Cheryl and Ellis Levinson believe they made a very grown-up decision not to have kids.

It was early on in their 28-year relationship when the San Jose couple conceived their emotional choice. While Cheryl, a psychotherapist, had never yearned to give birth, Ellis, who worked in entertainment and journalism and now has a consumer blog, had once dreamed of having his own offspring.

Yet, as they matured together, they began to observe the risks of bringing children into the world — everything from dangers to the children themselves to the risks to a planet already burgeoning with overpopulation, suffering exhaustion of its natural resources and tainted by climate change and pollution.

“There are now almost 7 billion humans in the world, going to 9 billion in 40 years and increasing by 40 percent by the turn of the century,” Ellis says. “The threat to human survival cannot be understated — water depletion, air pollution, disappearance of the wild. And when you’re creating a new person, you’re rolling the dice for the child as well — there’s mental illness, abuse, drugs, incarceration, poverty — it’s not always this TV commercial happy family. It’s an incredible gamble.”

They’re not saying don’t have kids, Ellis adds. “We love kids,” he says. “It’s just that many people don’t give procreation the deep deliberation it deserves. Maybe have one child, but two? Three?

“So, we’re saying, think about it. Then think again.”

The Levinsons recently published, “Enough of Us: Why We Should Think Twice Before Making Children” (iUniverse), a book that advocates for being “childfree” amid what the authors view as a society that encourages procreation through family and religious pressures and even tax benefits. They say Western culture has elevated the parent-child unit to “lofty and honored heights,” while casting off the childfree household as less than a true family unit. And they want to initiate a national discussion on the issue.

Free versus lacking

Many couples, and particularly women who choose not to have offspring — preferring the term “childfree” to “childless” — say they’ve experienced this kind of disdain.

When Gail Watts, of Hayward, first got married 15 years ago, she was bombarded with questions about when she and her husband planned to have babies.

“I would get so frustrated when people would challenge me as to why I was choosing not to have children. No one would ever question my husband, who had made the same choice. Apparently, it was OK for him, but people would be confused and even angry that I, as a woman, didn’t (choose to have kids).”

Lauren Sandler agrees. She’s the author of “One and Only” (Simon & Schuster), which seeks to dispel the notion that only children are dysfunctional and maladjusted brats.

“There’s this ridiculous mythology that if you don’t have kids, you must be selfish, and that if you have only one, it’s a terrible thing you’re doing to your child,” says Sandler, who has one 5-year-old daughter and was an only child herself.

As someone who doesn’t list her maternal identity first in her life but also values outside friendships, romance and career, Sandler finds she frequently has to explain her choice of family size. “No one ever has to defend or give philosophical reasons for two or three kids. Of course, more than three, you’re marked as a breeder,” she jokes. “You just can’t win.”

When asked if they have children, the Levinsons usually try to keep it light, while clearly indicating their childfree existence is intentional. They’ll say, “I hope not!” or, “We’ve spent thousands of dollars on contraception.” Cheryl often says that she has chosen to be a mother of dogs.

Born to bear?

Sandler views society’s push to have children in evolutionary terms — originally for the survival of the species, then as a workforce in an agrarian society. When the Industrial Revolution came along, children suddenly began to cost instead of earn, she says.

“Then the women’s movement happened, but we didn’t really come to terms with what women’s freedom looked like, and how much society had changed,” Sandler says. “So we kept telling this story that humans needed to have kids and that adult women could only have value if they were mothers.

“And today there’s more and more obsession with babies and motherhood than ever, with blogs and stores and books,” she says. “We’re in a very pro-baby generation.”

Kara Harpham-Barlia and her husband, Mike Barlia, of Oakland, are both 39, and each has a veterinary practice. They’re members of a global Childfree By Choice listserve. Harpham-Barlia says her eyes were opened early on to the immense work and responsibility of having kids.

“When I was a teenager, my parents decided to have more babies, so I really got to see how much work it was, how much it cost,” she says. “I wasn’t committed to being childfree at that point, but it really made me think about it.”

For her husband, it was never a difficult decision. “I enjoy being an uncle and watching my niece grow up,” he says. “I feel incredibly fortunate to be married to my best friend and have the opportunity to travel and spend time together. I work with an amazing group of people in a career that I find very satisfying and rewarding. I honestly do not feel anything is missing from my life that would somehow be fulfilled by having a child.”

To have or have not

The Levinsons realize the target audience for their book is made up of those who are already carefully pondering childbirth. To reach a broader base, they hope to start a national discussion on the way government policies and businesses favor larger families, and they want to encourage adoption of children who already exist.

“We need to rethink the reasons for having offspring,” Ellis says. “I can’t think of any reasons that are not selfish — a little immortality for yourself, trying to salvage a bad marriage, living your own unfulfilled dreams, maybe having someone to care for you when you’re old.

“Cheryl and I have asked dozens of people why they have kids and they most often say, ‘That’s a good question. It’s just a thing people do.’ But that’s not a very good reason, either,” he says.

Erica Smith, 27, of San Jose, is wrestling with the decision to have or have not, and — either way — she wants it to be an informed, researched, confident move.

In talking with friends, family and co-workers at her hair salon — those with kids and those without — Smith has come to realize bearing offspring is not for everybody, and it’s not necessarily the next step for her.

“There are so many issues,” she says. “My parents are pressing me to have a kid. I think that’s a big reason people have kids, is for other people. Kids are expensive, especially in the Bay Area, with the right education, clothing, food, music lessons. And a lot of people go into it without the money to take care of them. Everything you do affects them. If depression runs in your family, you might be dealing with that with a teenager.”

Smith says she may decide to have kids but wants to go into the decision with her eyes open. “I don’t want to have babies just to have babies.”

Follow Angela Hill on Twitter @giveemhill, or read her Sunday Give ‘Em Hill column.