"First you have to see what you have," Astre says. "Sometimes there just isn't enough to protect anyone."

Cindy Hounsell, president of the Women's Institute for a Secure Retirement, or WISER, suggests that couples sit down together and make a checklist of the income that will exist before and after the death of each spouse.

"When people are thinking about retirement, they have to think about where the income is going to come from, and which pieces are going to last for the rest of (their) lives," Hounsell says.

If your spouse has retirement assets in his or her own name, include it in the mix, and factor in whatever life insurance policies you have with your spouse as the beneficiary.

"Most public employers are going to offer some amount of life insurance benefits, separate and apart from the pension fund," says Keith Brainard, research director for the National Association of State Retirement Administrators.

If you don't have life insurance, consider whether you need to buy it for extra spousal protection. "If you die, your spouse gets the IRA, but is that going to be enough for him or her?" Astre asks.

However, if you're going to buy life insurance, do it before you retire. As you get older, life insurance becomes much more expensive, and the available policies usually won't offer much coverage, he says.