Singapore: According to a study by the University of Iowa, US, the arch of the foot in pregnant women flatten out, possibly due to the extra weight and increased looseness (laxity) of the joints associated with pregnancy.

The study followed 49 pregnant women and collected static and dynamic arch measurements during the first trimester of pregnancy and again about five months after childbirth. The researchers found that for about 60-to-70 percent of the women in the study, their feet became longer and wider.

Specifically, the study showed that, on average, arch height and measures of arch rigidity decreased significantly from early pregnancy-to-five months after childbirth, causing corresponding increases in foot length (between two and 10 mm) and arch drop. However, no significant change in the distribution of foot pressure was detected. The study also suggested that first pregnancies may account for most of the observed changes, while second, third, or higher pregnancies may not further alter foot structure.

"I had heard women reporting changes in their shoe size with pregnancy, but found nothing about that in medical journals or textbooks," says Dr Neil Segal, associate professor of orthopaedics and rehabilitation, University of Iowa. "In order to study this more scientifically, we measured women's feet at the beginning of their pregnancy and five months after delivery. We found that pregnancy does indeed lead to permanent changes in the feet," he added.

"We know that women, and especially women who have had children, are disproportionately affected by musculoskeletal disorders," said. Dr Segal, who also is an associate professor of radiology and epidemiology at the university as well as director of the Clinical Osteoarthritis Research Program. "It is possible that these foot changes that occur during pregnancy may help explain why, in comparison with men, women are at higher risk for pain or arthritis in their feet, knees, hips, and spines."