Bed Rest in Pregnancy Raises Diabetes Risk

CHICAGO -- Women who are prescribed long-term bed rest for troubled pregnancies are at increased risk of developing gestational diabetes, researchers said here.

For every day of bed rest after the first 7 hospitalized days, the risk of gestational diabetes rises 1.04 times, said Audrey Merriam, MD, a resident in obstetrics and gynecology at Christiana Health Care, Newark, Del., at her poster presentation during the annual meeting of the American College of Obstetricians and Gynecologists.

The researchers determined that bed rest greater than 7 days carried a six-fold relative risk of gestational diabetes (P=0.00). They also determined that older maternal age also carried a risk of gestational diabetes (P=0.008) -- a known risk factor for gestational diabetes.

"Our study adds to the mounting evidence that extended bed rest for women having a high-risk pregnancy may do more harm than good," Merriam told MedPage Today.

In her retrospective study that included 509 women admitted for various high-risk pregnancy causes, she sought to determine the impact of bed rest on gestational diabetes. Of that group, 54 women -- 10.6% -- developed gestational diabetes, Merriam reported. She accessed Christiana Health Care patient records in the period from 2007-2012.

The women included for the study were having a singleton pregnancy with no apparent fetal abnormalities. They were at least 18 years old and had no previous history of gestational diabetes or pre-gestational diabetes, and had undergone a 1-hour glucose tolerance test performed during admission. The researchers compared outcomes regarding development of gestational diabetes with women in the study who did not develop the condition to determine characteristics associated with gestational diabetes.

Of all the women in the study, 147 were hospitalized for preeclampsia/hypertension; 138 were hospitalized for preterm premature rupture of membranes; 81 were admitted because of cervical shortening; 60 were admitted because of premature labor; 30 were found to have advanced cervical dilation; and the rest were admitted for other pregnancy-related complications.

Some of the women were hospitalized and then were sent home before delivery; others stayed in hospital until they delivered. "We keep women who break their water early in the hospital until they deliver," Merriam explained. "Women who go into labor early and do not break their water will sometimes get a prolonged hospital stay." For example, she said, "if a women broke her water at 24 weeks, we deliver them at 34 weeks, so we are talking about 70 days in the hospital."

The outcomes for the infants did not appear to be statistically different, Merriam reported. She noted that 37 of the 54 babies born to women who developed gestational diabetes were treated in the neonatal intensive care unit, compared with 339 babies of the 455 women who did not have gestational diabetes (P=0.34). The average length of stay for the infants was 29.7 days for those infants born to mothers with gestational diabetes compared with 30.5 days for those born to women without gestational diabetes (P=0.96).

Parity, prior preterm delivery, smoking status, and hypertension status among the mothers also were not statistically different, the researchers reported.

"Bed rest is a very interesting topic in obstetrics and gynecology," Merriam said. "There is no true definition of it. It means something different to pretty much every provider that you would talk to from what I can tell. In general, people have been trying to get away from placing people on bed rest for a variety of reasons. We have observed that pregnant women who went to work or exercised did fine."

"When you limit the activity of women in the hospital you increase the risk of gestational diabetes, which has its own set of complications," she said. "Limiting activity also increases the risks of blood clots in the legs." She also noted that bed rest may be associated with bone demineralization, pulmonary atelectasis, and muscle deconditioning.

"Restricted activity is one of the most common interventions used in pregnancy," said Anthony Sciscione, MD, director of maternal-fetal medicine at Christiana Health Care. He did not participate in Merriam's study but was aware of her findings.

He said restricted activity is prescribed in cases of antenatal vaginal bleeding to prevent miscarriage; it is used in people with high blood pressure -- particularly in women with preeclampsia -- in the belief that it reduces the risk of bad outcomes.

"What Merriam found is what you would expect: If you are not active you are more likely to have diabetes," Sciscione told MedPage Today. "For all the other indications the bottom line is: There has never been a study that has shown a benefit in terms of outcome either to the mother or the fetus due to activity restriction or bed rest or even something as simple as removal from work or removal from exercise."

In fact, he said that in one recent study on this issue, "women who participated in more activities had a lower risk of preterm birth." He said another study in which women were placed on activity restriction due to shortened cervix were more likely to deliver early -- not later.