Preeclampsia is defined as the combination of high blood pressure (hypertension), swelling (edema), and protein in the urine (albuminuria, proteinuria) developing after the 20th week of pregnancy.1 Preeclampsia ranges in severity from mild to severe; the mild form is sometimes called proteinuric pregnancy-induced hypertension2 or proteinuric gestational hypertension.3
Women with even mild preeclampsia must be monitored carefully by a healthcare professional. Hospitalization may be necessary to enable close observation.4
The cause of preeclampsia is unknown, although several factors have been shown to contribute.5 6 Preeclampsia is more common in women during their first pregnancy,7 as well as in women who are obese,8 9 who have diabetes,1011 12 13 Women who have had preeclampsia during a previous pregnancy are also at increased risk.1415 antioxidant deficiencies,16 17 18 older maternal age,19 and job stress.20 21 22 or who have gestational hypertension. Preeclampsia has also been associated with calcium deficiencies,
What are the symptoms of preeclampsia?
Symptoms, which typically appear after the 20th week of pregnancy, include swelling of the face and hands, visual disturbances, headache, and high blood pressure. In severe preeclampsia, symptoms are more pronounced. Jaundice may also be present. Severe preeclampsia may lead to seizures (eclampsia) and may cause death to both mother and fetus if left untreated.23 Like eclampsia, severe preeclampsia is a medical emergency requiring hospitalization.24 25
Dietary changes that may be helpful for preeclampsia
Unlike other conditions that cause high blood pressure, salt restriction and use of diuretics can worsen preeclampsia by reducing blood flow to the kidneys and placenta.26 In preeclampsia, unrestricted use of salt and an increased consumption of water are needed to maintain normal blood volume and circulation to the placenta.27
Data from one preliminary study suggest diets high in trans fatty acids are associated with an increased risk of preeclampsia.28 Trans fatty acids are found in foods that contain partially hydrogenated vegetable oils, such as margarine. Foods that have been deep-fried (e.g., French fries) are also rich sources of trans fatty acids.
Lifestyle changes that may be helpful for preeclampsia
Regular prenatal care is essential for the prevention and early detection of preeclampsia.
Job stress (lack of control over work pace and the timing and frequency of breaks) may be detrimental, and reducing job stress may be beneficial in the prevention of preeclampsia.29 In a preliminary study, women exposed to high job stress were found to be at greater risk of developing preeclampsia and, to a lesser extent, gestational hypertension than were women exposed to low job stress. In this study, evaluation of job stress was based on scores assessing on-the-job psychological demand and decision-making latitude. High stress was defined as high psychological demand with low decision latitude, and low stress was defined as low-demand, high-latitude.30
For women with preeclampsia, obstetricians and midwives often recommend bed rest and lying on the left side; this position helps reduce edema and lower blood pressure by increasing urinary output.31 However, a review of clinical trials concluded that bed rest can significantly worsen pregnancy-induced hypertension.32 Women with preeclampsia should discuss the pros and cons of bed rest with their doctors.
Nutritional supplements that may be helpful for preeclampsia
Calcium deficiency has been associated with preeclampsia.33 In numerous controlled trials, oral calcium supplementation has been studied as a possible preventive measure.34 35 36 37 While most trials have found a significant reduction in the incidence of preeclampsia with calcium supplementation,38 39 40 41 42 43 some have reported no change.44
An analysis of double-blind trials45 found calcium supplementation to be highly effective in preventing preeclampsia. However, a large and well-designed double-blind trial46 and a critical analysis47 of six double-blind trials48 49 50 51 52 53 concluded that calcium supplementation did not reduce the risk of preeclampsia in healthy women at low risk for preeclampsia. For healthy, high-risk (i.e., calcium deficient) women, however, the data show a clear and statistically significant beneficial effect of calcium supplementation in reducing the risk of preeclampsia.54 55 56
The National Institutes of Health recommends an intake of 1,200 to 1,500 mg of elemental calcium daily during normal pregnancy.57 In women at risk of preeclampsia, most trials showing reduced incidence have used 2,000 mg of supplemental calcium per day.58 Nonetheless, many doctors continue to suggest amounts no higher than 1,500 mg per day.
Women with preeclampsia have been shown to have elevated blood levels of homocysteine.59 60 61 62 Research indicates elevated homocysteine occurs prior to the onset of preeclampsia.63 Elevated homocysteine damages the lining of blood vessels,64 65 66 67 68 69 70 which can lead to the preeclamptic signs of elevated blood pressure, swelling, and protein in the urine.71
In one preliminary trial, women with a previous pregnancy complicated by preeclampsia and high homocysteine supplemented with 5 mg of folic acid and 250 mg of vitamin B6 per day, successfully lowering homocysteine levels.72 In another trial studying the effect of vitamin B6 on preeclampsia incidence, supplementation with 5 mg of vitamin B6 twice per day significantly reduced the incidence of preeclampsia. Women in that study were not, however, evaluated for homocysteine levels.73 In fact, no studies have yet determined whether lowering elevated homocysteine reduces the incidence or severity of preeclampsia. Nevertheless, despite a lack of proof that elevated homocysteine levels cause preeclampsia, many doctors believe that pregnant women with elevated homocysteine should attempt to reduce those levels to normal.
A marginal zinc deficiency has been reported in some women with preeclampsia.74 75 The common practice of prescribing iron and folic acid supplements to pregnant women can lead to reduced zinc absorption.76 Trials studying the relationship between zinc supplementation and preeclampsia incidence have produced conflicting results. In one double-blind trial, the incidence of preeclampsia was significantly lower in women receiving a multivitamin-mineral supplement, which provided 20 mg of zinc per day, than in women who received the same supplement without zinc.77 However, in another double-blind trial, a higher incidence of preeclampsia was reported in pregnant women given 20 mg of zinc per day than was reported in women given a placebo.78 In yet another trial, zinc supplementation failed to prevent preeclampsia. 79 Therefore, current evidence does not sufficiently support the use of zinc as a way to protect against preeclampsia.
Fish oil supplementation has been proposed to lower the incidence of preeclampsia.80 81 However, controlled clinical trials suggest that fish oil does not reduce symptoms82 or protect against preeclampsia.83 84
Women with preeclampsia have been found to be depleted in antioxidants.85 86 Some87 88 but not all studies89 have reported deficiencies in vitamin C, vitamin E, and beta-carotene in preeclampsia patients. In a double-blind trial, supplementation of vitamin C (one gram per day) and vitamin E (400 IU per day) reduced the incidence of preeclampsia by 76% in women at high risk.90 However, for those already suffering from this condition, supplementation with these same vitamins has led to only insignificant effects.91
Magnesium deficiency has been implicated as a possible cause of preeclampsia.92 93 94 95 96 Magnesium supplementation has been shown to reduce the incidence of preeclampsia in high-risk women in one trial,97 but not in another double-blind trial.98
Women who are deficient in vitamin B2 (riboflavin) are more likely to develop preeclampsia than women with normal vitamin B2 levels.99 These results were observed in a developing country, where vitamin B2 deficiencies are more common than in the United States. Nevertheless, insufficient vitamin B2 may contribute to the abnormalities underlying the disease process.
Are there any side effects or interactions with preeclampsia?
Refer to the individual supplement for information about any side effects or interactions.