You can’t eliminate the risk of preeclampsia entirely, but several evidence-based strategies can significantly lower your chances. The most effective prevention tool is low-dose aspirin, started early in pregnancy for women with known risk factors. Beyond that, regular physical activity, maintaining a healthy weight before conception, and adequate calcium intake all play meaningful roles in reducing risk.
Who Is at Higher Risk
Prevention starts with understanding whether you carry risk factors that make preeclampsia more likely. The U.S. Preventive Services Task Force divides these into two tiers.
A single high-risk factor is enough to warrant preventive treatment. These include a history of preeclampsia in a previous pregnancy, carrying multiples (twins or more), chronic high blood pressure, type 1 or type 2 diabetes diagnosed before pregnancy, kidney disease, or autoimmune conditions like lupus or antiphospholipid syndrome.
Moderate-risk factors carry less individual weight, but having two or more together raises your risk enough to consider preventive measures. These include being pregnant for the first time, a pre-pregnancy BMI over 30, a family history of preeclampsia (your mother or sister), age 35 or older, a gap of more than 10 years between pregnancies, conception through IVF, and lower income. Black women also face elevated risk due to systemic inequities in healthcare access and environmental exposures.
Low-Dose Aspirin: The Strongest Preventive Tool
For women with risk factors, daily low-dose aspirin is the single most effective prevention strategy available. In the United States, guidelines recommend 81 mg daily, started after 12 weeks but before 16 weeks of gestation, and continued until delivery. More recent research suggests that a higher dose of 150 to 162 mg, started between 11 and 14 weeks, may be even more effective at preventing early-onset preeclampsia, though guidelines vary by country.
The recommendation is straightforward: if you have one or more high-risk factors, you should be taking low-dose aspirin. If you have two or more moderate-risk factors, aspirin is also worth discussing with your provider. Timing matters here. Starting aspirin after 20 weeks provides far less benefit, so this is a conversation to have at your first prenatal visit or even a preconception appointment.
Exercise Lowers Risk by Up to 35%
Regular physical activity during the first 20 weeks of pregnancy is associated with a 34% to 35% reduced risk of preeclampsia compared to being inactive. The more vigorous the activity, the greater the benefit. Women who engaged in vigorous exercise saw their risk drop by 54%, while light to moderate activity was linked to a 24% reduction.
You don’t need intense workouts to see a benefit. Brisk walking, defined as a pace of at least 3 miles per hour, was associated with a 30% to 33% lower risk of preeclampsia compared to no walking at all. Even something as simple as regularly climbing stairs showed an inverse relationship with preeclampsia risk. The key is consistency during early pregnancy, not intensity.
Managing Weight Before and During Pregnancy
Pre-pregnancy weight is one of the strongest modifiable risk factors for preeclampsia. Women who are obese before conceiving face two to three times the risk compared to women at a normal weight. In one large study, preeclampsia developed in 6% of overweight and obese women versus 1.7% of normal-weight women.
If you’re planning a pregnancy and carry extra weight, even modest weight loss beforehand can shift your risk profile. Once you’re already pregnant, the focus shifts from weight loss to healthy weight gain within recommended ranges for your BMI category. Crash dieting during pregnancy isn’t safe, but staying physically active and eating well helps manage both weight gain and blood pressure.
Calcium for Women With Low Dietary Intake
The World Health Organization recommends 1.5 to 2 grams of supplemental calcium daily for pregnant women whose diets are low in calcium. This is particularly relevant if you don’t regularly consume dairy products or other calcium-rich foods. In populations where dietary calcium is already adequate, supplementation shows less benefit, so this recommendation is targeted rather than universal.
For context, a glass of milk contains roughly 300 mg of calcium, so reaching 1,500 mg through diet alone requires deliberate effort. If your intake falls short, supplementation is a simple, low-risk way to reduce preeclampsia risk.
Controlling Blood Pressure Before Pregnancy
Women with chronic high blood pressure face a compounded risk of developing superimposed preeclampsia during pregnancy. A landmark trial (the CHAP trial) found that actively treating mild chronic hypertension during pregnancy, starting medication when blood pressure reaches 140/90, reduced a composite of serious outcomes including severe preeclampsia, preterm birth, placental abruption, and fetal or neonatal death by 18%.
This was a significant shift in practice. Previously, mild hypertension in pregnancy was often monitored without treatment. Current guidelines now recommend starting or adjusting blood pressure medication when readings hit 140/90 during pregnancy. If you have chronic hypertension, getting it well-controlled before conception and maintaining that control throughout pregnancy is one of the most important things you can do. Low-dose aspirin is also recommended for all women with chronic hypertension, ideally started before 16 weeks.
Newer Blood Tests for Early Detection
A blood test measuring the ratio of two proteins produced by the placenta can now predict preeclampsia before symptoms appear. When measured between 20 and 24 weeks of gestation, this test identified early-onset preeclampsia (the most dangerous form, occurring before 34 weeks) with 100% sensitivity and 99% specificity. At 30 to 34 weeks, it accurately identified preterm preeclampsia with 86% sensitivity.
This test isn’t yet standard in routine prenatal care everywhere, but it’s increasingly available and can be especially useful for women whose risk status is uncertain. Early identification doesn’t prevent preeclampsia directly, but it allows for closer monitoring, timely aspirin initiation, and planned delivery when needed.
Warning Signs to Act On Quickly
Even with every prevention strategy in place, preeclampsia can still develop, typically after 20 weeks. Knowing the warning signs lets you get help before the condition becomes severe.
- Severe headaches that don’t respond to usual remedies
- Vision changes including blurred vision, light sensitivity, or temporary vision loss
- Upper belly pain, usually under the ribs on the right side
- Shortness of breath from fluid buildup in the lungs
- Nausea or vomiting that appears suddenly in the second half of pregnancy
Any of these symptoms warrants immediate medical attention. Preeclampsia can escalate within hours, and early intervention protects both you and your baby. Regular prenatal visits, where blood pressure is checked at every appointment, remain one of the simplest and most effective forms of surveillance.