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The ticking clock that has been nagging Lauren Rankin is not a biological one. It’s one she and her boyfriend Jason created. They’ve spent nearly five years together in a loving, committed relationship, but they set a deadline of March to decide whether or not to break up.

The only thing driving them apart is the question of having kids.

Conventional wisdom would cast this as a baby-hungry woman up against a skittish man, but Lauren’s predicament is exactly the opposite.

“We’ve both known from the beginning of our relationship that he’s always wanted kids, always wanted a family, and I’ve always been ambivalent as hell about it,” she said. She’s wary of the responsibility and commitment of having a child. But life events have forced the issue. She’s 29 and he’s 34, and he wants to have children before he gets to 40. More pressing is that they live in Asbury Park — a four-hour round trip every day. Jason is willing to move somewhere more convenient, but only if they can agree that children are in the future. “That’s the ultimatum,” she said.

They nearly broke up over the dilemma last summer, but it’s hard to stay apart: After all, they love each other. “He wants me to have what I want, and I want him to have what he wants,” she said. “But that might mean doing those things not together, which is really sad.”

Lauren is part of a growing cohort of women: those in their late 20s and early 30s who aren’t sure about — or are decidedly against — becoming mothers. In a nationally representative survey of single, childless people in 2011, more men than women said they wanted kids. (On the other hand, more women reported seeking independence in their relationships, personal space, interests, and hobbies.) A different poll from 2013 echoed those findings, with more than 80 percent of men saying they’d always wanted to be a father or at least thought they would be someday. Just 70 percent of women felt the same.

Today’s young women have more of a choice about their fertility than their grandmothers did, and perhaps clearer eyes about the challenges of child-rearing than their mothers. For these women’s grandparents, having children wasn’t a question, it was a given. And they had lots of them, spawning the baby-boom generation: The birth rate reached 122.7 children born per 1,000 women of childbearing age in 1957. Boomers themselves had more of a choice thanks to the widespread adoption of the pill and changing social expectations brought on by the women’s liberation movement, and the birth rate sagged, then stabilized.

But while the hippie generation may have dreamed of utopian, egalitarian relationships, the reality was often different. “What I’ve seen in my generation of women is a number who had fewer children than they wanted,” said historian and sociologist Stephanie Coontz, who studies women and family structure and is a boomer herself. “They had one instead of two or three … and said, ‘I can’t have another, it’ll destroy my career.’” Fathers started doing more housework but didn’t really increase the time they spent on child care, while mothers kept doing the vast majority. The divorce rate spiked in the 1970s.

This generation hasn’t solved the problems. But young women may be more aware of them. “The younger generation of women is even better integrated into the workforce and feels like sometimes they’re forced to choose between having a meaningful career and having kids at all,” Coontz noted.

The majority of today’s young people of both genders seek an egalitarian split in work and family responsibilities. But even if both partners want it, women are aware that they probably won’t get it. Achieving equality in the home is easier said than done: In a 2011 survey of fathers, 65 percent said they believed both parents should spend an equal amount of time on child-rearing. But when asked about their realities, 64 percent said their wives provided more care. “I think before you have kids it’s a lot easier for men to imagine combining work and family,” Coontz said. “There’s work involved with having kids that women can anticipate better than men. We saw our moms do it.”

The work of raising children also comes with virtually no support. American mothers aren’t guaranteed paid maternity leave or paid sick leave and are offered virtually no help in affording the exorbitant cost of child care. They also face widespread discrimination and a hit to their incomes just for becoming a mom.

The women interviewed for this story didn’t always think their male partners would let them down. But they were all acutely aware of how having a baby would significantly rearrange all of the pieces of their lives, many of which they worked hard to put in place.

“I’m within the early 30s female realm of not wanting to rule anything out, but also becoming increasingly aware of how intensely it changes one’s life,” Jennifer said. She and her boyfriend of more than ten years have not rushed to marry or have children, but he’s certain he wants the latter someday. Jennifer says she loves her friends’ kids and sees how rich their lives have become. But she’s acutely aware of the trade-offs. She likes “having a quiet Sunday [to] read at the pace I choose and to prepare meals for our adult palates,” she said. And while her boyfriend sees the work of child-rearing as a meaningful benefit, Jennifer worries it will consume her. “I have a strong instinct to be the caretaker for so much, even though I know that [my boyfriend] is certainly wanting to be in it,” she said.

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Plus, there’s the inherent chaos a child brings into anyone’s life. “I guess I’ve always been someone who wanted to try and map out life stages before arriving at them,” she explained. “But of course I realize I can’t exactly plan out what it’s like to have kids before I have them.”

Lynne (not her real name) wrestled with the question of having children for years, knowing how much her husband wanted them and hoping that a maternal instinct would eventually appear. “Women talk about this thing that kicks in, how all of a sudden you hit a certain age or certain time in your life and then you get it,” she said. She and her husband talked about children before they got married, but put the idea in the “someday” category.

But then they went apartment hunting four years ago and ended up with a three-bedroom unit. “We were putting the pieces in place just in case,” she said. The fear that they wouldn’t end up on the same page, however, kept them from discussing whether they were actually going to have a kid. “I was trying really hard to convince myself that I wanted one,” she said.

Then she had what she called a “pregnancy scare.” “The fact that this was the term that came to mind is very telling,” she said. “That was when I knew that I didn’t want one.” There are personal reasons for why she doesn’t want to have a baby: difficult parents and a tough childhood, worries that the mental illness that runs in the family would be passed on. But she was also dogged by the fear that she would have to give up her whole life. “I just remember riding the subway, going to work, walking around unencumbered, and thinking, I’m never going to be able to do this again.”

She eventually told her husband about her missed period (which later turned out to be a false alarm), and he was overjoyed. But she voiced her concerns. “I was like, ‘’You know, you travel four months out of the year. I will have to give up my entire life if I’m going to have a kid.’” She had already thought through the disruption, but the notion that his life would change was entirely new. “Even in a progressive, liberal, feminist household like ours, there was still that idea that the woman will stay home and the guy will keep working … or that a man’s work isn’t going to be compromised.” At one point, she asked if he would consider quitting his job to be a stay-at-home father given how much he wanted a baby. “That just wasn’t the plan he had in mind,” she said.

“I just want to have a life and enjoy it and determine, as much as anyone can, which way it goes,” she said. “I want to be able to read a book at the café for a couple of hours if that’s what I feel like doing.”

That question of losing autonomy haunts single women as well. Courtney Y. feels totally ambivalent about whether she eventually wants children. Part of her concern is what pieces of her life she might have to say good-bye to, weighing “what things I would gain from having a child, but also what I would give up,” she said. She splits her time between New York City and her home state of Louisiana and enjoys “being completely independent.”

As an African-American woman, her race also plays a role. “To be honest, I’m terrified of having a son right now,” she said, pointing to the #BlackLivesMatter movement and the police killings that sparked it.

For Lauren, the hardest part is committing to something that will mean so much upheaval. “It’s the constant responsibility that really scares me. It’s the forever commitment,” she said. Her work is in reproductive rights, which informs her views. “I know the importance and the life-changing nature of having a child,” she said. “I see that firsthand.”

She also thinks about what it would do to her career and life. “I definitely think it would affect a lot of things,” she said. Would her full-time job accommodate a child? Does it offer maternity leave? Finances come into play. “We have good jobs and make decent money … but we barely have enough living outside of New York City,” she said.

Women who can’t say for sure that they want children don’t just have to contend with potential partners who do, but with a society that may not yet understand them. “It feels strange for me to be the one who’s putting on the breaks,” Lauren said. Friends understand if she’s putting off kids; it’s harder for them to understand possibly not wanting them at all. “There’s no set response to that,” she said.

Lynne has really struggled with this challenge, particularly after she knew she didn’t want children. “I always thought men didn’t really want kids, that it’s women who want them,” she said. “I found it to be completely the opposite.” Despite his desire for a baby, her husband has committed to staying with her, even if that means never having one. But that doesn’t shield them from painful and awkward reminders. “At our age, when you meet new people, they say, ‘Oh, do you have kids?’ And you say no, so the next thing they say is, ‘Do you want them?’” she recounted. “It’s the most personal question, the most painful question.”

Lauren has to answer that question, and soon. “I keep waiting for that mom gene to kick in, I keep wanting to just wake up and go, ‘I want a baby today,’” she said. She’s also not willing to tell Jason she could want one in the future if she doesn’t know for sure. But she hasn’t had a moment of clarity yet. “It’s like we’re in the Choose Your Own Adventure book, and I have to pick an adventure,” she said. “I wish I could know which one I want to do, but I don’t know.”