Various strategies used to prevent or modiy preeclampsia severity have been evaluated. Some are listed in Table 40-6. In general, none of these has been found to be convincingly and reproducibly efective.
Dietary "treatment" for preeclampsia has produced some interesting abuses (Chesley, 1978). A low-salt diet was one of the earliest research eforts to prevent preeclampsia (De Snoo, 1937). This was followed by years of inappropriate diuretic therapy. Although these practices were discarded, it ironically
TABLE 40-6. Some Methods to Prevent Preeclampsia That Have Been Evaluated in Randomized Trials
Dietary manipulation-low-salt diet, calcium or fish oil
Exercise-physical activity, stretching
Cardiovascular drugs-diuretics, antihypertensive drugs
Antioxidants-ascorbic acid (vitamin C), a-tocopherol (vitamin E), vitamin D
Antithrombotic drugs-low-dose aspirin, aspirin/ dipyridamole, aspirin + heparin, aspirin + ketanserin
Modified from Staff, 2015.
was not until relatively recently that the irst randomized trial was done and showed that a sodium-restricted diet was inefective in preventing preeclampsia (Knuist, 1998).
Regular exercise during pregnancy is linked to a lower risk of developing preeclampsia (Barakat, 2016; Morris, 2017). Also, in one systematic review, a trend toward risk reduction with exercise was noted (Kasawara, 2012). Only a few studies have been randomized, and thus, more research is needed (Staf, 2015).
Somewhat related, Abenhaim and coworkers (2008) reported a retrospective cohort study of 677 nonhypertensive women hospitalized for bed rest because of threatened preterm delivery. When outcomes of these women were compared with those of the general obstetrical population, bed rest was associated with a signiicantly reduced relative risk-0.27-of developing preeclampsia. From two small randomized trials, prophylactic bed rest for 4 to 6 hours daily at home was successful in signiicantly lowering the incidence of preeclampsia in women with normal blood pressures (\1eher, 2006).
Calcium supplementation has been studied in several trials, including one by the National Institute of Child Health and Human Development (NICHD) that included more than 4500 low-risk nulliparas (Levine, 1997). Calcium supplementation did not prevent preeclampsia or pregnancy-associated hypertension. In one metaanalysis, increased calcium intake in high-risk women lowered the risk for preeclampsia (Patrelli, 2012). However, in aggregate, most of these trials have shown that unless women are calcium deficient, supplementation has no salutary efects (Sanchez-Ramos, 2017; Staf, 2015).
Cardioprotective aty acids found in some fatty fishes are plentiful in diets of Scandinavians and American Eskimos. Because supplementation with these fatty acids likely prevents inflammatory-mediated atherogenesis, it was posited that they might also prevent preeclampsia. Unfortunately, randomized trials conducted thus far have shown no such beneits from ish oil supplementation (Makrides, 2006; Olafsdottir, 2006; Zhou, 2012).