Endocrine changes occurring during pregnancy result in increased laxity of the ligaments of the foot. This may lead to gradual collapse of the foot arches. The aim of the study was to determine whether pregnancy and body mass index (BMI) had a role in affecting the foot arches at long term. A collapsed arch results in widening of the feet, thus altering the foot size. The control group included nulliparous women, while the study group included women who had been pregnant at least once. The groups were stratified secondarily by obesity according to BMI. We reviewed over 1000 charts at the outpatient offices in a large Mid-Western city. The age, BMI, and shoe size in an athletic shoe were recorded. There were 40 subjects in the control group and 70 in the study group. 19/40 women in control and 46/70 in study group experienced a change in shoe size (P = 0.06). Of those affected, the non-obese control group experienced a 9.7% change in shoe size while the obese study group experienced a 15.5% change (P < 0.05). There was neither a change in size between women who had been pregnant and the nulliparous, nor was there a difference between the obese and non-obese. However, there was a statically significant difference between those affected who were both non-obese and nulliparous and those who had been pregnant and who are obese. Individually, the effect of pregnancy and BMI are highly suggestive and clinically relevant.