The impetus for Debbie Slevin’s book, “Unpregnant Pause: Where Are The Babies?” was an odd fact that struck her a few years ago when she was at her book group.

Ms. Slevin, 61, and her husband, Jeff, live in Edgewater now — they’re empty-nesters and were more than ready to exchange a large house for a cosy place with less demanding maintenance and a river view — but until a few years ago she lived in Demarest. “We” — the eight women in the group — “raised our children together, we were in the PTA together, and since then, for the last 15 years, we’ve belonged to a book group together.

“One night I looked around, and I realized that we had seven daughters among us. Two of the women there were grandmothers — both from their sons — and our daughters are all in their 30s — but none of us were grandmothers through our daughters.

“None of them was married.

“We all thought that was weird.”

That initial insight led her to “start asking questions everywhere. Wherever I went — to the nail place, shopping, in Starbucks — whenever I saw women about my age, I would ask them if they had grandchildren.

“A pattern started to emerge.”

The pattern showed itself among “metropolitan, upscale, well-educated” young women — the daughters of the women she approached with her questions, Ms. Slevin said. (It is far less common among more religious observant women, Ms. Slevin added. Those women tend to marry earlier and begin to have children earlier.)

“It’s particularly marked among women who have gravitated to cities because they want to make their mark. In my book, I compare Sheryl Sandberg’s book, “Leaning In,” with Susan Patton’s “Marry Smart: Advice for Finding THE ONE.

“Sandberg says wait until after college, give at least 15 years toward making a career. Patton says you should find your man in college because you will never have such a good collection of men again.

“I go back and forth between those two models. I don’t know if I stressed family enough when my daughter was younger, and I take responsibility for that. I wanted her to be independent and make her own choices, and I don’t think I ever said, ‘Oh, by the way, having a family is the best thing in the world.’”

Of course, even when Debbie Slevin was young, many couples waited until they were not particularly young before they got married. Not her, though. “I got married at 22 and had my first baby at 26,” she said. “I knew that many women did not have babies then, but I was so caught up in trying to fix a dysfunctional childhood that when the wave of feminism came by, I was standing on the shore, cheering everyone else on, and meanwhile baking cookies for the PTA and driving other people’s children home from work.”

Debbie Slavin: A voice for single daughters

Debbie Slavin: A voice for single daughters

Now, though, her daughter and her friends’ daughters all are in the same position — unpartnered and childless.

Some of those women mind; others revel in it. They are not interested in having children now; some would like to become mothers at some far-away time, and others would like to remain child-free.

“And some of them worked on supercareers, and then they think, ‘Oh wait. Am I missing my fertile time?’” The clock ticks.

There are some ways around that tick-tock. It is possible to buy eggs. “Eggs from women at Ivy League schools are worth more than eggs from other places,” Ms. Slevin said. (That’s a side issue in her book, though; she looked far more at women who do not have children than at those who sell their eggs.) Some people suggest that women freeze their eggs while they still are in college. “That way, they’ll have a 20-year-old’s eggs when they are 35,” Ms. Slevin said. That is a very expensive proposition, way out of reach of most college students not forward-thinking enough to be born into trust funds, so often parents fund the undertaking, one that catapults helicopter parents into an entirely more rarefied league.

In her book, Ms. Slevin talks to professionals who work with infertility, and she talks to the women themselves.

“One of the things I want people to know is that one of the factors that drove me was to try to eliminate the shame that these women feel because they are not married and do not have families of their own,” she said. “In our culture, when someone marries you” — more specifically, when a man marries a woman — “they validate you.” Women who are not partnered are constantly asked about it, questioned about it, teased about it, prodded about it, harassed about it. “They have to sit at the children’s table when the family is together; when the family travels together, they have to sleep on the cot.

“I have changed that. I have told my daughter that I will never again make her sleep on the cot.

“The important message is that these women should be valued for what they bring individually, not as part of a unit,” she concluded. “They should not have to be validated by someone else.

“My mission now is to support those women who by chance or by choice have not married and do not have their own families. Their choices are as valid as anyone else’s.”