With a booming maternity line, a TV show, a new book and three children, everything in British-born Ms. Pope’s life is rather Rosy.

I may be known as a fashion designer, but my first passion was…science! I actually studied neuroscience at Columbia University before the start of my career. During that period, my husband, Daron, and I were thrilled to learn I was pregnant, but sadly I suffered a miscarriage. I was left with all these questions, and my scientific background impelled me to seek out medical experts to find the answers I needed.

Around the same time, I began designing custom maternity gowns. They were priced from $2,000 to $10,000; in retrospect, it was a very risky move to begin my fashion career in couture. When the recession hit, I had to rethink my business. In 2008, I decided to create an affordable yet high-end maternity line—and Rosie Pope Maternity was born.

Video: Rosie's maternity clothing tips

Moms-to-be who came to shop in my SoHo store had lots of questions about
their pregnancies…and I had lots of answers! This inspired me to launch MomPrep, a maternity concierge service that includes classes and seminars to help prepare for both pregnancy and new motherhood. I didn’t just want to dress women fashionably for nine months, I also wanted to give them solid, researched information (there’s that science again) to help them make informed choices.

In the throes of designing and teaching MomPrep classes, Bravo TV approached me to host the reality show Pregnant in Heels. Being on television helping so many women has been an amazing yet humbling experience. We tackle tough issues like vaccinations and home births, but at the end of the day, it’s all about being a parent.

Along with our stores in New York and Santa Monica, CA, and online, we’re planning to open two more Rosie Pope shops, in New York City’s Tribeca area and Los Angeles. Since our goal is to reach as many moms as possible, we’re creating a second, more affordable maternity line. Daron has come on board as president and CEO of Rosie Pope Maternity. And I just penned my first book, Mommy IQ, a companion guide to help pregnant women from conception to birth.

Of course, I’m doing all of this while I’m having children—three in the last five years. Life is certainly crazy, but I just keep going. After all, it’s what I asked for: I wanted a big family and a successful business, but I didn’t think it would happen all at once! So Daron and I experience the adventure together. I figure I’ll sleep later. Or never. But I wouldn’t have it any other way.

1. Be passionate.
Your business has to be something you absolutely love. You can’t start one out of boredom or because you want to make quick money—it won’t work.

2. Be a believer.
Many people will try to discourage you from chasing your dream. You have to believe in your concept—and yourself as a businessperson.

3. Be patient.
Rome was not built in a day, nor will your business be. Success can take years to achieve, but it will happen.

4. Be money smart.
Don’t ditch your day job. That paycheck will allow you to take risks in your new business that you might not otherwise be able to afford.

—As told to Jennifer Parris