Medical News

Pregnancy Can Change Your Shoe Size Forever

One night in July, a few weeks after my son was born, I lay awake, desperately scrolling through photos of injured feet. The mounting pain from an ingrown toenail in my right foot had become excruciating, and the internet promised to help. I could no longer deny the fact that the exorbitantly expensive Hoka sneakers I’d bought just months before—to prevent pregnancy-related foot pain—had become too small. To my horror, my feet had grown half a size. Permanently.

Pregnancy books had informed me about the less rosy aspects of new motherhood, such as shedding hair (the baby’s and mine) and uncontrollable crying (the baby’s and mine). I was even prepared for my feet to temporarily swell through the trimesters. But no one told me they might stay that way. Unlike the rest of my body, my feet did not revert to their original size 9.5 after birth. Five months later, I am now the disgruntled guardian of a large infant—and even larger feet.

Mom Feet is not a niche condition. Studies have found that anywhere from 44 to 61 percent of new moms experience lasting foot growth, and many seem to be surprised when it happens, just as I was. “Why does no one talk about the PERMANENT foot size changes after pregnancy?” one Reddit user lamented. My thoughts exactly.

Temporary swelling in the feet (and hands) is a normal part of pregnancy, particularly in the third trimester. Extra fluid in the body tends to pool in “gravity-dependent areas,” causing ankles and toes to become noticeably puffy, Silvana Ribaudo, an ob-gyn at Columbia University Irving Medical Center, told me. This is not the same thing as Mom Feet, which I learned the hard way by wearing my Hokas long after they’d started to pinch.

Foot swelling subsides after a person gives birth, but structural changes in the foot do not. Permanent foot growth, like most other disconcerting bodily changes that happen during pregnancy, can be attributed to hormones—in this case, one aptly named relaxin. It relaxes body tissue so that a growing baby can unfurl, then squiggle out. These changes are especially welcome in the pelvic region. In the feet, not so much.

If a pre-pregnancy foot is like an ice-cream sandwich straight out of the freezer—sturdy, structured—one relaxed by relaxin is a sandwich left out in the sun. The hormone causes the ligaments and tendons in the foot and ankle to lose their rigidity and strength, so the foot tends to spread out, Alexandra Black, a podiatrist at Foot and Ankle Specialists of Central Ohio who co-authored a recent review of pregnancy-related foot changes, told me. Throwing pregnancy weight on them only compounds the problems. “It leads to more of a flatter foot, a wider foot, and a longer foot,” Black said. According to the few small studies on the topic, pregnant feet, on average, go up by roughly half a shoe size and lengthen by 0.4 inches. It is a small consolation that this effect is most pronounced during first pregnancies, meaning that feet won’t grow indefinitely along with one’s brood.

It would have been nice to learn this before I bought my Hokas, of course. Had I known better, I probably wouldn’t have purchased so many Nike Air Maxes in recent years, or suggested to my husband that we buy matching white Jordans at an outlet mall during our honeymoon. Now those beloved shoes, along with the Hokas, have been banished to storage, while I’ve had to pay up for new winter boots, high heels, and sandals.

Having to buy new shoes is expensive but admittedly kind of fun. Other consequences of Mom Feet are not. Footwear is annoying, because even a small shift in foot size can lead to shoes that don’t fit. And the collapse of the arch in your feet can be especially painful. Mine used to be graceful, like the arc of a leaping gazelle. Now the gazelle has face-planted. That’s because a tendon on the inside of the ankle, which normally acts like a bungee cable stabilizing the arch, goes slack during pregnancy. Lengthening and flattening this tendon can cause “a flat-foot deformity,” Black said, “and it’s kind of hard to reverse that.” Flat feet can cause the knee and tibia to over-rotate, throwing the bones and muscles involved in walking and standing into disarray—a “major contributor to pain” in pregnancy, one review noted. Conditions such as painful heels caused by plantar fasciitis, leg cramps, bunions, and nail issues are all linked to Mom Feet.

Had I known about Mom Feet, I might have been better prepared for it. Some pregnant people and new moms find it helpful to use compression stockings to reduce swelling and get orthotics for extra arch support, Black said. Unfortunately, none of my doctors (who I should note were very good) warned me about it. Ditto for any pregnancy book I read, such as What to Expect When You’re Expecting, which said only that swelling of the feet was “normal” and “temporary.” I am far from the only person who has been caught off guard by newly big feet. Mystified mothers abound on pregnancy forums; colleagues told me they were “not warned” and “had no idea this was A Thing.”

Perhaps the reason it is commonly overlooked is that, in the grand scheme of things that mothers-to-be have to deal with, such as gestational diabetes and life-threatening spikes in blood pressure, foot pain is relatively inconsequential. Because foot-size changes “are not concerning for the well-being of mom or baby,” they might not be deemed worthy of discussion, Leena Nathan, an ob-gyn at UCLA Health–Westlake Village, told me.

But perhaps Mom Feet isn’t talked about because many things about it are still unknown. Not everyone experiences pain, and although permanent changes are well documented, feet might still possibly revert to their original size eventually. “It can take several years,” Ribaudo said, but “sometimes it never goes back.”According to Nathan, it isn’t well understood why some people experience changes in foot size and others don’t. Even the true prevalence of this condition isn’t known for certain, because the few studies that have examined it were small. One thing is clear, however: There is a dearth of research on foot changes during pregnancy because pregnant women, in general, are understudied. People are “hesitant to do research on pregnant women, because it’s a sensitive population,” Black said.

During my pregnancy, I was often shocked at how little was known about concerns both minor and monumental: whether eating pineapple would induce contractions, for example, or when the baby would actually be born. Walking, climbing stairs, and having sex are commonly recommended to help induce labor, but “it’s difficult to establish whether they actually worked—or whether labor, coincidentally, started on its own at the same time,” notes What to Expect While You’re Expecting. Pregnancy literature is rife with these sorts of equivocations. Many times over the trimesters, I wondered why so much of pregnancy still felt so medieval, full of guessing, folklore, and hearsay. It’s 2023: Why are new moms still surprised when their feet grow? To this, I have found few satisfactory answers. But at the very least, I have found an ingrown-toenail treatment that works.