Your home is not the biggest investment you'll ever make — your kids are.

You probably won't use cost as a determining factor in whether you decide to raise a family, but you can still benefit financially from some advance planning.

Insurance Issues

The most immediate issue when you're thinking of adding a new member to your family is how much of the associated cost will be covered by your health insurance. Estimate how much you can expect to pay out of your own pocket, based on the coverage provided by your health insurance policy. If you're covered under an HMO, you'll probably have a copay for each doctor visit (usually $10 to $25) and a copay for the hospital admission for the delivery (usually a minimum of $250 to $500). Check your policy to see what other costs you might incur. Be sure your doctor and the hospital are in your HMO network or you could be faced with some very large medical bills.

If you have an indemnity plan instead of an HMO, you probably have a deductible (usually $200 to $1,000) that you have to pay out of your pocket before the insurance kicks in. After the deductible, a typical plan will pay 80 percent of all other allowed charges, and you'll pay 20 percent, up to a maximum out-of-pocket expense (usually $1,000 to $3,000). After you've satisfied the out-of-pocket maximum, the insurance will pay 100 percent of usual and customary charges. Sometimes charges are only partially paid by insurance because they exceed the usual and customary cost for that service or procedure in your area, but if you ask, doctors will sometimes write off the excess.

Find out how much it will cost to add your new family member to your group medical insurance policy as a dependent. If you and your spouse have separate insurance policies, figure out if it makes sense for one of you to transfer to the other's policy. Dependent coverage may be cheaper if you're all on one policy, especially if one spouse has a cafeteria (section 125) plan and pays premiums with pretax dollars.

The FSA Option

If you or your spouse has an option of contributing to a flexible-spending account (FSA) at work, you could come out ahead by doing so. You contribute your pretax money to an FSA and request reimbursement when you have uncovered medical costs (such as your deductibles or co-insurance). You could save as much as 50 percent, depending on your tax bracket, because the amount you contribute doesn't show up as income on your W-2.

Income and Expense Issues

Once you have your bases covered on insurance, think about how you'll manage on one income during maternity leave and possibly reduced income during the pregnancy. Are you covered by short-term disability insurance? If so, you'll receive between 60 percent and 70 percent of your regular income for approximately six weeks following delivery, or sooner if you're deemed medically unable to work during your pregnancy.

Arrange child care well in advance. It takes time to interview potential providers and check them out with other parents who have used them. Child care is a huge expense, so figure the costs into your budget ahead of time and come up with ways to make cuts elsewhere if necessary. Childcare expenses are tax-deductible (within limits), as long as your provider is licensed and you provide her social security number to the IRS.

As soon as you have your first thought about having a baby, start a baby fund to cover unexpected costs, and contribute to it monthly. Shop for bargains on baby equipment and supplies, but don't skimp on items that affect safety, such as high-quality car seats. Don't go overboard on toys and baby accessories that will be quickly outgrown and that the baby is too young to appreciate. These add up to big bucks.