Are you ready for another one?

No one can answer that question but you, and boy, is it a tough one. Some say it's even more difficult than deciding to have a first child. You're not just talking about having a baby, you're talking about changing a family. With each new child you have to think about how that baby will affect your lifestyle, finances, work, relationships, and, of course, your other kids. And if you listen to the word on the street, growing your family by one means more than double the work for Mom and Dad.

Read on for some of the things you should consider before welcoming a new baby into your house. Just about everyone — from doctors to scientists to your friends and neighbors — has an opinion on the perfect time to have another baby and the perfect size for a family. Weigh the pros and cons and then make your own decision. And if you'd like to talk with others about this complicated issue, stop by one of these bulletin boards: The best time to have a child; Life with a large family; Parents of onlies.

When is the best time to have another?

For many people the decision to have another child is more about when than whether. And plenty wonder if there's an ideal spacing between children — for the adults and the kids. The big question: Is it best to have children one right after the other so they can play together and you can get all your child rearing done in the shortest time, or is it better to put some distance between the kids?

Researchers have tried to tackle this question, and while they can't say definitively that every woman should wait two to three years between births, many of the studies do settle roughly on that time frame. And so do most families. According to the Alan Guttmacher Institute, the average interval between first and second births is about 30 months for American women.

Here's a rundown of the studies on ideal baby spacing: • Waiting 18 to 23 months after the birth of your last child before conceiving another seems best for the new baby's health, according to a recent study published in the New England Journal of Medicine. Doctors found that babies conceived less than six months after the birth of a previous child are 40 percent more likely to be born prematurely or underweight. And those conceived more than 10 years after their closest sibling face about double the risk of preterm birth.

• A similar study at the University of California in San Francisco found that the ideal interval between babies is 24 to 35 months. Babies conceived sooner had a higher incidence of low birth weight. Doctors suspect a mother's body may need that time to recover from the stress and replenish all the nutrients she lost as a result of the first pregnancy.

• When your first is under 1 year or over 4 years is the ideal time in terms of the children's relationships with their parents, sibling rivalry, and their own self-esteem, according to Jeannie Kidwell, a professor of family studies at the University of Tennessee in Knoxville. She believes children under one don't have a sense of their special status yet, and that those over four have had enough time to enjoy attention from Mommy and Daddy, plus they now have a life of their own.

What should I consider when making the decision?

Science doesn't dictate all the choices we make, of course, especially the ones that involve love and desire. So here are some other issues to take into consideration as you wrestle with the idea of welcoming another baby into your family.

How old is your other child (or children)?

There is no right or wrong answer here, though it seems clear from the research above that it wouldn't be wise to get pregnant if you're the parent of a child under 6 months. People go both ways on this question. Some think the older your other children, the better. That way they've had plenty of time with you and they can understand and even talk about the effect another child might have. Others think spacing your children close together ensures they'll be playmates for life, and that you won't be spending the rest of your life raising small children. Listen to these moms and decide for yourself.

• "My two boys are three and half years apart and I think that spacing is great," says Susan W, an executive at a publishing company. "Since my older son was out of diapers by the time the younger one was born, I could fall in love with the idea of having a baby again. And they're clearly in different arenas so I don't see a lot of sibling rivalry. They really enjoy each other."

• "My first two are three and half years apart. That gave me time with the firstborn alone," says Janet L, an advertising copywriter who is pregnant with her third child. "I think the older the child, the better, because they're that much more independent and can mentally and emotionally handle the baby. In some ways I wish there was a bigger age gap between my second child and the new baby — they're only two years apart. I'm dreading having two in diapers at the same time. And I'm worried about the physical challenge of having two who need so much time."

• "My three oldest children are all about a year and half apart, and though it was tough when they were all babies, in many ways it was great," says Barbara M, a geriatric therapist. "They really amused each other and have stayed very close. I'm one of four children myself and I really wanted to re-create that big family feeling."

How will another child change your lifestyle?

Are you settled into a nice routine with your other children? Do you have a good childcare system set up? Is everyone else finally sleeping through the night? Perhaps you've gotten to the point where you and your partner have time for each other again. Maybe you've gone back to work and you love it. These are all important considerations when you're thinking of having another. Remember, a newborn will take over your life. Consider whether you have the time and energy an infant requires, and whether your children are ready to deal with the reality of a baby in the house. You may end up deciding that one is enough.

What's your financial situation?

We're the first to admit that money isn't everything, but you sure do need some when you're raising a family. Considering that each child costs about some thousands $ a year to feed, clothe, house, and keep healthy (and that's a conservative estimate in many parts of the country) you'll want a little extra in your monthly budget before you conceive another child. It's important to consider your work situation, too. Many women find it more difficult to keep up with full- or part-time work once the second or third child comes along. Can you afford to quit work, if that's in the picture for you, or pay for the new baby's childcare if you want to stay on the job?

"My daughter is almost 4 and we haven't had another yet because we're worried about affording everything," says Stephanie N, a college lecturer. "We didn't have much money when we had our first so we know what it's like not to have the resources to pay for things. That's why we want to be better prepared for the next one. Money is a huge consideration because of childcare costs. The other big thing is career. I stayed with my daughter her whole first year. I would like to do that with the second child, too. We want another; we're just not sure when. It already feels a little late to me."

How old are you?

Unfortunately age is a factor, especially for women. If you're 38 years old and you want two more, you don't have the luxury of spacing them three years apart. But if you're under 30, and you don't have any health problems that could make conception difficult, you can be a little more flexible with your timing. There are no hard and fast cutoffs in terms of age. Many women can still get pregnant in their early 40s, but fertility rates do drop dramatically once you reach 35. (Learn more about your chances of getting pregnant at different ages). Talk the age question over with your partner. Many people have preconceived notions of how old they'll be when they're finished having children.

Do you and your partner agree?

Sometimes one partner is ready and the other isn't. It's hard to be in sync all the time. This is a tough one to settle, but the first step is to start talking about your differences. Sit down together and discuss your points of view. You may not solve anything at that moment, but you'll have a better understanding of the issues. It might help to talk to others in this situation, too. This problem is so common, we created a chat called I'm Ready for Baby, but My Spouse Isn't. Stop by and share your thoughts.

What does your heart say?

Sure, you can sit down with a big legal pad and run through the pluses and minuses of having another child. But this is one of those decisions that's led by the heart, so go ahead and follow yours. If you want another baby, and your partner (if you have one) wants one too, there may be no time like the present.