Pregnancy brings with it many changes to the body, some you may expect, others come as more of a surprise. A swollen abdomen and larger breasts are two of the most obvious signs of advancing pregnancy. However, a change in the size and shape of your feet might be something you were not expecting. If you do find yourself having to go up a shoe size or two, you can be assured you are not alone. One study found that over 60% of pregnant women had an increase in foot length of between 2 and 10mm, and over 70% experienced an arch drop of between 1 and 5mm.
So, what is the scientific explanation for this phenomenon?
There are two main mechanisms thought to contribute to pregnancy-induced alterations in feet:
- Many women report a swelling of the feet and ankles during pregnancy, particularly in the latter stages. This is due to the body’s increased demand for blood and fluid.
- During pregnancy the placenta releases a hormone called relaxin, which functions to soften the cervix in preparation for delivery. Being fairly non-specific in nature, it also causes increased laxity in other joints and ligaments around the body, including the feet. This, in combination with the extra weight being carried around, can cause a flattening of the foot arch and a change in the malleability of the foot.
For most women, this change is nothing more than a slight inconvenience (or an excuse to go shoe shopping); however, in severe cases ligaments may become strained and gait may be affected, leading to pain in the feet, knees or hips.
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- Segal, N A, et al. “Pregnancy Leads to Lasting Changes in Foot Structure.” American Journal of Physical Medicine & Rehabilitation, vol. 92, no. 3, 1 Mar. 2013, pp. 232–240., doi:10.1097/PHM.0b013e31827443a9
- “Foot Size.” Web MD, www.webmd.com/baby/foot-size.