Pregnancy-induced high-blood-pressure

Overview

Research on supplements for pregnancy-induced high-blood-pressure is limited and mostly inconclusive. Vitamin B9 (Folate) (3 studies) alone does not appear to lower gestational high-blood-pressure risk, though folic acid within a multivitamin may relate to preeclampsia outcomes. Vitamin D (3 studies) also does not appear to reduce this risk based on low-quality trials.

Single small studies of Selenium, Sulforaphane, and Black Tea provide only preliminary or conflicting signals. Black tea drinking during pregnancy was associated with higher high-blood-pressure risk in one study, though causality is uncertain. See the heatmap and evidence reviews below for individual supplement summaries.

Effect graph

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Relevant supplements

Relevant supplements sorted by DEX Score.


Vitamin D	★★★★★	Low
Vitamin B9 (Folate)	★★★★★	Very Low / None
Sulforaphane	★★★★★	Low
Selenium	★★★★★	Very Low / None
Black Tea	★★★★★	Very Low / None

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Studies

Find individual evidence reviews for supplements sorted by DEX Score.

5 supplements for and rated at least stars. All purchase bands. No minimum star filter.

Vitamin DView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceMediumTrustMedium

Evidence Review

It is not clear if taking vitamin D during pregnancy helps prevent high blood pressure caused by pregnancy.
Studies so far, which are of low quality, show that vitamin D does not reduce the risk of this condition.

Browse 3 studies

GuideVitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline2024

The 2024 Endocrine Society guideline suggests empiric vitamin D for children, adults ≥75, pregnancy, and high-risk prediabetes, but not routine use in healthy younger adults.

Population: Pregnant women
Ages: 1–18

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MetaVitamin D supplementation for women during pregnancy2024n=1,368

An updated Cochrane review of 10 RCTs (2,313 pregnant women) found vitamin D alone may reduce severe postpartum hemorrhage and low birthweight, but evidence was low to very low certainty.

Effect: Benefit
Population: Women
Participants: 1,368

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MetaVitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials2017n=8,406

A systematic review of 43 prenatal vitamin D RCTs (8,406 participants) found supplementation increased birth weight and reduced wheeze by age 3 but showed limited maternal clinical benefit.

Effect: Benefit
Dose: 600 IU/day
Population: Pregnant women
Participants: 8,406

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SulforaphaneView supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustLow

Evidence Review

It is not known if sulforaphane from broccoli helps lower high blood pressure during pregnancy.
In a small study, taking a special broccoli seed extract once slightly lowered the lower number (diastolic) of blood pressure but did not affect the top number (systolic).
More research is needed to confirm these results.

Browse 1 study

Clinical trialSulforaphane Bioavailability and Effects on Blood Pressure in Women with Pregnancy Hypertension2021n=12

In healthy and preeclamptic women, sulforaphane showed acceptable bioavailability, informing future trials for pregnancy hypertension.

Population: Women
Participants: 12

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Vitamin B9 (Folate)View supplement →

Reconsider purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceHighTrustMedium

Evidence Review

Research shows that taking folic acid alone during pregnancy does not lower the chance of developing high blood pressure caused by pregnancy (called gestational hypertension).
However, taking folic acid as part of a multivitamin may help reduce the risk of a related pregnancy condition called preeclampsia, which can be more serious.
This may be because other vitamins in the multivitamin work together with folic acid to protect the pregnancy.
High doses of folic acid later in pregnancy do not prevent these problems in women at high risk.

Browse 3 studies2 meta-analyses

MetaMaternal folic acid supplementation for the prevention of preeclampsia: A systematic review and meta-analysis2018

A meta-analysis of 8 observational studies found maternal folic acid supplementation associated with 22% lower preeclampsia odds (OR 0.78), though evidence quality was low.

Effect: Benefit
Population: Pregnant women

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MetaEffect of folic acid supplementation during pregnancy on gestational hypertension/preeclampsia: A systematic review and meta-analysis2016

A meta-analysis of 13 studies found folic acid reduced gestational hypertension/preeclampsia in RCTs (RR 0.62) but not in cohort studies; overall benefit remains uncertain.

Effect: No Benefit
Population: Pregnant women

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Clinical trialFolic acid supplementation during early pregnancy and the risk of gestational hypertension and preeclampsia2013n=554

In 193,554 Chinese pregnant women, daily 400 µg folic acid alone in early pregnancy did not prevent gestational hypertension or preeclampsia and may have slightly increased risk.

Effect: No Benefit
Dose: 400 mcg/day
Population: Women
Participants: 554

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SeleniumView supplement →

Do not purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceLowTrustMedium

Evidence Review

It is unclear if taking selenium during pregnancy can prevent high blood pressure caused by pregnancy.
A small study found that drinking a selenium-containing supplement for 6 to 8 weeks seemed to lower the chance of developing this condition compared to a placebo.

Browse 1 study

RCTSelenium supplement in the prevention of pregnancy induced hypertension1994

In 52 high-risk pregnant women, selenium 100 mcg/day for 6–8 weeks did not reduce pregnancy-induced hypertension versus placebo.

Effect: No Benefit
Duration: 6–8 weeks
Dose: 100 mcg/day
Population: Women

View on PubMed

Black TeaView supplement →

Do not purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceLowTrustLow

Evidence Review

It is unclear whether drinking black tea during pregnancy affects the risk of pregnancy-related high blood pressure.
One study found that pregnant people who drank tea during pregnancy had a higher chance of developing pregnancy-induced high blood pressure, gestational hypertension, and early preeclampsia.
Drinking tea earlier or later in pregnancy seemed to affect these risks differently.
The risk was higher if tea drinking started during pregnancy rather than before, and it was higher among pregnant people who were overweight or expecting multiples.
Black tea was linked to higher risks than green or herbal tea.
However, this study looked at Chinese adults and was based on reviewing medical records, so the results might not apply to everyone.

Browse 1 study

ObservationalThe association between maternal tea consumption and the risk of pregnancy induced hypertension: A retrospective cohort study in Lanzhou, China2022n=10,452

In 10,452 Chinese pregnant women, tea consumption during pregnancy was associated with higher odds of pregnancy-induced hypertension (OR 1.44), gestational hypertension (OR 1.86), and early-onset preeclampsia (OR 2.93), especially black tea.

Effect: No Benefit
Population: Women
Participants: 10,452

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Evidence visualised

Same ratings as above, aggregated so you can see coverage and imbalance.

Purchase-guidance distribution

How many supplements fall in each purchase band

Effect-size distribution

How large the reported benefits tend to be

Study distribution across 5 supplements for pregnancy-induced hypertension (9 studies total).
Supplement	DEX	Studies	Meta-analyses	Share
Vitamin B9 (Folate)	★★★★★40%	3	2	33%
Vitamin D	★★★★★48%	3	0	33%
Black Tea	★★★★★28%	1	0	11%
Selenium	★★★★★32%	1	0	11%
Sulforaphane	★★★★★40%	1	0	11%

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Pregnancy-induced high-blood-pressure

Overview

Effect graph

Relevant supplements

Studies

Evidence visualised

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