These young women are doing their part to avoid a baby bust

America’s fertility rate is collapsing. But some young women are ready to do their part to avoid a baby bust.

The average American woman currently in her peak fertility years (ages 15–49) will have 1.7 children in her lifetime, well below the replacement rate of 2.1. And more Zoomers and Millennials are choosing to forgo kids, citing the financial cost, climate change and career, among other reasons, according to polling.

It’s a trend that has demographers concerned about the economic and societal repercussions of a shrinking and aging population — a crisis currently crippling Japan and South Korea.

For Ashley Hartig, the decision to be a young and prolific mom meant resisting “girl boss” messaging.

“I didn’t feel the need to focus on a career. I just had the babies and figured it all out as I went,” Hartig, 29, told The Post.

She and her husband, Derek, an entrepreneur in the transportation industry, live in Sarasota, Florida, with their 8-year-old son, 5-year-old daughter and 15-month-old son — and they’re planning a possible fourth in the next year to give their youngest a sibling near his age.

“I’ve found a lot more joy because of my children,” she said. “I literally romanticize everything that happens every single day because everything feels so special when you’re sharing it with your own kids.”

But starting a family so early with her husband, Derek, wasn’t easy. They struggled for a couple years with multiple career changes and lack of home ownership. She says a lot of other young women are attracted to the stay-at-home lifestyle — and often reach out to her on social media to say so — but it’s so often out of reach in today’s economy.

“I think the biggest barrier is definitely financial,” Hartig said. “A lot of people want to be stay-at-home moms, and that’s almost impossible if your husband doesn’t have a super secure, high-paying job.”

A 2024 Pew survey found that, among those under 50 who say they’re unlikely to have kids, 36% cited the affordability of raising a child as the reason why.

The number one reason, however, was “they just don’t want to” (57%), followed by wanting to focus on other things (44%), concerns about the state of the world (38%), concerns about the environment (26%), lack of the right partner (24%), and simply not liking children (20%). 

Lillian, a 21-year-old who wants 10 kids one day, admits her desire to be a mother is unusual in her generation, which has fallen victim to “anti-natalist” messaging.

“Gen Z people don’t even want to be alive,” said Lillian, who works for an education non-profit and splits her time between Boston. “Everything feels really meaningless, the economic situation isn’t super great, plus there’s AI, life just doesn’t have meaning, we don’t know what the future looks like. People are very depressed, and they are just, like, anti-life.”

Hartig even hears it from peers who are critical of her choices: “People have a lot of opinions, saying you’re overpopulating the Earth, or they would never want that life, but family is all that really matters in the end, and it’s really too bad for them.”

Lillian doesn’t have a partner yet, but she knows she’d like to have a small army of children.

Her main motivation is “cultural replication.”

“There are things that I like in the world, that I want to see more of in the world, and raising kids who have those beliefs is like a vote for what kind of future you want,” explained the recent Harvard grad, who asked to withhold her last name for professional reasons.

The virtues she wants to spread: openness, intellectual curiosity, sense of adventure, resilience and adaptivity.

Lillian identifies with the pronatalist movement — a growing group, reportedly including father-of-13 Elon Musk, who believe plummeting birth rates threatens society both culturally and economically — but she says the movement doesn’t dictate her life choices.

“I’m more motivated by the idea that the kids that I have will have a shot at helping the world than I am by the birth rate going down and feeling obligated to breed more,” she said.

“The pronatalist space broadly tends to frame the issue of having children as a response to larger problems from declining birth rates, like national security, economic health, demographic support, our ability to innovate, et cetera,” Emma Waters, a family policy analyst for the Heritage Foundation, told The Post.

“Then there’s a very clear religious realm of Catholic and Protestant, Jewish and others, where there’s a very clear, faith-based, motivation here.”

Naomi Green grew up the seventh of nine children in an Orthodox Jewish family from Morristown, New Jersey — so she knows well the benefits of a big family.

“I didn’t outright love it growing up, but now as an adult, I appreciate it so much more,” Green told The Post. “I never feel alone in this world. I always have a team. I have someone that I could rely on at any moment.”

The 28-year-old Connecticut resident just gave birth to a son a week and a half ago and is also the mom of a 2-year-old daughter. She and her husband Yona, a 30-year-old engineer, plan, “God willing,” to add another three children to their family.

“I really would love to have my kids feel at school, at home, in life, wherever they are, that they’re part of this team and unit, and they’re not fighting their battles by themselves,” said Green, who is planning to return to school to become a physician’s assistant.

There is a growing difference between the number of kids that a woman wants, and the number she actually has, dubbed the “fertility gap.” According to SMU’s Bridwell Institute for Economic Freedom, the average American woman says she would be happiest with 2.5 children — yet she will most likely only have 1.7.

In her work at the Heritage Foundation, Waters, a 27-year-old mother of two looking to form a “large family” herself, researches pro-family policies to help close this gap.

She and her colleagues have honed in on reforming welfare to remove marriage penalties, changing state and federal tax codes to benefit parents and supporting couples struggling with infertility.

It might be even harder to change perception.

Madison Rae, a Manhattan mom of three who runs the clothing company Tribeca Mom’s Club, said she’s been the subject of judgement for having a larger family.

“Because I live in the city, people think having a lot of kids is crazy,” she said. “It’s mainly people who don’t live in the city, who make comments about the space or the quality of life.”

Meanwhile, she said, having big families has become a “trend” in her posh Tribeca neighborhood.

“So many people I know personally are all of a sudden having a third kid,” the 35-year-old said. “I just feel like it wasn’t a thing a couple of years ago.”

Rae, who is married to a finance professional, always wanted a big family because she grew up an only child. She now has a 7-year-old daughter, a 4-year-old son and a 5-month-old son.

“I don’t see [having kids] as like a dying thing,” Rae told The Post. When she pushes her stroller downtown, she’s regularly stopped by parents thinking of adding to their own families: “People will literally ask me on the street, like, ‘How’s three? I feel like I want to do it.’”