Maternity leave is the mother of invention.

So say the women who have launched startups, written books and opened art galleries while they were tending to their newborns.

“When else do you ever have six weeks (or however long your leave is) when you’re not grinding away in college, you’re not in a job, when you are literally focused on your family and those basic things you need?” Julie Lohre, who became an online personal trainer while on maternity leave, told Moneyish. “It does spark creativity in women, thinking outside the box of, ‘What else can I be doing? Is this my mission in life?’”

Welcome to the power maternity leave.

A recent survey of more than 2,000 British mothers found that 1 in 6 planned to start a business during their maternity leave. Almost 1 in 5 (18%) wanted to practice a new hobby, and 12% wanted to learn a new language.

While new moms are recovering from the physical and emotional wringer that bringing a tiny human into the world entails, many are also humming with creativity. Studies have shown that the brain becomes more inventive during pregnancy by working to meet an infant’s every need. One lab found rats who became new moms were smarter, braver and more resourceful, for instance, than those that had never had babies.

Read also: Why women are way more likely than men to have a side-hustle

And no one multitasks like a mom. Former CIA analyst Karen Cleveland wrote her new espionage thriller “Need to Know,” which hit shelves Tuesday, while she was on maternity leave with her second child.

“My routine was pretty much to fit in writing whenever I could,” she told the New York Post. “I’d be at playgrounds with them and I’d be plotting scenes in my head, then would write everything out at night.”

Almost 600 businesses owned by women are added to the U.S. workforce every day, and many of these were dreamed up and fine-tuned between breastfeeding and diaper changes. Some dabble in multilevel marketing (MLM) side hustles like Rodan and Fields or Lularoe. And some finally dust off that passion project or go into business for themselves.

Moneyish spoke with the women who used their maternity leave to launch some amazing startup projects. Here are four of their stories.

The Teething Bead Designer

Andrea Chinalai was already cutting her teeth on jewelry design, but her digital advertising career (including working for Rachel Zoe’s “Zoe Report”) didn’t let her devote enough time to her fledgling accessories site.

Momtrepreneur Andrea Chinalai designed chic teething jewelry line Anjie & Ash while on maternity leave after grappling with her infant son chewing and tugging her necklaces. (Andrea Chinalai)

She got back to designing pieces during her maternity leave two years ago. And that’s when, like many new moms, she found her son Ash was obsessed with trying to put her necklaces in his mouth – especially once he started teething.

“I realized quickly that I couldn’t wear regular jewelry because he would pull it off, tug on it, break it,” she said, “and I thought, ‘There has to be some other jewelry out there that’s safe enough for a baby to put in his mouth.’”

Her research dug up teething jewelry pieces that she didn’t find fashionable. “Everything looked like a toy,” she said. “Or the clasp would get stuck, so when my son would tug on a necklace, it hurt.”

So Chinalai and her husband spent a year working with a magnet manufacturer to develop a magnetic clasp (patent pending) that will release when baby tugs too hard. She also began taking jewelry-making lessons and soldering classes to master her craft, and ultimately designed a collection of necklaces and bracelets made from non-toxic silicone, beech wood and stainless steel. She used her cut from selling their Brooklyn condo to move to Miller Place, Long Island, to start up Anjie + Ash, which just launched in December with pieces ranging from a college fund-friendly $10 to $35.

Momtrepreneur Andrea Chinalai designed chic teething jewelry line Anjie & Ash while on maternity leave after grappling with her infant son chewing and tugging her necklaces. (Andrea Chinalai)

“It’s been a whirlwind,” she said, noting they’ve already had 2,000 visitors to the site, and landed in the top 25% of Shopify’s ecommerce sites during their launch period.

“I’ve come up with the campaigns for big companies, big advertisers, and the creative juices just never stopped flowing … and becoming engrossed in closing a deal and feeling that success and giving yourself that pat on the back, that never left me,” she said. “So after putting two years of time and effort into this, if people like it, that will be the greatest success yet.”

Speaking of passion projects, Chinalai has another baby on the way – and she’s already got a new project to work on when she begins her second maternity leave this spring.

“I don’t want to say too much yet, but it’s essentially a mini diaper bag,” she hinted. “It’s funny – you don’t think that when you have a kid, that will be the time to take these risks – but the most motivated I felt to take a risk, ever, came after having a child.”

The Self-Published Cookbook Author

This indie publisher has penned a vampire novel and a couple of bilingual Chinese/English children’s books. But trying to wean a fussy baby two years ago became the recipe for “Feeding the Kraken,” her cookbook for fellow frustrated moms.

Momtrepreneur Jean “JF” Garrand wrote “Feeding the Kraken” during her maternity leave. (JF Garrand)

“I simply didn’t know what to feed my child when he started to eat solid foods,” Jean “JF” Garrand, 35, told Moneyish. He was a carb fiend, but wouldn’t touch fruits or vegetables. “I didn’t know what to do with him. I was just trying to keep him alive!” she said.

When the Toronto mother and president of Dark Helix Press started a Kickstarter to crowdsource the cash to test recipes before self-publishing and distributing her toddler cookbook, raising about $400 Canadian ($340 U.S.), she also received countless tips and tricks from other moms looking for resourceful ways to get picky kids to eat.

“One lady said her daughter was really into those Yoplait drinks, so she used to keep the containers and mix milk and yogurt into them, and give the to her daughter to drink,” she laughed. The 50 recipes include overnight chia seed chocolate pudding, and meat-and-veggie “meatloaf muffins” as hearty way to sneak in diced carrots, zucchini and bell peppers.

Momtrepreneur Jean “JF” Garrand wrote “Feeding the Kraken” during her maternity leave. (JF Garrand)

The cookbook also gave her the opportunity to hone her graphics skills, she she opted to illustrate it herself instead of hiring a graphic designer. “My job involves a lot of reporting and working in infrastructure, which is not really a creative thing,” she said. “I really loved doing the graphic art on the side. It was fun, almost like making a scrapbook, but digitally.”

This has always been a project of passion over profit for her. “I never cared about how much money came out of it,” said Garrand. In fact, she initially offered the $3.99 “Feeding the Kraken” as a free download for many parents because “everyone is struggling,” and admits she’s sold less than 100 books – basically, just recouping her expenses.

No, this is about leaving a legacy behind. Garrand wishes her late father, a chef whom she dedicated her toddler cookbook to, had written more sothat she could get “a glimpse into some of the things he liked. He was a very quiet man,” she said. “So for me, writing is leaving a little piece of me behind for my son.”

The Gallery Owner

Noemi Camara was a successful writer and editor for Scholastic and Houghton Mifflin Harcourt in London, commuting an hour each way from her Brighton home. She tried freelancing remotely after her first baby was born six years ago, but found herself mommy-tracked.

Momtrepreneur Noemi Camara left publishing in London to open the Whistleblower Gallery in Brighton. (Noemi Camara)

“All of the good projects ended up on somebody’s else’s desk,” said Camara, 45. “I felt that I was not working out for them in the way that I used to — until one day, I realized that they were the ones who were not working out for me. I was the one who had to go out and find another way.”

Having her second baby two years ago was the impetus for a fresh start. She decided to open an art gallery in Brighton because she realized locals were looking for an art scene closer to home than London. Plus, she had industry know-how and connections thanks to her husband also owning a gallery.

“I was up in the middle of the night breastfeeding my baby, and writing business plans with my other hand,” she said. “I had a lot more time to think than I had had before, when I was working.”

And she was inspired by the other moms that she met in parks and cafes, who were also hustling. “My God, everyone was very entrepreneurial,” she said. “They weren’t just baking cookies for bake sales – they were selling them at health food stores. After all, they all had careers to begin with, for the most part, and they were all very used to the professional world.”

Camara opened the Whistleblower Gallery in a converted carriage house two months ago, which displays British Contemporary works by up-and-coming and well-established artists, such as Radiohead’s album cover illustrator Stanley Donwood. She bankrolled it by selling three Banksy pieces from her private collection for more than $35,000.

Momtrepreneur Noemi Camara left publishing in London to open the Whistleblower Gallery in Brighton. (Noemi Camara)

“It was really hard to let go of them,” she admitted, “but I had no other way of starting. The bank said no … and I was too old to go to my parents. I wanted to do this on my own.”

The gallery has already turned a profit, though, and four months earlier than she had expected. They’ve hosted three shows already, with three more planned in the coming months, and they have hosting biweekly dinner parties and movie nights to build word-of-mouth.

“I’m an older mom, so I’ve already had my career. Now I want to focus on the kids,” she said. “But I can’t afford to be a stay-at-home mom. And I do need to have my own space and my own adult world, and to be financially independent. I’ve created a situation that works for me.”

The Fitness Pioneer

Fifteen years before #fitmom influencers became a social media revenue stream worth hundreds of thousands of dollars per post, Julie Lohre began searching the web for whatever she could find about getting in shape after giving birth to her son.

Momtrepreneur Julie Lohre began winning fitness competitions during her maternity leave, and became a successful online personal trainer. (Julie Lohre)

“Between diaper changes and baby feedings, I began studying everything I could about health and fitness in addition to getting my body back into shape,” said Lohre, 43, from northern Kentucky. She had been a Procter & Gamble research engineer for Tampax and Always feminine products, and as the start of her maternity leave approached, she was already doubting whether she would return to working there just six weeks after giving birth.

“I sat down with a pencil and paper, and went through how much I was making, how much childcare cost, and how could I make up the difference, what could I do to still support my family … but also feed this need that I had for helping women and having my own identity along with my motherhood?” she said.

She’d always been athletic, and fell back on exercise. “Workout time become my own personal ‘me’ time … something of a mental health break that allowed me to come back to my baby an hour later energized and re-focused,” she said. She read anatomy and physiology textbooks, and joined a gym with a trusted daycare center where she felt safe dropping off her son while she dropped the baby weight.

She entered a local fitness competition, and won it five months after her son was born, which launched her on-camera career in physical contests that included the National Fitness Competition, becoming an IFBB Fitness & Figure Pro and eventually competing on “America Ninja Warrior” once she turned pro in 2004. Her largest prize package topped $12,000.

Momtrepreneur Julie Lohre began winning fitness competitions during her maternity leave, and became a successful online personal trainer. (Julie Lohre)

She also got certified as both a personal trainer and a nutrition specialist, and began coaching some other mothers at her local gym. And it was those 1-on-1s that truly flexed her entrepreneurial muscles.

“I quickly realized that I didn’t want to be tied down to someone else’s schedule,” she said – which being a trainer at a gym required. “And a lot of other women felt the same way about their workouts; they didn’t want to depend on someone else’s schedule. So I started coming up with workouts and training plans a woman could do on her own, whether she was at her house or at her gym, without being constrained to someone else’s timing.”

She and her husband have built her brand from a self-published website into JulieLohre.com and her supplement store FITBODY.com over the last 15 years, which she said saw half a million in sales last year from her $495 8-week training plans and her $59 ebooks. “The profits far exceed anything that I could have earned in my former career,” Lohre said, noting she’s earning three times as much. “I just want to educate other women around the world. I want them to feel great and to look great.”