A University of Iowa study confirms what many women have
long suspected—that pregnancy permanently changes the size and shape of their
Flat feet are a common problem for pregnant women. The arch
of the foot flattens out, possibly due to the extra weight and increased
looseness (laxity) of the joints associated with pregnancy. The new study,
published in the March issue of the American
Journal of Physical Medicine & Rehabilitation, suggests that this loss
of arch height is permanent.
"I had heard women reporting changes in their shoe size
with pregnancy, but found nothing about that in medical journals or
textbooks," says Neil Segal, UI associate professor of orthopaedics and
rehabilitation. "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
How the study was
The UI 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% 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 2 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.
"We know that women, and especially women who have had
children, are disproportionately affected by musculoskeletal disorders,"
says Segal, who also is an associate professor of radiology and epidemiology at
the UI, 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."
Segal plans further studies to assess whether these foot
changes lead to health problems, like arthritis, later in life. He also is
conducting studies of how women's musculoskeletal health can be protected
In addition to Segal, the research team included Elizabeth
Boyer; Patricia Teran-Yengle; Natalie Glass; Howard Hillstrom; and John Yack.
The study was funded in part by grants from the American Geriatrics Society and
the National Institute on Aging.