Most health organizations recommend pregnant women get at least 200 mg of DHA per day, with a combined total of about 650 mg of omega-3 fatty acids (DHA plus EPA). Women who are low in omega-3s may benefit from higher amounts, closer to 1,000 mg of combined DHA and EPA daily, to reduce the risk of preterm birth. These numbers can feel confusing because different guidelines emphasize different goals, so here’s how it all breaks down.
The Baseline: 200 to 300 mg of DHA Daily
International nutrition advisories consistently agree that pregnant women need a minimum of about 200 mg of DHA each day. This is the floor for supporting fetal brain and eye development. Some guidelines set the combined omega-3 target at 650 mg per day, with at least 300 mg coming specifically from DHA. The remaining 350 mg can come from EPA or other long-chain omega-3s.
Most prenatal vitamins contain DHA, but the amount varies widely. Some provide only 100 to 200 mg, which may fall short depending on how much fish you eat. If your prenatal doesn’t list a DHA amount on the label, it likely contains very little or none at all.
The Higher Target: 1,000 mg for Preterm Birth Prevention
A statement from the International Society for the Study of Fatty Acids and Lipids (ISSFAL) recommends that women with low omega-3 levels take about 1,000 mg of combined EPA and DHA daily, ideally starting before 20 weeks of pregnancy. This higher dose is specifically aimed at reducing the risk of early birth. A large trial published in the New England Journal of Medicine used a dose of roughly 800 mg DHA and 100 mg EPA per day and found meaningful reductions in preterm delivery.
The key detail: women who already have adequate omega-3 intake don’t necessarily need this higher dose. The biggest benefit goes to those starting from a low baseline. If you regularly eat fatty fish two to three times a week, you may already be in a good range. If you rarely eat seafood, the higher target is worth discussing with your provider.
Why DHA Matters More Than EPA for the Baby
DHA is the omega-3 that accumulates most heavily in fetal brain and retinal tissue. This accumulation happens throughout pregnancy but accelerates dramatically from about week 29 through delivery. During this window, DHA supports the formation of new neurons, the connections between them, and the signaling systems that underpin learning and memory. It also plays a direct role in visual development. One study found that 600 mg of DHA per day improved visual acuity in newborns.
EPA plays a supporting role in reducing inflammation and supporting maternal cardiovascular health, but it doesn’t concentrate in fetal brain tissue the way DHA does. This is why most pregnancy-specific supplements are weighted toward DHA. A ratio of roughly 2:1 or higher (DHA to EPA) is common in prenatal omega-3 products, though no single ratio has been proven superior in clinical trials.
When to Start Supplementing
Earlier is better. Research tracking fetal growth found that women who began DHA and EPA supplementation in the first trimester had measurable differences in fetal growth patterns compared to those who did not, including more proportional growth between the head and abdomen through the second and third trimesters. For preterm birth prevention specifically, supplementation should begin before 20 weeks to be most effective.
If you’re already past that window, starting later still supports the third-trimester brain development surge. DHA continues accumulating in fetal brain tissue right up until delivery, so there’s no point at which it’s “too late” to begin.
Best Food Sources During Pregnancy
Two to three servings per week of low-mercury fish can supply a significant portion of your omega-3 needs. Salmon and herring are among the best options, providing high DHA and EPA with low mercury levels. Canned skipjack tuna (labeled “chunk light”) is another safe choice, though it provides less omega-3, roughly 230 mg per three-ounce serving.
Fish to avoid entirely during pregnancy include shark, swordfish, king mackerel, tilefish, and orange roughy. These larger, predatory species accumulate mercury at levels that can harm fetal brain development. The FDA maintains a classification system of “best choice,” “good choice,” and “choices to avoid” that can guide your selections at the grocery store.
Even with regular fish intake, many women fall short of 300 mg of DHA per day from food alone. Depending on the omega-3 content of the fish you eat in a given week, you may still need an additional 400 to 550 mg of combined EPA and DHA from a supplement, with about 225 mg of that coming from DHA.
Algal Oil for Vegetarians and Vegans
If you don’t eat fish, algal oil (derived from microalgae) is the primary plant-based source of preformed DHA and EPA. A randomized, double-blind clinical trial comparing microalgal oil to fish oil found that DHA and EPA from algal supplements were statistically equivalent in absorption when measured in blood levels over 14 weeks. This makes algal oil a reliable alternative, not a compromise.
Algal oil supplements typically emphasize DHA, with some newer formulations also including EPA. Check the label to confirm the DHA content meets at least 200 to 300 mg per dose. Plant sources like flaxseed and chia seeds provide a precursor omega-3 (ALA), but the body converts very little of it into DHA, making these foods insufficient as a primary source during pregnancy.
Upper Limits and Safety
The European Food Safety Authority considers up to 5,000 mg of combined EPA and DHA per day safe, including for pregnant women. In clinical trials, doses up to 2,700 mg per day were well tolerated with no increase in bleeding episodes. A practical upper limit of 2,700 mg per day is a reasonable ceiling to stay under.
Concerns about omega-3s causing bleeding are largely theoretical at standard supplementation doses. A large Cochrane meta-analysis found no increased bleeding risk, though two cardiovascular trials using very high EPA doses did find a tiny increase in bleeding events (0.1% more per year). At the doses relevant to pregnancy, typically 500 to 1,000 mg per day, this is not a meaningful concern.
Quick Reference for Daily Targets
- Minimum DHA for fetal development: 200 to 300 mg
- Combined EPA and DHA for general pregnancy health: 650 mg
- Combined EPA and DHA for preterm birth prevention (low omega-3 status): 1,000 mg, started before 20 weeks
- Practical upper limit: 2,700 mg combined EPA and DHA
If you’re choosing a supplement, look at the “Supplement Facts” panel for the individual DHA and EPA amounts rather than the total fish oil content. A 1,000 mg fish oil capsule often contains only 300 mg of combined DHA and EPA, meaning you’d need multiple capsules to hit the targets above.