Primary prevention
Low-dose aspirin (starting between 12 and 28 weeks' gestation, and optimally before 16 weeks' gestation, and continuing until term) reduces the incidence and severity of preeclampsia.[1][15][16][41][42][43]
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The effect seems to be uniform across all risk groups, but its use should be targeted at high-risk groups such as those with hypertension, diabetes, renal disease, autoimmune disease, multiple pregnancy, a body mass index of >30, a maternal age of >40 years, or an interval of ≥10 years since previous pregnancy.[8][10][15][16] Meta-analyses of randomized controlled trials suggest that the benefits of aspirin may be limited to prevention of early onset rather than term disease, and only when given at doses of >100 mg/day.[44][45]
It is important to optimize treatment for hypertension and renal disease before pregnancy. Controlled weight loss reduces the incidence of preeclampsia.[16] Exercise in pregnancy should be encouraged in the absence of complications, including maternal comorbidities, and risk factors for bleeding or premature delivery. A regular supervised exercise program may reduce the risk of preeclampsia, independently of body mass index.[46][47]
Epidemiologic studies have found that low dietary calcium is associated with preeclampsia. One Cochrane review found that the addition of high-dose calcium (≥1 g/day) reduced the risk of preeclampsia and preterm birth compared with placebo, although the effect was mostly shown in smaller trials, with possible confounding by low dietary calcium intake.[48] In populations in which dietary calcium intake is low, the World Health Organization recommends that pregnant women should receive 1.5 g to 2 g/day of supplementary calcium in order to reduce the severity of preeclampsia.[49] However, large, high-quality studies of calcium supplementation from early pregnancy at a range of doses and in different populations are required.[48][49][50][51]
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Vitamin D supplementation in pregnancy, with or without additional calcium, may reduce the risk of preeclampsia. However, high-quality clinical trials are required to evaluate a range of doses and potential adverse events.[52]
Women with hypertension, including those with an isolated elevated diastolic blood pressure at booking, should be followed up in an increased-frequency surveillance program.
The table that follows summarizes recommendations on prevention of preeclampsia from the American College of Obstetricians and Gynecologists (ACOG).[1]
Note that an individual patient may fall into more than one group, and so interventions might be additive; please review all population and subpopulation groups to assess all that apply.
Pregnant woman; at high risk for preeclampsia; between 12 and 28 weeks’ gestation
Women at high risk are those with ≥ one high-risk factors: previous pregnancy with preeclampsia, especially when accompanied by an adverse outcome; multifetal gestation; chronic hypertension; type 1 or type 2 diabetes; renal disease; and autoimmune disease (e.g., systemic lupus erythematosus, antiphospholipid syndrome).
All
Intervention
Start low-dose aspirin
Low-dose aspirin is recommended as prophylaxis against preeclampsia for all women with high risk features; initiation of low-dose aspirin is recommended between 12 and 28 weeks of gestation, and optimally before 16 weeks of gestation.
Goal
Prevention of preeclampsia
Continue aspirin until delivery.
Pregnant woman; at moderate risk for preeclampsia; between 12 and 28 weeks’ gestation
Women at moderate risk are those with ≥ two moderate-risk factors: nulliparity; obesity (BMI＞30 kg/m²); family history of preeclampsia (mother or sister); sociodemographic characteristics (African American race, low socioeconomic status); age 35 years or older; and personal history factors (e.g., previous pregnancy with a child who was born with low birth weight or small for gestational age, previous adverse pregnancy outcome, and more than 10-year pregnancy interval).
All
Intervention
Consider low-dose aspirin
Consideration of low-dose aspirin as prophylaxis against preeclampsia is recommended for those with more than one moderate-risk factor.
A combination of multiple moderate-risk factors may be used to identify women at increased risk of preeclampsia. These risk factors are independently associated with moderate risk of preeclampsia, some more consistently than others. Moderate-risk factors vary in their association with increased risk of preeclampsia.
If given, initiation of low-dose aspirin is recommended between 12 weeks and 28 weeks of gestation, and optimally before 16 weeks of gestation.
Goal
Prevention of preeclampsia
Continue aspirin until delivery.
Secondary prevention
Low-dose aspirin (starting at 12-14 weeks' gestation) is recommended in subsequent pregnancies. If the risk of preeclampsia is thought to be high (e.g., previous early-onset disease, severe disease), the benefits are clear. However, they are less clear in mild to moderate or late disease, where the outcome is typically good anyway.[1][7][16]
There is some evidence that low molecular weight heparin, with or without aspirin, might reduce the placental insufficiency in preeclampsia, but long-term safety studies are not available.[118][119]
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