We do it to ourselves.

18-year-old mother has cosmetic surgery "to feel young again"

Ms Young, who has a two-year-old daughter, said she felt old and hoped to reclaim her youth and regain confidence.

The surgeries would cost $13,000. Ms Young has borrowed the money from a friend.

"After the birth of my daughter, my body never went back to the way it was before," Ms Young said.
"I'm having this surgery so that I can feel my age again," she said.

Ms  Young's surgeries will include a tummy tuck, breast lift, & "vaginal rejuvenation."  (Do yourself a favor: do not Google "cosmetic gynecology."  Ever.

Some neo-Pagan belief systems recognize a threefold aspect to womanhood: maiden, mother, and crone.  Each phase is to be celebrated for what it is, both by men and women, and embraced as the way it should be.  Motherhood is not explicitly celebrated in Christianity, at least in my experience, apart from the Blessed Mother, and it wouldn't surprise me if, these days, we expected Mother Mary to not have a single stretch mark.

There is a definite cultural bias toward the Maiden over the Mother (much less the Crone).  I am sure there are some out there who would blame men for this, but I don't think it's accurate.

Reading this article on Jezebel, where I first came across it, one commenter said "However, the pressure that women feel these days to get back their 'pre-pregnancy' body is intense, and totally unnecessary. The constant pre-baby-body stories in tabloids are misleading and almost always feature photoshopped images. Getting a concave 'bikini body' stomach is often seen as more important that having a healthy pregnancy and healthy family. It shouldn't be that way. Post-pregnancy bodies should be seen for the wonders they are."

I see where she's coming from, but I don't really understand it.  Tabloids have been aimed at women for as long as I can recall; we're the primary consumers of them, after all.  I've noted here before the attitude women's magazines in general have toward women's bodies.

The body of a woman who has given birth even once is not the same as the body of a woman who has never had children.  Though age alone is undoubtedly enough to change a woman's body, pregnancy and childbirth do more, and more obviously, than age alone will.  Pregnancy widens a woman's hips (this will happen even with a c-section, as the pelvis inevitably softens and spreads to accommodate childbirth), darkens her nipples, changes the size and firmness of her breasts, etc.  That post-pregnancy pooch is a real thing, especially for those of us with surgical births in our past, and pregnancy has even been known to change the texture of a woman's hair (mine just grows a lot faster, but I've heard stories of women whose hair went from curly to straight or vice versa).  Sometimes childbirth leaves us with literal scars.

The thing is, I've never come across a man who gave a damn.  (Note I say man and not boy--it's a definite matter of maturity.)  I don't doubt that some do, but that's a failing of the individual, not the gender.  Granted, my husband has no experience of my pre-children body, but even my ex-husband, for all his other shortcomings, never had a problem with it.  I haven't heard many complaints from other women that their husbands are suddenly turned off by their bodies after they have kids.  (I actually can't recall ever hearing it, but it could have happened.)  I've heard the saying that men fall in love with women they find attractive, and true though that may be there's a corollary that once they have, they find that woman they love attractive as she changes.

Still, the desire to "get my body back" is a common one.  Tummy tucks--abdominoplasty, I think is the technical term--seem to be pretty common, and to be honest I can understand that.  It's mainly a matter of getting rid of excess skin, which is something that just won't go away on its own and can really affect the way clothes fit you.

Overall, though, the desire to return to a pre-baby body is something that women want from other women, not that men want from them.  Most things are.  Women are the ones most concerned with the size and shape of their breasts, for example.  Men?  As long as they think they might get to touch it, they're usually happy.

Maybe we should take that as a cue.  There's pretty much always at least one man who wants to see each of us nekkid.  That's a good thing.