Condition

Preeclampsia

Preeclampsia is a serious pregnancy complication, usually appearing after 20 weeks, in which blood pressure climbs and protein shows up in the urine. Calcium and vitamin D have the strongest evidence, and reviews found a lower risk of preeclampsia with both, with moderate-sized effects. The calcium benefit looked clearest in women with low dietary calcium, while the vitamin D finding rested on a single study.

Sources: PMID 39608269; PMID 39716171

Supplements studied: 7
Graded outcomes: 4
Trials: 4
People studied: 44,509

Evidence by supplement

Strong
Moderate
Limited
Very limited

7 supplements

Calcium

Calcium: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Pre-Eclampsia Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	4 studies	15,730 people
Studies that measured pre-eclampsia risk World Health Organization randomized trial of calcium supplementation among low calcium intake pregnant womenAm J Obstet Gynecol · PMID 16522392 Calcium supplementation during pregnancy for preventing hypertensive disorders and related problemsCochrane Database Syst Rev · PMID 24960615 Risk factors associated with preeclampsia in healthy nulliparous women. The Calcium for Preeclampsia Prevention (CPEP) Study GroupAm J Obstet Gynecol · PMID 9396883 and 1 more on the Calcium page

Vitamin D

Vitamin D: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People
	Pre-Eclampsia Risk Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	5,035 people
Studies that measured pre-eclampsia risk Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.BMC Pregnancy Childbirth · PMID 39716171
	Preterm Birth Risk	Changes; see studies			6,055 people

Fish Oil

Infant Birth Weight: improves
Pre-Eclampsia Risk: changes; see studies

Fish Oil: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People
	Infant Birth Weight Small Increase	Improves (the measure goes down)	Small effect		2,302 people
	Pre-Eclampsia Risk	Changes; see studies		1 study	1,831 people
Studies that measured pre-eclampsia risk Marine oil, and other prostaglandin precursor, supplementation for pregnancy uncomplicated by pre-eclampsia or intrauterine growth restrictionCochrane Database Syst Rev · PMID 16856006

Probiotics

All-Cause Mortality
Pre-Eclampsia Risk: changes; see studies

Probiotics: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People
	All-Cause Mortality No effect		NoneNo effect	1 study	7,735 people
Studies that measured all-cause mortality The effects of probiotics administration during pregnancy on preeclampsia and associated maternal, fetal, and newborn outcomes: a systematic review and meta-analysis.Am J Obstet Gynecol MFM · PMID 38447676
	Pre-Eclampsia Risk	Changes; see studies			7,735 people

Selenium

Pre-Eclampsia Risk: changes; see studies

Selenium: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Pre-Eclampsia Risk	Changes; see studies		3 studies	166 people
Studies that measured pre-eclampsia risk Selenium and Preeclampsia: a Systematic Review and Meta-analysisBiol Trace Elem Res · 2016 · PMID 26516080 Selenium supplementation and the incidence of preeclampsia in pregnant Iranian women: a randomized, double-blind, placebo-controlled pilot trialTaiwan J Obstet Gynecol · PMID 20708525 Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trialBr J Nutr · PMID 24708917

Magnesium

Pre-Eclampsia Risk: changes; see studies

Magnesium: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Pre-Eclampsia Risk	Changes; see studies		2 studies	2,653 people
Studies that measured pre-eclampsia risk Oral Magnesium Supplementation for the Prevention of Preeclampsia: a Meta-analysis or Randomized Controlled Trials.Biol Trace Elem Res · PMID 34775542 Magnesium supplementation and preeclampsia in low-income pregnant women - a randomized double-blind clinical trial.BMC Pregnancy Childbirth · PMID 32272914

Coenzyme Q10

Pre-Eclampsia Risk: changes; see studies

Coenzyme Q10: outcomes studied for Preeclampsia
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Pre-Eclampsia Risk	Changes; see studies		1 study	197 people
Studies that measured pre-eclampsia risk Coenzyme Q10 supplementation during pregnancy reduces the risk of pre-eclampsiaInt J Gynaecol Obstet · PMID 19154996

Key findings

Pre-Eclampsia RiskCalciumImproves (the measure goes down)
Infant Birth WeightFish OilImproves (the measure goes down)
All-Cause MortalityProbiotics

The Preeclampsia Prevention protocol

2 primary supplements · 4 supporting supplements

Calcium1,000–2,000 mg daily (starting before 20 weeks)
Low-Dose Aspirin81–150 mg daily at bedtime (starting at 12–16 weeks)

See the full protocol

Studies cited

13 studies from PubMed

Selenium and Preeclampsia: a Systematic Review and Meta-analysisBiol Trace Elem Res, 2016 · PMID 26516080
Efficacy of vitamin D supplementation on the incidence of preeclampsia: a systematic review and meta-analysis.BMC Pregnancy Childbirth · PMID 39716171
Effect of selenium on markers of risk of pre-eclampsia in UK pregnant women: a randomised, controlled pilot trialBr J Nutr · PMID 24708917
Selenium supplementation and the incidence of preeclampsia in pregnant Iranian women: a randomized, double-blind, placebo-controlled pilot trialTaiwan J Obstet Gynecol · PMID 20708525
The effects of probiotics administration during pregnancy on preeclampsia and associated maternal, fetal, and newborn outcomes: a systematic review and meta-analysis.Am J Obstet Gynecol MFM · PMID 38447676
Magnesium supplementation and preeclampsia in low-income pregnant women - a randomized double-blind clinical trial.BMC Pregnancy Childbirth · PMID 32272914
Oral Magnesium Supplementation for the Prevention of Preeclampsia: a Meta-analysis or Randomized Controlled Trials.Biol Trace Elem Res · PMID 34775542
Marine oil, and other prostaglandin precursor, supplementation for pregnancy uncomplicated by pre-eclampsia or intrauterine growth restrictionCochrane Database Syst Rev · PMID 16856006
Coenzyme Q10 supplementation during pregnancy reduces the risk of pre-eclampsiaInt J Gynaecol Obstet · PMID 19154996
Effectiveness of calcium supplementation in the prevention of gestational hypertension: A systematic review and meta-analysis of randomised controlled trials.Pregnancy Hypertens · PMID 39608269
Risk factors associated with preeclampsia in healthy nulliparous women. The Calcium for Preeclampsia Prevention (CPEP) Study GroupAm J Obstet Gynecol · PMID 9396883
Calcium supplementation during pregnancy for preventing hypertensive disorders and related problemsCochrane Database Syst Rev · PMID 24960615
World Health Organization randomized trial of calcium supplementation among low calcium intake pregnant womenAm J Obstet Gynecol · PMID 16522392