Condition guide · 9 min read

Pre-eclampsia prevention — supplements with credible evidence

Updated 2026-05-20 · Reviewed by SupplementScore editors · No sponsorships

Pre-eclampsia is a hypertensive disorder of pregnancy and a leading cause of maternal and neonatal morbidity worldwide. The single most effective preventive intervention in high-risk pregnancies is low-dose aspirin started before 16 weeks — a medication, not a supplement. Among supplements, calcium has the strongest WHO/USPSTF-supported evidence in low-calcium-intake populations. The role of vitamin D, omega-3, and L-arginine is more nuanced, with positive trial signals that depend on baseline status and risk profile.

This belongs with your obstetric provider. Pre-eclampsia risk stratification (first pregnancy, prior pre-eclampsia, chronic hypertension, diabetes, autoimmune disease, BMI, age, multiple gestation, IVF, family history) determines whether low-dose aspirin and calcium are indicated. Headaches, visual changes, RUQ pain, swelling, or BP changes during pregnancy need urgent obstetric review.

What ACOG, USPSTF, and WHO actually recommend

The 2021 USPSTF, ACOG, and SMFM guidelines recommend low-dose aspirin (81 mg/day, started between 12 and 16 weeks gestation) for women at high risk of pre-eclampsia. The WHO additionally recommends calcium supplementation in populations with low dietary calcium intake (<900 mg/day) — most low- and middle-income countries — to reduce pre-eclampsia and preterm birth risk. These are the two most clearly evidence-supported preventive strategies. Everything below is adjunctive.

Supplements with credible adjunctive evidence

Tier 1 · WHO recommendation in low-calcium-intake populations

Calcium

1.5–2 g/day in divided doses, from week 20 until delivery

The 2018 Cochrane review of 27 trials found calcium supplementation reduced the risk of pre-eclampsia by approximately 55% in low-calcium-intake populations, with smaller benefit in calcium-replete populations. ACOG considers calcium supplementation in populations with dietary intake <600 mg/day. Take separately from iron supplements (compete for absorption) and separately from any prescribed levothyroxine.

Tier 2 · Deficiency repletion; broader pregnancy benefit

Vitamin D3

600–2000 IU/day, titrated to 25-OH-D 30–50 ng/mL

Vitamin D deficiency is associated with increased pre-eclampsia risk in observational and some interventional work. The 2019 Cochrane review found a modest reduction in pre-eclampsia risk with supplementation, though heterogeneity is high. Vitamin D deficiency itself is common in pregnancy and has broader maternal and fetal implications (bone, immune, fetal growth). Test 25-OH-D and supplement to the normal range — the ACOG-recommended pregnancy intake is 600 IU/day; higher doses may be appropriate in documented deficiency.

Tier 2 · Fetal neurodevelopment; possible pre-eclampsia signal

Omega-3 (EPA/DHA)

200–500 mg DHA/day, with additional EPA acceptable

The pre-eclampsia-specific signal for omega-3 is modest; the bigger reason to prioritise DHA in pregnancy is fetal neurodevelopment (the FDA and ACOG recommend ≥200 mg DHA/day in pregnancy). Some meta-analyses suggest a modest reduction in pre-term delivery with higher omega-3 intake. Use a third-party-tested product low in heavy metals. Plant-derived (algal) DHA is acceptable for vegetarian pregnancies.

Tier 2 · Endothelial NO support; trial signal in high-risk groups

L-Arginine

3 g/day in divided doses, in selected high-risk patients with obstetric supervision

L-arginine supplementation has shown reduced pre-eclampsia incidence in high-risk populations in several trials (Vadillo-Ortega 2011 RCT in Mexico; Camarena Pulido 2015 RCT). Mechanism is improved endothelial nitric-oxide signalling. Not currently a standard recommendation in most jurisdictions; consider only with explicit obstetric guidance.

What to skip

Practical priority list. Risk stratification at booking → low-dose aspirin 81 mg/day from 12–16 weeks if high-risk → calcium 1.5–2 g/day if dietary calcium is low or in low-calcium-intake populations → adequate prenatal (folate, iron, DHA) → vitamin D repletion to normal range → individualised consideration of L-arginine only with obstetric input → close BP and urine-protein monitoring. Anything outside this list should be specifically discussed with your provider.

Sources

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