Also read: Women less prepared, more worried about retirement

Women, of course, still bear a lot of the responsibility of family life, so they more typically take career breaks or move into part-time work – facts of life that can really hobble their ability to save enough for retirement. 

To their great credit, Aegon and Transamerica did more than produce yet another gloomy report on retirement.

Instead, they also offered a series of recommendations designed to help put things on track, including greater adoption of auto-enrollment and auto-escalation in 401(k)s. No. 1 on their list, however, is an idea very likely to meet a lot of resistance from employers, especially smaller ones.

The idea? Extend workplace retirement plans to cover part-time workers.

Transamerica has been promoting this idea for a few years, in fact, and there's nothing really radical about it.

Some larger national employers have been doing it for more than a while, including Costco, JP Morgan Chase, Lowe's, U-Haul and Starbucks.

Still, according to Transamerica's figures, just 49 percent of 401(k) or similar plan sponsors allow part-time workers to save in their plans.

Worse yet, 90 percent of those that don't also don't plan to do so in the future.

Also read: Part-timers struggle to hit full-time status

Their most frequently cited reasons include that doing so is generally impractical (49 percent). These employers also worry about raising costs (36 percent), and the high turnover rate among part-time employees (28 percent).

I don't really buy the concern about practicality. It sounds like a paperwork excuse that's probably related to the high turnover problem. That turnover issue, in fact, is much more understandable. Why bother to extend retirement benefits to someone who'll be gone in six months? But the fact is that a growing share of our part-time workforce is in it for the long haul. It seems like a fairly simple matter to require a part-timer to put in six months before they're eligible to join the company plan.

Concerns about costs, meanwhile, may be simply overblown.

"There's not a one-size-fits-all approach, so we do recommend employers consult with their advisor. Some things may cost far less than they imagine," said Catherine Collinson, president of the Transamerica retirement studies center.

That's good advice from Collinson, but were I an advisor, I'd simply forward this column to your prospects. You can tell them I sent you.

Employers might also consider this basic fact: opening the plan to part-timers should mean higher plan balances, and plans with higher balances see lower fees.

Because it's a nonprofit, Collinson's center is prohibited from lobbying federal lawmakers. She has, however, testified on issues before Congress, notably on the saver's tax credit.

I'm speculating here, but Congress could well invite her to stop in again next year, should it decide to tackle retirement reforms.

The idea of mandating employers to extend retirement benefits to part-timers is not on anyone's list. That's a good thing, because there are some items that government should just never mandate.

But if you're an employer, it sounds like a reasonable, fairly simple thing to do, especially if you want to retain smart, hard-working moms who somehow manage to juggle a gazillion things at once.

Also read: Women need a retirement strategy