Wiivv Blog What can pregnancy teach us about comfort and product design?

Hello My name is Carly, I am the Senior Biomechanical Engineer at Wiivv.  I am also a new mom, a longtime spouse, a science fiction & fantasy (yes, both) enthusiast and a science geek working to expand the role of biomechanics and women in product design. My role at Wiivv is typical for an early employee of a startup (proudly number 5).  Most of my time has been spent as a biomechanical engineer performing the product development and validation research necessary to build great footwear.  Now that you know my personal bias, I can tease you with the story in this blog post: designing footwear products as a woman, FOR women, that to my delight, ended up supporting me (literally) through my first pregnancy and postpartum journey.  Ok, that is a bit dramatic, but my Wiivv Custom Insoles and Sandals were one of the few products (shout out to maternity tights) that kept me comfortable throughout my pregnancy.   Designing for women One of the most laughable/frustrating biases that exists in product design is the fact that most things are designed with an average male as the default. This means that we’re designing things without considering 50% of the population.  The repercussions of this bias are far-reaching. Perhaps the best example I came across was in the automotive industry. Since the 1950s, car safety tests have been done using a standard crash test dummy based on the average male body. In 2011 the industry addressed this issue by introducing a “female” crash test dummy.  However, this female dummy was just a scaled-down version of the male dummy (i.e. NOT anatomically accurate to a woman's body). If that weren’t enough, this “female” dummy is only included in one of five tests for car safety AND is tested only in the passenger seat.  So...if, like me, you are a woman that likes and/or needs to drive, you can expect higher rates of serious injury (75% greater odds than men!!1) when accidents occur.   We can do better If you would like to go deeper on this subject I highly recommend checking out any of the content that Caroline Criado Perez has published.  In particular, her book was very helpful to me when I was looking for resources to explain gender bias in product development.2  In my opinion, the best way of combating this gender bias in the development of products is two-fold.  First, have more women designing and engineering products.  Second, collect disaggregated gender data (data separated by gender).   Footwear for women It turns out footwear and crash test dummies have a few things in common. In the early 19th century, footwear shifted from a customized craft to a mechanized mass-manufactured process.  These innovations were made possible through advancements in the shoe lasting process.  The impetus is thought to be boots for British soldiers. A shoe last is the key ingredient involved in producing almost all of the shoes we see today.  Its form gives shoes their shape and ultimately determines whether a person will have good or bad shoe fit.  Unfortunately, for shoes (and the wearers of shoes), the shift from a highly customized shoe built in the early 19th century to the highly mechanized procedure for mass production eliminated nearly all opportunities for customizing fit (e.g. different from the beginning, made for men and no difference between right and left shapes). We have certainly come a long way since then. Or have we? Most footwear brands are incredibly secretive about their last shapes and sizes but it is understood that the VAST MAJORITY of these lasts are built off of an anatomically correct male foot.  This is supported by the fact that most women’s shoes are less comfortable than men’s shoes, and women's general satisfaction with their footwear is lower than their male counterparts. One of my favorite people in footwear, Dr. Geoffrey Gray summarizes this issue nicely here.3 At Wiivv, we designed our Men’s and Women’s Custom Sandals off of tens of thousands of digital scans of men’s and women’s feet.  We understand that each gender group has different needs, wants and requirements for footwear products.  Below you can see overall comfort and satisfaction (likelihood to recommend them to a friend) for Wiivv sandals disaggregated by gender.     When taking gender into account during the product development process of Wiivv Custom Sandals, we see very similar comfort scores among male and female customers.  Subjects report the two highest comfort levels 79 and 74 percent of the time, respectively.  Additionally, we managed to produce identical mean scores (8.3) for likelihood to recommend across male and female gender categories.  For the product managers among us, this corresponds to an NPS of 51 and 49 for male and female customers, respectively. At Wiivv, we recognize that there is still work to be done to improve the experience of our products for women. If we take a closer look and build a numeric scale for comfort using the data displayed above, we actually find an interesting story. It appears as though the median comfort scores for men and women are identical, however, there is much greater variance within the data for women.   If Wiivv did not collect disaggregated data, these insights would not appear to be obvious. I’m incredibly proud of the fact that we have made an effort to design our products across gender categories with data and insights respective to those groups.  How did we do this for the Wiivv Custom Sandal? 2 of the 5 footwear engineers/designers are women and our Head of Product was a woman.   We disaggregated data by gender.  This included all the market insight data we used to develop design constraints as well as foot biometric data acquired from our digital foot scans. This is why you see two dramatically different designs when you look at our men’s and women’s Custom Sandals. We intend to continue leading the footwear industry in efforts to build products that are customized with the individual in mind, starting with one’s gender.   It gets bigger: Pregnancy and feet An even more precise problem among products made for women are products designed for pregnant women. Roughly 85% of women end up getting pregnant4, and in 2025, the global market size for pregnancy care products is projected to exceed  $33 million USD.5  For many businesses, it would appear negligent to ignore this segment if your products can solve real problems related to pregnancy.  During pregnancy, each woman’s body responds differently. Some common themes to ponder when considering footwear include: Your body releases a LOT of estrogen and relaxin. This helps your ligaments and tissues accommodate uterus growth of 500-1000 times normal size!6 You begin to carry more weight  Your biomechanics adjust as your pelvis shifts position.  You take on more of a waddle to get around (I was particularly enamored with my unique waddle). The combination of relaxin, added weight, and altered biomechanics is a potent recipe for sore feet and fallen arches. Evidence shows that pregnancy can lead to permanently fallen arches.7   Issues associated with fallen arches include plantar fasciitis, leg and back pain,  tired and achy feet.  I was adamant about wearing my Wiivv Custom Insoles and Wiivv Custom Sandals throughout my pregnancy to avoid fallen arches and keep my feet comfortable and pain-free. Two days before my son was born   Footwear is critical to preventing pain and discomfort and remaining mobile while pregnant. For example, walking is one of the best ways to maintain cardiovascular health and keep the core and pelvic floor strong. During my pregnancy I used Wiivv Fit Technology to measure my feet every two weeks, starting in my 21st week.  Below is a table describing the difference between right foot metrics when I was 35 weeks pregnant and those when I was 21 weeks pregnant.   Differences in my feet at 35 and 21 weeks pregnant   My ankle, instep and forefoot circumference, known as volume biometric variables, showed the most significant change. This is likely because they are impacted by swelling on all sides of the foot. The visual below shows a 3D model of my foot at 21 weeks pregnant in blue and 35 weeks pregnant in grey. Swelling is very apparent on the top side of the foot and at the back of the ankle, which is why my foot length went up by 3 mm.   Comparing my feet at 21 weeks (blue) and 35 weeks (grey) pregnant  In my experience, the 4 most important parameters for good shoe fit include forefoot circumference, length, width, and instep height. As you can see in the graphs shown below, all 4 of these biometric variables went up by quite a bit by the time I was 35 weeks pregnant.     These two visuals clearly indicate that shoe fit would become highly problematic during pregnancy - something I can personally attest to. As a result, I pretty much lived in my Wiivv Custom Sandals because they allowed for my feet to swell (adjustable straps) and did a stellar job at supporting my foot and body due to the custom arch support.  The interesting thing about my feet during my pregnancy is that my arches did not really fall from start to end.  If you take a look at my arch shape at various weeks during pregnancy (see the figure below), it was fairly consistent. This could be due to the fact I was extremely diligent about wearing my custom insoles and sandals whenever possible to make sure my body was properly supported.     It would have been ideal to have more information about how my feet were changing at 37 and 39 weeks, but unfortunately, I didn’t get a chance to collect this data. My son surprised me by arriving 3 weeks early 🙃.   Postpartum Going further down the “underserved people” theme, if you think there are not enough products designed with pregnancy in mind, there are even fewer for postpartum. Since this was my first pregnancy I was nervous about postpartum, because of what I had read about the emotional and psychological side of things, where new mothers can find