Pregnancy Boosts Size of Women's Feet, Study Finds

These changes may also increase risk for arthritis, researcher says.

MONDAY, March 4 (HealthDay News) -- A new study may help confirm what some women have long suspected -- that pregnancy permanently changes the size and shape of their feet.

Among pregnant women, flat feet are a common problem. The arch of the foot flattens out, possibly because of the extra weight and increased looseness of the joints associated with pregnancy, the University of Iowa researchers explained.

This loss of arch height appears to be permanent, according to the study in the March issue of the American Journal of Physical Medicine & Rehabilitation.

"I had heard women reporting changes in their shoe size with pregnancy, but found nothing about that in medical journals or textbooks," Neil Segal, an associate professor of orthopedics and rehabilitation, said in a university news release.

"In order to study this more scientifically, we measured women's feet at the beginning of their pregnancy and five months after delivery," Segal said. "We found that pregnancy does indeed lead to permanent changes in the feet."

Segal and colleagues followed 49 pregnant women, collected arch measurement during the first trimester of pregnancy and again about five months after childbirth. In 60 to 70 percent of the women, their feet became longer and wider -- as much as one-third inch longer in some cases.

First pregnancies may cause the greatest amount of foot change, while subsequent pregnancies may not further alter foot structure, according to the researchers.

"We know that women, and especially women who have had children, are disproportionately affected by musculoskeletal disorders," said Segal, who also is an associate professor of radiology and epidemiology and director of the university's 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," Segal added.

Segal plans further studies to examine whether pregnancy-related foot changes may lead to arthritis or other problems later in life. He's also conducting research into ways to protect women's musculoskeletal health during pregnancy.

More information

The U.S. Office on Women's Health has more about pregnancy-related body changes and discomforts.