What's the Best DHA Supplement for Pregnancy?

If you are pregnant or planning to be, you have probably already encountered the advice to take a DHA supplement. The recommendation is straightforward enough. The confusion starts when you try to pick one: fish oil capsules that might contain mercury, algae oils with wildly different DHA concentrations, and labels that tell you very little about what is actually inside.

DHA is a long-chain omega-3 fatty acid that your body cannot manufacture efficiently on its own. During pregnancy, your baby draws on your DHA stores for brain and eye development, which means your own levels drop unless you are actively replacing them. The question is not whether you need DHA. It is which source gives you a clean, reliable dose without the contamination risks that come with marine-sourced options.

We manufacture an algae-derived DHA supplement, so we have a direct interest in this question. When we reviewed the contamination testing data on commercial fish oil and algae oil products side by side, the differences in purity profiles were striking. We have aimed to present both options honestly, including where fish oil has a genuine advantage we cannot match in a single product.

Why DHA Matters During Pregnancy

EFSA-Authorised DHA Health Claims for Pregnancy

DHA contributes to the maintenance of normal brain function and the maintenance of normal vision. These are health claims authorised by EFSA under Regulation (EU) No 432/2012, at a daily intake of 250 mg of DHA.

Maternal intake of DHA also contributes to the normal brain development and eye development of the foetus and breastfed infants, at a daily intake of 200 mg DHA in addition to the recommended 250 mg EPA and DHA for adults.

How DHA Depletion Affects You During Pregnancy

Your baby's brain undergoes its most rapid growth in the third trimester. If you are not getting enough DHA through your diet or supplements, your body will prioritise the baby, potentially leaving you depleted. Many women notice the effects as brain fog, fatigue, or difficulty concentrating postpartum. Replenishing those stores takes months.

You will sometimes see claims that DHA supplementation produces measurably higher IQ scores in infants. The research here is mixed. Some studies show modest benefits in visual acuity and attention in early infancy, but long-term cognitive advantages have not been consistently demonstrated. What is well-established is that adequate DHA during pregnancy supports normal neural and visual development.

Fish Oil vs Algae Oil for Pregnancy DHA

The Contamination Question with Fish Oil

Traditionally, fish oil was the go-to source of DHA. Oily fish like salmon, mackerel, and sardines are naturally rich in long-chain omega-3s. The problem is that ocean-caught fish accumulate environmental contaminants including mercury, PCBs, and dioxins. During pregnancy, you are advised to limit certain fish for exactly this reason.

Fish oil supplements are purified to remove contaminants, and reputable brands test for heavy metals. But if you are someone who checks labels carefully, especially during pregnancy, not every brand publishes third-party testing results.

Why Algae Oil Avoids the Contamination Problem

Algae oil takes a different route. Microalgae are where fish get their omega-3s in the first place. By cultivating algae in controlled, closed-system bioreactors, producers create DHA oil that never enters the marine food chain. No mercury accumulation, no bycatch, no reliance on wild fish stocks.

The trade-off is real, though. Most algae oils are DHA-dominant, meaning they provide very little EPA. Fish oil gives you both EPA and DHA in a single capsule. If your midwife or GP has specifically recommended EPA alongside DHA, you will need to check whether an algae-only product meets that requirement, or consider combining it with an EPA-rich source like phytoplankton.

What to Look for in a Prenatal DHA Supplement

DHA Dose, Purity, and Freshness

DHA dose per capsule. You need at least 200 mg of DHA daily during pregnancy on top of your background omega-3 intake. Many products advertise total omega-3 content on the front label, but the DHA breakdown is on the back. Check it.

Contaminant testing. Look for brands that publish third-party lab results for heavy metals, PCBs, and oxidation markers. If the brand does not mention testing at all, that is a signal worth heeding.

Oxidation and freshness. Omega-3 oils go rancid. Rancid fish oil capsules are the cause of those fish burps people complain about. Algae oil produced in closed systems and tested for oxidation markers (TOTOX values) tends to be more stable, but check the production method and expiry date regardless.

Extraction Method and Allergens

Source and extraction method. Some algae oils use hexane solvent extraction. Others use supercritical CO2 or solvent-free methods. If this matters to you during pregnancy, the information should be available on the brand's website.

Allergens. If you have allergies to soy, shellfish, or tree nuts, check the capsule shell and carrier oils. Some DHA supplements use soy lecithin as an emulsifier.

ALA from Flaxseed Is Not a Substitute for Prenatal DHA

You might have read that flaxseed, chia seeds, and walnuts are good omega-3 sources. They are, but only for ALA (alpha-linolenic acid), a short-chain omega-3. Your body can convert ALA to EPA and DHA, but the conversion rate for DHA is typically below 5 per cent. During pregnancy, this is not enough to meet your needs.

These foods are excellent for other nutritional reasons, but they will not replace a direct DHA source. That is not a criticism of flaxseed. It is a limitation of human enzyme pathways.

Where Phytality Clean Omega Fits In

Disclosure: Phytality is the publisher of this article and the manufacturer of Clean Omega. We present our product alongside its limitations below.

We developed Clean Omega specifically to address the concerns that come up most often when pregnant women look for a DHA supplement: contamination risk, ingredient transparency, and getting a meaningful dose without multiple capsules. The formulation uses Schizochytrium, a naturally DHA-rich microalgae strain, produced with solvent-free extraction in a closed bioreactor system.

Each capsule provides 250 mg of DHA. At two capsules daily, you reach 500 mg, which comfortably meets the EFSA-supported daily intake for both general DHA maintenance and the additional maternal-specific claim. The product is certified vegan, and we publish third-party lab testing results covering heavy metals, oxidation, and microbial contamination.

What Clean Omega does not do: it provides DHA but not meaningful levels of EPA. If your healthcare provider has recommended combined EPA and DHA supplementation, Clean Omega alone will not cover both. You would need to pair it with an EPA source like ULTANA Phytoplankton. We will not pretend one product does everything.

How and When to Take DHA During Pregnancy

Start as early as you can. Ideally, you would begin DHA supplementation before conception or during the first trimester. The neural tube forms within the first four weeks, and DHA is incorporated into brain tissue from early development onwards. If you are already in your second or third trimester and have not been supplementing, starting now still supports the period of most rapid brain growth.

Take your DHA with a meal that contains some fat. Omega-3 fatty acids are fat-soluble, so absorption improves when you take them alongside food rather than on an empty stomach. If you find capsules hard to swallow during periods of morning sickness, try taking them with your evening meal instead.

Continue through breastfeeding if you can. Your baby continues to need DHA for brain development after birth, and breast milk DHA levels reflect your own intake.

DHA in Pregnancy FAQ

How much DHA should you take during pregnancy?

The EFSA-authorised maternal claim requires 200 mg DHA daily on top of 250 mg combined EPA+DHA for adults. In practice, most prenatal guidelines suggest 200 to 500 mg of DHA daily. Your midwife or GP can advise on the right dose for your situation.

Can you take too much DHA?

EFSA considers long-term intake of up to 1 g of DHA daily (or up to 5 g of combined EPA and DHA) to be safe for the general adult population. At typical prenatal doses of 200 to 500 mg, you are well within that range. If you are combining multiple omega-3 products, add up the total across everything you are taking.

Is it too late to start DHA in the third trimester?

No. The third trimester is when your baby's brain grows most rapidly and DHA accumulation is at its highest rate. Starting supplementation at any point during pregnancy is better than not supplementing at all.

Do you need to continue DHA while breastfeeding?

Yes, if you want to maintain your own stores and pass DHA to your baby through breast milk. The EFSA maternal claim covers both pregnancy and breastfeeding. If you stop supplementing after birth, your levels may remain low for months.

Is algae oil as effective as fish oil for DHA?

Algae oil provides the same DHA molecule as fish oil, and studies on algae-derived DHA show comparable bioavailability. The difference is in what else comes with it: fish oil provides both EPA and DHA, while most algae oils are DHA-dominant. For DHA specifically, algae oil is equivalent.

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult your GP or a qualified healthcare professional before starting any supplement, particularly during pregnancy.

Methodology and Disclosure

Phytality manufactures the Clean Omega and ULTANA Phytoplankton products mentioned in this article. Where we assess our own product, we have stated both its strengths and its limitations, including EPA content and price positioning. Health claims about DHA's contribution to brain function, vision, and maternal/foetal development are authorised by EFSA under Regulation (EU) No 432/2012 and Commission Regulation (EU) No 440/2011. Intake conditions are stated where they apply.

General nutrition science about omega-3 metabolism (ALA conversion rates, DHA as a structural component of brain tissue) reflects established biochemistry. Comparisons between algae oil and fish oil reflect our editorial assessment. This content does not constitute medical advice. Always consult your midwife, GP, or healthcare provider before starting any supplement during pregnancy.

Last reviewed: April 2026