The childhood sing-song, "First comes love, then comes marriage, then comes Georgie in the baby carriage," is the rudimentary blueprint for coupling.
That is, for some couples. Others prefer stanzas one and two but elect to forgo three. They wish to be a family of two.
"I didn't set out to have kids, but I figured I would because that's what people do," said John Hillebrand, 39, of the Fort Worth suburb of Colleyville, Texas. "But it wasn't long before Ingrid and I realized we had things we wanted to do that didn't include children."
Ingrid Hillebrand, 38, said her decision not to have children was made in childhood, more or less. "Growing up, I just never saw myself as a mother. I was one of those kids who didn't want a family, other than a husband."
While choosing not to have children isn't commonplace among American couples, John and Ingrid Hillebrand, who have been married 12 years, are part of a trend toward highly educated couples opting not to have children. Dr.Hillebrand is an anesthesiologist. Mrs. Hillebrand holds two master's degrees, one in art history, one in German. She's a volunteer docent at the Modern Art Museum of Fort Worth and plans to return to teaching college-level German.
Census figures indicate more women are not having children. Sixteen percent of women born in the late 1950s will not have children. That compares to 8.2 percent of women of childbearing age in the late 1950s who did not have children, according to Amara Bachu, who studies fertility patterns at the Census Bureau.
"We don't know why this is happening," Ms. Bachu said. "We do know women are postponing births because they're entering the work force. Maybe these women are more fulfilled working so they chose not to have children. We really don't know the answer."
Little work has been done to provide a statistical breakdown of who is and who isn't having children, said Robert Littlefield, a psychology professor at Texas Woman's University and president of Family Psychology Institute of Dallas.
"Much of our knowledge is from clinical experience, which isn't as exact as we would like," Dr. Littlefield said.
But, he said, indications are that the highly educated, dual-career couples are the main group opting not to have children.
Reasons vary. Some couples consciously make the choice; others postpone the decision until age makes it no longer an option, said Dr. Littlefield.
Today, women have more lifestyle choices because of the availability of birth control, he said. "It's opened many avenues that even 20 to 30 years ago weren't available."
Having children is particularly difficult today, said Dr. Littlefield. "This culture doesn't support families. There isn't a place for kids the urban culture. Extended families aren't typically close by to help anymore. For some people, it feels like they're in prison for 20 years."
What about regrets? Couples often hear: Do you want to be alone in your old age? Don't you want to pass something on to the next generation?
Dr. Littlefield advises couples to do what's best for them. Having children or not having children offers no guarantee of happiness, he said.
Once the decision is made not to have kids, couples may look for other outlets for their need to nurture.
Being an aunt, Ingrid Hillebrand said, is her outlet. It allows her all the good parts of being a parent and none of the bad.
"I give them advice and they listen. So I have an effect on a younger generation," she said. "It's important to feel you have an impact on the generation that follows. Parents affect the world through their children. Childless couples can have an impact with teaching, volunteering, community service."
The reasons for not having children vary from couple to couple. Freedom and career are only the two most obvious. Some just don't feel a desire to reproduce.
"I never had that desire to be a mommy growing up. I played with dolls, but never thought about having a baby of my own," said Sue Dunaway of Fort Worth, Texas. "Having a baby is much more than that glow when the baby first comes home. It's that day-to-day grind of responsibility."
When Sue and Kenneth Dunaway, now in their 40s, married 25 years ago, they hadn't made the decision not to have children. It evolved. At first they waited because they wanted freedom from responsibility; then career became an issue, then other family responsibilities.
"We are both the oldest in our families, so we've helped siblings, who were 10 years younger, financially and emotionally," said Mr. Dunaway, senior production manager at Harcourt Brace Jovanovich College Publishers in Fort Worth. "We feel we've already raised four kids between us."
The final decision came because neither felt they were cut out for parenthood. "I know myself, the impatience I have and the perfection I expect," said Mrs. Dunaway. "I don't think that's good for a child. I know very few people who meet the bill."