"We've always had the mandate for motherhood — it's what women have been deemed 'for' in human history," Sandler told Here & Now . "But lately, the mommy industry is so enormous, what I call 'the ambient roar of motherhood' seems to be so deafening, that I think that women who feel like we should have transcended this pressure by now are feeling pretty stigmatized."

Author Lauren Sandler writes about the phenomenon in the Time magazine cover story, " The Childfree Life: When having it all means not having children ," where she notes that though it's becoming more common, a decision to remain child-free is anything but socially acceptable.

American birthrates are lower now than at any time in American history — including the period after the Great Depression.

I didn’t make the decision because it’s too expensive or any of these other reasons. I just — this is who I am.

Some people may feel it's too expensive to have kids, but others would rather do something else with their time, Sandler said. Many people who make a conscious decision not to have children feel strongly that it's not for them.

Among them is Barbara Brownell, a hospital administrator and avid gardener in Oakland, Calif., who has been married for almost three years. She and her husband have no plans to have kids.

"Over the first two years of our relationship, we just decided that we've got a great life — neither one of us really had a huge pull to have children, and we're happy the way it is," Brownell told Here & Now. "We have plenty of children in our lives. I think that we choose to spend our time with each other and in the garden and cooking together, rather than raising children."

Brownell does feel pressure from friends and family to have children, but she says it doesn't burden her or her husband.

"Since we've been married and we have lots of friends with kids, it's 'Oh my God you guys are going to be the best parents! You guys are going to have beautiful children. When are you going to start?'" Brownell said. "I didn't make the decision because it's too expensive or any of these other reasons. I just — this is who I am."

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