Not enough evidence to determine if exercise is helpful in preventing pre-eclampsia and its complications.
Pre-eclampsia is a serious complication of pregnancy occurring in about 2% to 8% of women. It is identified by increased blood pressure and protein in the urine, but women often suffer no symptoms initially. It can, through constriction of the blood vessels in the placenta, interfere with food and oxygen passing to the baby, thus inhibiting the baby's growth and causing the baby to be born too soon. Women can be affected through problems in their kidneys, liver, brain, and clotting system. Regular exercise in people who are not pregnant is known to have general health benefits, including increased blood flow and reduced risk of high blood pressure. So there is the potential for exercise to help prevent pregnant women developing pre-eclampsia. There are, however, concerns that there may be adverse effects of exercise taken during pregnancy particularly the possibility of women giving birth too early. The review of trials found two small, well conducted studies but there was insufficient data to say what the potential benefits and harms might be. Further studies are needed, and in the meantime women will be guided by their own beliefs and reasoning, as well as those of their caregivers.
There is insufficient evidence for reliable conclusions about the effects of exercise on prevention of pre-eclampsia and its complications.
[Note: The four citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]
The association between an increase in regular physical activity and a reduction in the risk of hypertension is well documented for non-pregnant people. It has been suggested that exercise may help prevent pre-eclampsia and its complications. Possible adverse effects of increased physical activity during pregnancy, particularly on the risk of preterm birth and fetal growth restriction, are unclear. It is, therefore, important to assess whether exercise reduces the risk of pre-eclampsia and its complications and, if so, whether these benefits outweigh the risks.
To assess the effects of exercise, or increased physical activity, on prevention of pre-eclampsia and its complications.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 1), and EMBASE (2002 to February 2005). We updated the search of the Pregnancy and Childbirth Group's Trials Register on 18 January 2010and added the results to the awaiting classification section.
Studies were included if these were randomised trials evaluating the effects of exercise or increased physical activity during pregnancy for women at risk of pre-eclampsia.
Two review authors independently selected trials for inclusion and extracted data. Data were entered on Review Manager software for analysis, and double checked for accuracy.
Two small, good quality trials (45 women) were included. Both compared moderate intensity regular aerobic exercise with maintenance of normal physical activity during pregnancy. The confidence intervals were wide and crossed the line of no effect for all reported outcomes including pre-eclampsia (relative risk 0.31, 95% confidence interval 0.01 to 7.09).