Kilee Nickels, 24, stay-at-home mom

Children: 21 month and 4 month old boys

Best time to have a baby? Early 20s

I got married at the age of 20. At the time, I was studying for a degree in nutrition. School is important, but I wanted to be a mom first.

I was pregnant at age 21. I knew I was ready to be a mom because I had an inexplicable feeling that it was the right decision. My first delivery was five hours, and my second was 20 minutes, and I didn't use an epidural for either baby. I think I'm built for childbirth. It was the most painful yet rewarding experience.

My typical day starts with making breakfast for everyone. When my husband goes to work, I tackle laundry, then dishes. Then it's playtime. When the baby naps at noon, I play with trains and read to the other one. I'm always trying to catch up with housework, often with a crying baby strapped to my chest. Sometimes it's hard — I can't wear nice clothes because I'm always getting peed and spit up on. I have no personal space or time to exercise. I'm not as toned anymore, and although it's hard to accept the fact that, at 24, I already want a breast-lift, I'm not as focused on being skinny as I used to be, which is a good thing.

It's smart to have kids when you're in your early 20s so you have the energy to keep up with them. More importantly, consider whether or not you're in a stable relationship. I hear about women becoming single moms, and I don't know how they do it. You really do need a partner. If you don't have a husband by the time you're ready to have kids, then you should wait until you find him. And the guy has to really want kids, because romance is tricky with babies.

I'm so happy that I had my kids young. But sometimes I envy my friends who are socializing and advancing in their careers — I'm still figuring out who I am, while also juggling the roles of wife and mother. But when my kids smile, I feel so proud. I want six kids, so I'll get pregnant again soon. Hopefully I'll be all finished having babies by the time I'm 35.

mom

Shannon Sweeney, 40, lawyer

Children: 6½ Months pregnant with a girl

Best time to have a baby? early 30s

I was married for only four months when my husband suddenly left me. About a year after the split, I was 38 and childless and felt like I was racing against the clock, so I started considering IVF. I was open to the idea of dating, but I was also ready to have kids right away — not ideal. I decided to see a fertility expert, who said I was a good candidate for the procedure.

I visited a sperm bank that specialized in donors with Ph.D.s — wanted a really smart kid! The search for a donor is not unlike dating: You're on the hunt for a cute, smart, healthy guy. I chose the father of my future baby on my 40th birthday. The clinic let me listen to his voice on tape and read essays he had written, which put me at ease.

It took three rounds of IVF and $50,000 of savings, but when I finally got pregnant, I experienced both bliss and fear. My whole life changed in an instant. Because I'm pregnant and dating, it's awkward. My body is changing, and I'm gaining weight, which is not so fun for a woman. You always hear men say how beautiful pregnant women are, but they say that because they're married to them! I'm pregnant with another man's baby — that has to be a weird turn-off. Are guys thinking about that in bed?

It would be wonderful if I met someone who could enhance my daughter's life. The problem is, it takes a long time to get to know someone, and there won't be time to do that before my daughter is born. And I wouldn't want to expose her to a relationship that's not serious.

For the most part, people support my decision to have a baby alone, but I have no doubt that there are critics out there. Some people feel I'm brave, while others judge. My doctor says he wishes women would come to him at 30 rather than 40. I'm torn on that because I'm happy I'll be a mom right now. I feel more at peace with my life than ever before — yet he may be right.

Raising a child alone will be difficult since I'll be the breadwinner and the caretaker. There will be no one with whom to celebrate the milestones, like her first words, and I won't have the benefit of my partner's perspective on weighty matters, not to mention the love and affection of a man. And I'd love for my daughter to have a male role model. But I will be honest with her when she realizes that everyone else has a daddy except her.

Hopefully I'll meet a guy I'll want to have kids with. But if not, I have more eggs and sperm on reserve. I never say never.

mom

Leslie Yazel, 40, newspaper editor

Children: 4-month-old girl

Best age to have a baby? 40

When I announced that I was pregnant at age 39, my Facebook wall blew up. A friend from my hometown in Iowa typed, "My kids are in high school, and you're going to have a newborn!!!"

I always had this vague idea that I would be a mom in my early 30s, but I had a passion for writing and spent my 20s and 30s traveling the world for work, so motherhood fell to the wayside. At 22, I moved from Iowa to London to San Francisco, covering the tech industry as a business reporter. By 26, I was living in Manhattan, writing for various magazines, and then took time off to trek through Bosnia and Croatia on travel-writing assignments. Finally at 34, I became one of the youngest editors on the Style desk at The Washington Post, editing Pulitzer Prize-winning writers.

To say that motherhood wasn't a priority was an understatement. When I was 33, I started dating Jeremy, my perfect match—a man who could be happy with or without children. When I was 36, we got married, and there was an instant expectation that we'd start churning out kids. "Will you start trying after the honeymoon or wait a year?" asked well-meaning but nosy relatives. "We probably won't have them," I'd answer firmly, thinking that if I sounded confident, people would leave me alone.

There's a pivotal scene in the movie Sex and the City 2 where Carrie and Big decide to remain childless. "It's me and you, just us two," says Carrie. Jeremy and I adopted that sentiment, growing comfortable in our fabulous lifestyle. With Jeremy working at The New York Times, we were commuting back and forth between New York and Washington, D.C. every weekend, and the time apart felt exciting and romantic.

But soon, coming home to an empty house every night and cooking dinner for one felt lonely. Work seemed less exciting. We decided I'd move to New York, get off birth control, and see what happened.

Three years later, I still wasn't pregnant. I was kicking myself for not having babies earlier, but I couldn't even consider IVF. I figured if I can't get pregnant on my own, I should listen to my body and accept the fact that motherhood wasn't in the cards for me. I didn't want to fight Mother Nature or shell out thousands for scientific methods. We tried to stay positive in the face of the increased risks — autism, Down syndrome, miscarriage. Yet my doctor assured me I was healthy, and I felt the possible rewards outweighed the risks. Finally, at 39, I got pregnant.

In my 20s and 30s the notion of kids triggered a mini panic attack: Will I ruin my body? Will I ever get promoted? How can we afford it? But I knew I was ready to be a mom at 40 because the thought of kids made me feel calm. And because both Jeremy and I were successful, we didn't have too many financial worries.

I look at my friends in their early 30s who don't have time to read a book for an hour because they're chasing after a toddler. But I've had a few decades to be totally selfish, so I'm OK with the fact that I don't have time to myself. We can't suddenly jet off to Hawaii, but what we have now is so much better.

When I was younger, having to leave the office at 5 p.m. to relieve a nanny would have irritated me. Now I don't feel guilty because my baby has given me a greater purpose. And being a mom helps me manage my time at work better, so leaving early isn't stressful. And when I get home, I switch right into being a mom. I couldn't have done this as seamlessly in my 30s.

I can't pretend it's easy all the time. It bothers me that my daughter won't have her grandparents around for a very long time. And because my metabolism isn't as fast as it used to be, I have to work extra hard at keeping off the baby weight. My body just isn't that elastic anymore — I couldn't have accepted this when I was younger. And I can't retire. I'll be 58 when my daughter finishes high school, and I'll be facing tuition bills while my friends plan to stop working. It's a good thing I really love my job!

What Do You Think?