Changes to foot size and shape are a widespread reality for many women during and after pregnancy. This physical adjustment results from a complex interplay between hormonal shifts, increased body mass, and altered biomechanics during the gestational period. For many women, this change means needing a new, larger shoe size, which can be a surprising and sometimes permanent outcome of carrying a pregnancy.
The Physiological Mechanisms of Foot Change
The primary biological driver for changes in foot structure is the hormone relaxin, which the body produces in large amounts during pregnancy. This hormone increases the flexibility of ligaments to prepare the pelvis for childbirth, but its effects extend to the ligaments and joints in the feet, causing them to loosen.
This hormonal laxity coincides with a significant increase in body weight, which exerts greater pressure on the foot’s arches. The combination of loosened ligaments and increased load causes the arches to flatten, a process known as pronation. This loss of arch height and rigidity forces the foot to lengthen and widen under the extra weight. The shift in the body’s center of gravity forward also contributes to the increased strain on the feet.
Temporary Swelling Versus Structural Change
The perception of “bigger feet” during and immediately after pregnancy is often a combination of two distinct phenomena: temporary swelling and a lasting structural change. Temporary swelling, or edema, is a common experience, particularly in the third trimester and the immediate postpartum period. This is caused by increased blood volume and fluid retention, which gravity pulls down into the feet and ankles.
The structural change, however, is a physical alteration to the foot’s skeletal framework. When the ligaments supporting the arch become stretched and subsequently lengthened due to relaxin and weight-bearing pressure, the foot’s arch drops. This permanent flattening of the arch results in an actual increase in the overall length and/or width of the foot.
Reversibility and Long-Term Impact
The duration of these changes varies depending on the underlying cause. Edema typically resolves within a week or two after delivery as the body excretes the excess fluid and hormone levels begin to normalize. The swelling-related size increase is almost always temporary.
The structural changes, however, are often permanent for a significant percentage of women. Studies have shown that for approximately 60 to 70 percent of women, the feet become permanently longer and wider following pregnancy. This permanent change is due to the sustained loss of arch height, with measurements showing foot length increases between 2 and 10 millimeters, which is enough to require a half or full shoe size increase.
Strategies for Foot Health and Support
Given the potential for lasting changes, proactive measures for foot health and support are beneficial during and after pregnancy. One of the most important steps is selecting proper footwear that accommodates the changing foot shape. Shoes should have a wide toe box to prevent pinching and offer robust arch support to help mitigate the effects of pronation.
To manage temporary swelling, simple actions can provide significant relief. Elevating the feet above heart level whenever possible helps gravity work in reverse to reduce fluid pooling. Light exercise, such as walking, and wearing compression socks can also improve circulation and prevent fluid from accumulating.
For women experiencing significant arch flattening, custom or over-the-counter orthotic inserts can provide additional support and help distribute weight more evenly. If persistent pain, severe changes, or swelling that does not resolve after two weeks occurs, consulting a podiatrist is advisable.