An Exploratory Analysis of the Utility of Adding Cardiorespiratory Biofeedback in the Standard Care of Pregnancy-Induced Hypertension

Gestational hypertension and preeclampsia are common disorders during pregnancy, with the majority of cases developing at or near term. The development of mild hypertension or preeclampsia at or near term is associated with minimal maternal and neonatal morbidities. In contrast, the onset of severe gestational hypertension and/or severe preeclampsia before 35 weeks' gestation is associated with significant maternal and perinatal complications. Women with diagnosed gestational hypertension-preeclampsia require close evaluation of maternal and fetal conditions for the duration of pregnancy, and those with severe disease should be managed in-hospital. The decision between delivery and expectant management depends on fetal gestational age, fetal status, and severity of maternal condition at time of evaluation. Expectant management is possible in a select group of women with severe preeclampsia before 32 weeks' gestation. Steroids are effective in reducing neonatal mortality and morbidity when administered to those with severe disease between 24 and 34 weeks' gestation. Magnesium sulfate should be used during labor and for at least 24 hours postpartum to prevent seizures in all women with severe disease. There is an urgent need to conduct randomized trials to determine the efficacy and safety of antihypertensive drugs in women with mild hypertension-preeclampsia. There is also a need to conduct a randomized trial to determine the benefits and risks of magnesium sulfate during labor and postpartum in women with mild preeclampsia.

Oxidative stress has been implicated in the pathophysiology of pre-eclampsia. This randomised controlled trial investigated the effect of supplementation with vitamins C and E in women at increased risk of the disorder on plasma markers of vascular endothelial activation and placental insufficiency and the occurrence of pre-eclampsia. 283 women were identified as being at increased risk of pre-eclampsia by abnormal two-stage uterine-artery doppler analysis or a previous history of the disorder and were randomly assigned vitamin C (1000 mg/day) and vitamin E (400 IU/day) or placebo at 16-22 weeks' gestation. Plasma markers of endothelial activation (plasminogen-activator inhibitor 1 [PAI-1]) and placental dysfunction (PAI-2) were measured every month until delivery. Pre-eclampsia was assessed by the development of proteinuric hypertension. Analyses were done by intention to treat, and in the cohort who completed the study. Supplementation with vitamins C and E was associated with a 21% decrease in the PAI-1/PAI-2 ratio during gestation (95% CI 4-35, p=0.015). In the intention-to-treat cohort, pre-eclampsia occurred in 24 (17%) of 142 women in the placebo group and 11 (8%) of 141 in the vitamin group (adjusted odds ratio 0.39 [0.17-0.90], p=0.02). In the cohort who completed the study (81 placebo group, 79 vitamin group), the odds ratio for pre-eclampsia was 0.24 (0.08-0.70, p=0.002). Supplementation with vitamins C and E may be beneficial in the prevention of pre-eclampsia in women at increased risk of the disease. Multicentre trials are needed to show whether vitamin supplementation affects the occurrence of pre-eclampsia in low-risk women and to confirm our results in larger groups of high-risk women from different populations.