothers have actually quit their jobs, or else worked fewer hours or accepted less demanding positions so that they'd have time to devote to child care. Just 36 percent of fathers have done so.

And a Pew Research Center study cited in the report found that 29 percent of mothers stayed home completely in 2012, after hitting a record low of 23 percent only 13 years before—in 1999. Needless to say, women who aren't in the workforce don't have access to an employer-sponsored 401(k) and a match that can increase their retirement savings.

So if women don't have retirement savings, how are they getting by once they do retire? Kids.

According to a 2015 TD Ameritrade survey, adult children are almost twice as likely to be supporting a mother—at 42 percent—than they are a father, at just 23 percent. Oh, and even as kids supporting parents, women are overwhelmingly the ones supporting the parent, with 91 percent of those supportive children being female.

So what's wrong with this picture—especially on Mother's Day? Namely, that after taking care of everyone else in the family Mom might be on her own when it comes to retirement.

Maybe instead of a box of chocolates or a bottle of perfume, you should sit down with your mother on Sunday and present her with a contribution to her retirement plan—and have a little chat over the Irish coffee about how she can boost her own savings via regular and catch-up contributions to any 401(k) and IRA accounts she may have.