When most people think of the changing American family, they probably consider the rise in divorce and single-parent families. But according to author Laura Scott, another trend among American couples is to have no children at all -- and not because they can't have them, but because they don't want them. She outlines this theory in her new book, "Two is Enough: A Couple's Guide to Living Childless By Choice."

The book is based on her own experience (Scott is 48 and has been married for 21 years) and three years of research, including an online survey of 171 self-described "childless by choice" people and more in-depth interviews with 30 couples. While she interviewed some singles, her focus was on couples because, well, people expect couples to have kids.

And Scott and her subjects aren't alone. It's true that in 2000, U.S. census figures show that families who had children had an average of 1.86 kids. But not every household hears the pitter-patter of little feet. In 1976, 10 percent of American women between the ages of 40 and 44 had no children (by choice or by circumstance). By 2006, that number had doubled to one in five, or 20 percent. While clearer studies haven't been done to separate the reasons of choice versus circumstance, Scott says "to assume that all couples will be parents is unrealistic." Here are the realities she did find while writing her book.

AOL Health: How did you come up with the concept for this book?

Laura Scott: I was working as a writer and journalist and screenwriter, and came across "The Childless Revolution," by Madelyn Cain. It was mostly about women who were childless by circumstance. I realized that there wasn't a lot out there that had been written about people who intentionally remained childless. [For me] that maternal instinct never kicked in. And I thought, are we right to believe that all women will have this instinct to have a child?

AOL Health: How did you and your husband agree not to have kids together?

Scott: We as a couple would check in with each other periodically. Five or six years would go by and we would say, "Do we want children?" The answer was always "no." It is a process. It's important for couples to have the conversation early, before marriage. If you don't agree on childlessness, it can be a deal-breaker.

AOL Health: Do you think your partnership is stronger without kids?

Scott: Yes, I think it is in some respects, because we have more time to focus on each other. Women really appreciate the fact that they have quality time with their husbands and they can build a really strong relationship because frankly that's all [couples like us] have. We're a family of two.

AOL Health: What are some major myths associated with childless couples?

Scott: I think the biggest misconception is that those who are childless by choice don't like children. I interviewed a lot of teachers and people who had jobs that happily put them into daily contact with children, so I don't think that holds water at all. Another myth is that we're going to regret the decision we've made. You make this choice and you live with it, and you build your life around it. I [also] think there is an assumption that people make this choice because they had a terrible childhood. A lot of people said, "I had a great childhood."

AOL Health: Do economics play a factor in this trend?

Scott: We're dealing with a lot of issues as a society right now [like the recession] that make remaining child-free a legitimate option for couples. I think economics plays a huge part because it causes us to postpone childbearing. The longer you postpone, the fertility window for women shrinks. Things fill the gap, like jobs and leisure interests and then ... you might get comfortable in a family of two. One of the biggest motives [in my researching] for both men and women was that they love their life the way it is, and having children won't enhance it.

AOL Health: How much do you think the media plays into the myth that every couple wants kids?

Scott: A lot of celebrities give us the impression that life was miserable before kids. In every magazine we see "bump" alerts, celebrities being photographed in their seventh or eighth month [of pregnancy] or with toddlers in hand. There are some women [who read these magazines] who are childless by circumstance in their 30s and 40s, and want to believe that this option is still open to them, even though they've postponed childhood for 20 years. We didn't see a lot of new moms at age 40 years ago. And the fact that some of these women are doing it as singletons -- that's news. But those that remain childless by choice don't make the news. I like Rachael Ray. She's one of the childless role models we have.

AOL Health: What's one drawback to being childless by choice?

Scott: When you get into your 30s and you're the only person in your peer group who doesn't have a child, it can be socially isolating. [Potential friends] are focused on their children and their social circle is comprised of other parents.

AOL Health: Were your parents freaked out by the prospect of no grandkids?

Scott: I told my mother when I was 15 that I didn't want to have children. She thought maybe I would change my mind. Luckily my parents never really pressured us. That wasn't true of many couples I interviewed.

AOL Health: What have you done that you don't think you would have done if you were a mom?

Scott: Writing this book is one thing. [My husband and I] do off-the-beaten-path traveling, which requires physical stamina and some risk to your health. I don't know if I would do that if I was 65 [after raising kids and retiring]. We've also taken huge financial risks as entrepreneurs. We invested in the company my husband works with now and we mortgaged our home to the hilt knowing that if we were to lose it all, it would be just him and me living in a trailer park, and we wouldn't be sacrificing our kids' college funds.