I have one child. Just one, single child, yet it often takes me a solid hour to get out of the house. When I’ve finally shut the door behind us, I wonder how people with a bunch of kids do it. Then again, sometimes I’ll see a very chill parent getting off the bus while baby-wearing, pushing a stroller and simultaneously directing a small gaggle of school-age kids and think, She looks way less stressed than I feel. According to a survey of more than 7,000 mothers, she probably is.

A survey by TODAY found moms of four or more kids report lower stress levels than moms of fewer kids, but they have to get over a hurdle to get there. The survey found moms of three stress more than those of us with just one or two kids, but once you get beyond three, it’s smooth(er) sailing.

Perhaps it’s that moms of large families learn to better cope with stress and let more things go. Or perhaps women who have an easier time dealing with stress are more likely to want more kids. But, surprisingly, four kids seems to be the magic number when stress lowers for mothers.

This isn’t news to psychotherapist and author Kelley Kitley . A mom of four herself, Kitley feels that moms of large families are often unfairly perceived as more stressed than they actually are. “So many women with large families get a bad rap,” says Kitley.

According to Kitley (whose children are 11, nine, seven and five) large families mean parents reap the stress-relieving benefits of teamwork and sibling bonding. “They encourage each other, hold each other accountable, help out more to lighten the load at home, and the kids entertain each other,” Kitley explains. “Having more than three kids certainly hasn’t been a breeze—the laundry in and of itself is overwhelming—but overall, it’s a lot of fun.”

There is some scientific support for the idea that it’s not just the parents in larger households who are less stressed, but the kids, too.

A 2016 study of Norwegian kids found those who grow up in large families have fewer mental problems, suggesting the households in general are less stressed. The more siblings a kid has and and the closer in age they are, the more pronounced the stress-reducing effects, say the researchers.

Of course, to get to the stress-protecting factor for kids and adults as indicated in the survey, you would have to get beyond the hurdle of having three kids and moving on to four, which isn’t something some parents (like me) have any interest in doing. According to some experts, three can be as hard as the survey suggests.

“For some families, three is tough, because I’ve interviewed parents that said they had it under control with two—man on man defense—[but] with 3 kids, they were now playing zone defense, and it was trickier,” says Dr. Jennifer Wider, author of The New Mom’s Survival Guide and Got Teens.

Parental stress levels depend more on the attitudes in the family than the exact number of kids, according to Wider, but in her research, the overarching sentiment was that moms felt more confident and less stressed with subsequent children.

That’s a phenomenon that’s been dubbed “the Duggar effect,” implying that once you get passed a certain number of kids, the stress levels don’t increase with subsequent children.

A 2000 study out of Sweden suggests the opposite is true, and that parental stress levels actually do increase with the number of children in the home. The study contradicts the survey, and so do some parenting experts.

“I don’t agree with these survey results,” says Eirene Heidelberger, the founder of GIT Mom , a parenting coaching service that helps stressed out moms “get it together.”

The sheer logistics of organizing a large family can be very stressful, says Heidelberger, a mom of three boys herself, and parents can’t count on older kids to make things easier around the house. “Children do not raise themselves nor should siblings be expected to raise their younger siblings,” adds Heidelberger. “It takes a lot of energy, mental resources and money to raise a large family to ensure each child feels loved, special and tended to.”

Indeed, parenting requires a lot of us. A recent study found parents in general are more stressed than people without kids , but it’s not our kids that are stressing us out, it’s things like lack of paid leave, affordable childcare and sick time.

So in a world where those things are hard to come by, how many kids is the right number for a less stressful life? It’s whatever number you want and think you can handle, says Kitley (and your instincts).

She doesn’t want to see moms of one shamed for not giving their child a sibling any more than she wants mothers with large families to be criticized for their choices. She just wants moms to try and see the joy of parenting, because that will reduce our stress, no matter how many children we’re leaving the house with. “The more we can enjoy it and embrace it, more than feeling like [parenting] is this daunting task, the better time we’ll have doing it,” she says.