So, you're home with your new baby and hopefully you're already starting to get back to yourself. The baby is getting onto a schedule and you're no longer stumbling around half-asleep. You're getting toward the end of your maternity leave and you're taking an honest look at your life; do you really want or need to go back to work or can you stay at home and raise your baby without depending on outside child care?
Figure out if the family really needs your salary (after deducting taxes, child care expenses and transportation costs). How will leaving work affect your social life? Do you have friends nearby who are also stay-at-home moms or are you the type who can strike up a conversation with another mother at the park? Feeling isolated and alone is a common problem for stay-at-home moms so you should think about ways to avoid this.
Are you leaving a menial job or an interesting career? Talk to coworkers who took time off from work to raise their family and then came back. What was their experience? You can keep up with your field by staying in touch with coworkers, professional associations and journals so that when you decide you want to return to your field, you'll be ready. Alternatively, you can investigate possibilities in your company for telecommuting, staying at the same job but cutting down on your hours, or switching to a job that's closer to home, thereby eliminating hours of commuting a week. Freelancing can also bring in money on a more flexible basis.
Whatever decision you make about going back to work or staying home isn't carved in stone; if you see it's not working out - one way or the other -- re-evaluate and see what kind of changes your family needs.