Physiologic Alterations
Muscle function. Researchers have identified changes in antepartum
and postpartum gastrocnemius muscle metabolism, a
proxy for muscle atrophy, in two longitudinal studies of women
hospitalized on bed rest. Both studies began on hospital admission, ended at6 weeks postpartum, and assessed reoxygenation of the gastrocnemius muscle during recovery from plantar flexion exercise.
The length of time needed for the gastrocnemius muscle to
reoxygenate after plantar flexion exercise significantly
increased (i.e., muscle metabolism deteriorated) across ABR
and decreased (i.e., muscle metabolism improved) during postpartum
recovery. In comparison, gastrocnemius muscle reoxygenation
after exercise among normal controls did not change
over time. Furthermore, women treated with bed rest at home
prior to hospital admission had significantly longer lengths of
muscle reoxygenation time after exercise than women whose
bed rest began on hospital admission. One worrisome finding
was that muscle recovery for women treated with bed rest was
not complete at 6 weeks postpartum. Maternal reports of postpartum
difficulty with mobility, soreness of weight-bearing
muscles, and symptoms of cardiovascular deconditioning supported
the presence of postpartum musculoskeletal and cardiovascular
deconditioning.
Maternal weight. During bed rest in nonpregnant persons,
weight loss often occurs due to loss of fluids, muscle, bone, and
at times, appetite. Carbohydrate and fat metabolism are also
altered by bed rest. Weight gain during pregnancy, however,
is critical to fetal outcome. In three studies of maternal weight gain during ABR,
researchers found that women lost or did not gain weight
. In the first study, in which the sample comprised 18
women with either a singleton or multiple gestation, the
amount of weight gained during hospital bed rest was significantly
lower than in healthy pregnant controls . In a larger study of 141 women with singleton pregnancies
researchers examined changes in body mass index (BMI)
during ABR. Weekly maternal weight
gain was significantly lower than Institute of Medicine (IOM,
1990) recommendations that women with a normal BMI gain