From an early age, she knew deep down that she didn't want children. Maybe it stemmed from seeing her mother sacrifice her dream of becoming a flight attendant and work three jobs to raise two kids alone. Or maybe it was that other endeavors interested her more.

"I'm always looking forward to the next thing," said Volek, who works in local government in San Francisco. "Being a parent was never one of them."

Still, the idea of not having children seemed taboo, so she didn't dwell on it much. It wasn't until a few years ago when she started getting serious with her partner that she really reckoned with her feelings. By the time she and her husband got married last November, they had reached a conclusion: They didn't want kids.

Volek is now 37, and doesn't see herself changing her mind.

Not having children gives her a sense of freedom that her friends who are parents don't have. Now that they're vaccinated, she and her husband have been able to eat at restaurants, attend concerts and travel without worrying about risking their child's safety.

They can work toward retiring early, a goal that would be otherwise unattainable in a city as expensive as theirs. And in their day-to-day life, they have plenty of time for themselves.

Volek is one of a growing number of women in the US who are opting not to have children -- part of a trend that has been underway for more than a decade.

Since 2007, the nation's birth rate had been declining about 2% each year on average. Despite early speculation about a pandemic baby boom, the coronavirus crisis accelerated the decline even further, with births falling by 4% last year.

It was the largest annual decline in the number of births since 1973, according to the Centers for Disease Control and Prevention.

Demographers point to a number of factors driving this phenomenon: economic insecurity, political uncertainty, shifting gender norms and a lessening stigma around the choice to remain child-free. Though the pandemic laid bare just how little support families in the US receive from the government when it comes to childcare and other obligations, some women had already made up their minds before then.

Here are some reasons why some women are choosing not to have kids.

They don't want the responsibility

Cecilia Sanders, a 32-year-old project manager in Chicago, was sure early on that she didn't want children. It felt like too great of a responsibility, and the idea of pregnancy scared her.

Still, she says she felt pressured to feel differently, as though she would be disappointing others by not having kids. For about a year, she tried to force herself to change her mind, talking to friends who were parents about their experiences and how they made time for themselves.

As it turns out, her friends often didn't have time for themselves. Their kids, they said, came first.

Sanders realized that sacrificing her own needs to fulfill her duty as a parent would be especially taxing for her. She grapples with anxiety and depression, and when those conditions flare up, even taking care of herself becomes challenging.

The thought of raising children while still preserving her mental health seemed near impossible.

"After a year of really thinking about it, I was like, 'No. If I do this, I'm lying to myself,'" she said.

They fear a lack of support

For some, how the US treats mothers is reason enough not to have children.

Amy Blackstone, a sociologist at the University of Maine and author of "Childfree by Choice: The Movement Redefining Family and Creating a New Age of Independence," says the lack of family-friendly policies in the US is one explanation behind the declining birth rate in recent years -- something that the pandemic made even more clear.

Over the last year, parents have had to continue working, often without childcare or while having to help their children learn remotely. The situation has left people stressed and depleted, and perhaps more likely to delay or reconsider having more children.

"The pandemic has really revealed to us how poorly we support parents in the US," Blackstone said. "We've come to see the truth that we've always known but never speak out loud, which is that parenting is really hard. And we don't really support parents in that role."

That was certainly a consideration for Yana Grant, a 24-year-old in Tulsa, Oklahoma, who decided last year to not have children. The US offers no national, paid parental leave program. Child care can be expensive or hard to find. And women are still more likely to shoulder the brunt of parenting responsibilities and household tasks.

"As soon as you find out that you're pregnant, you have to be a mother first and then a woman," Grant said. "Men get to be men and then a father, it seems like."

As a Black woman, Grant has other things to worry about, too. Black women are more likely than women of any other race to die of pregnancy-related problems. They're also more likely to have their concerns dismissed, their pain untreated and their experiences disbelieved.

For Grant, those worries are rooted in reality. A few years ago, she felt her heart beating fast and her throat swelling, and went to see a medical professional. She says the doctor told her to stay hydrated and sent her home without checking her thyroid. When she saw another physician for the same symptoms about a year later, she was diagnosed with Graves' disease, an autoimmune disorder that causes an overactive thyroid.

If she got pregnant and something were to go wrong, Grant fears her symptoms and complaints might be similarly dismissed.

"I feel like as a Black woman, you don't have a lot that is yours," she said. "And so me keeping that part of me is the only thing I know I have control of. [I can] say that I made that conscious decision to save myself because more than likely, no one else is going to do it."

They like their life as it is

While Jordan Levey focused on law school and building her career, she assumed a "maternal instinct" would eventually kick in. Once she found a partner, she figured, they'd settle down and perhaps decide to have kids.

Now that she's 35 and has been married for four years, Levey says she and her husband have realized they prefer their current lifestyle. They own a condo and are loving parents to their dog. And though they both earn a comfortable living, they'd rather spend their money on the things they love.

"We are really happy in our life. We love to travel, we love to cook, we both really value our alone time and that self-care," she said. "I think we would be perfectly fine parents -- I just don't think we would enjoy it."

For Sanders, not having kids allows her time to pursue all of her interests: writing, playing guitar, hiking, traveling and rescuing animals. It also means that she can focus more on her career, which for her is "the most important thing."

"I definitely feel I probably wouldn't be as far in my career as I am now and [I wouldn't be] able to just live my normal life and pursue my hobbies and passions," Sanders said. "I wouldn't be living my fullest life."

That women like Levey and Sanders feel empowered to choose a lifestyle without children is significant, says Blackstone.

In the past, women who could have been inclined to remain childfree might have given birth anyway because that is what society expected from them. In recent decades, though, those norms and attitudes have changed.

"We're having more conversations about the reality that parenthood is an option, not something that everybody has to do," she said.

But they're still judged for their choice

It's perhaps more socially acceptable than ever for women not to have children. Even so, women who choose to remain child-free say they still feel like they constantly have to explain their choices to others.

They've been called selfish, accused of hating kids and told they'll regret their decision later in life when they find themselves alone.

Volek says she feels child-free people like herself are judged as superficial or not having grasped the enormity of the decision they're making, when that couldn't be further from the truth.

"People who choose to be child-free think a lot about it -- I would argue even more than people who have children," she added.

The assumption that child-free women don't care about children simply isn't true either, some say. Volek loves playing with her friends' kids. Levey enjoys spending time with her niece and nephew.

Grant is in a relationship with a man who has a son and is perfectly happy to hang out with the youngster one on one.

"I will ask if he wants to go see 'Boss Baby 2.' I will take him to some of the Smithsonians," said the Oklahoma resident, who plans to move with her partner to Washington, DC. "But that's as far as I will go."

Blackstone, who has interviewed countless people about their decision to remain child-free, says that the people she's spoken to acknowledge that it's possible they may one day regret making the choice that they have.

But she said they'd rather not have kids and regret it later than have kids and regret it later.

CNN