The daily goal for total omega-3 fatty acids during pregnancy is about 650 mg, with at least 300 mg from DHA and roughly 350 mg from EPA. Most prenatal guidance focuses on DHA because of its direct role in fetal brain development, but EPA plays its own critical part in a healthy pregnancy, and skipping it can create problems.
Why EPA Matters Alongside DHA
DHA gets most of the attention in prenatal nutrition because it accumulates in the fetal brain and retina. EPA does something different: it produces signaling molecules that help relax the uterine muscle, support placental function, and regulate inflammation. These effects directly influence how long a pregnancy lasts and how well the placenta delivers nutrients.
When EPA intake is too low relative to other fatty acids, the balance of inflammatory signals can shift in a direction that promotes preterm labor and preeclampsia. A study of pregnant women in Indonesia found that those with low blood levels of EPA had dramatically higher odds of delivering preterm. A large Cochrane review of clinical trials confirmed that fish oil supplementation, which provides both EPA and DHA, reduces the risk of preterm and early preterm birth while increasing birth weight and gestational length.
Only about 4% to 11% of DHA converts back into EPA in your body. That means taking a DHA-only supplement likely won’t give you enough EPA to produce those protective signaling molecules. It may also limit how efficiently DHA itself gets transported into fetal cells.
How Much EPA to Aim For
There is no official upper or lower limit set specifically for EPA during pregnancy. The NIH notes that formal intake recommendations for EPA and DHA individually have not been established. However, expert consensus points to a combined target of about 650 mg of omega-3s per day, with 300 mg as DHA. That leaves roughly 350 mg for EPA.
On the safety side, a 2024 clinical practice guideline concluded that intakes up to 1,000 mg per day of DHA or DHA plus EPA do not raise safety concerns during pregnancy. Omega-3 fatty acids have no established upper limit for toxicity. Clinical trials have safely used doses as high as 2,200 mg DHA plus 1,100 mg EPA daily from mid-pregnancy through delivery, though those doses are well above what most women need from routine supplementation.
What Two Servings of Fish Actually Provide
Both ACOG and the FDA recommend eating two 6-ounce servings of low-mercury fish per week during pregnancy. This gets you roughly 100 to 250 mg of total omega-3s per day and about 50 to 100 mg of DHA. That leaves a significant gap between what you’re eating and the 650 mg target.
Here’s what common low-mercury fish deliver per 6-ounce serving (total omega-3s, with DHA in parentheses):
- Sardines: 2,200 mg (1,200 mg DHA)
- Shrimp: 880 mg (320 mg DHA)
- Scallops: 740 mg (360 mg DHA)
- Salmon: 620 mg (260 mg DHA)
- Pollock: 520 mg (360 mg DHA)
- Light tuna: 380 mg (170 mg DHA)
- Catfish: 340 mg (180 mg DHA)
If you eat two servings of fish a week, you’ll typically need an additional 400 to 550 mg of omega-3s from supplements, with about 225 mg of that as DHA. The rest would come as EPA. If you eat little or no fish, your supplement needs are higher.
Choosing a Supplement With the Right Ratio
Many prenatal vitamins contain only DHA, or contain so little EPA that it barely registers. This is a problem. Data on pregnancy outcomes from DHA alone, without any EPA, are limited, and the biological case for including EPA is strong. Look at the supplement facts panel for both numbers.
A reasonable EPA-to-DHA ratio in a prenatal omega-3 supplement falls somewhere around 1:1 to 1:2 (one part EPA to two parts DHA). Clinical trials in pregnant women have commonly used a 1:2 ratio. The total daily goal from diet plus supplements should land around 650 mg of combined EPA and DHA, though going somewhat higher is not a concern.
Fish oil capsules provide both EPA and DHA. Algae-based supplements, which are free of mercury and suitable for vegetarians, have traditionally supplied only DHA with no EPA. Newer algae products have started to include EPA, so check the label carefully. If your algae supplement has zero EPA, you’re relying entirely on backward conversion from DHA, which is inefficient at best.
When to Start
Starting omega-3 supplementation in the first trimester appears to offer measurable benefits for fetal growth. A study following a racially diverse group of pregnant women found that first-trimester EPA and DHA supplementation was associated with larger estimated fetal weight and greater abdominal circumference in the second and third trimesters. Women who relied on dietary sources alone without supplements saw smaller effects, limited mainly to head measurements late in pregnancy.
This suggests that earlier is better. If you’re planning a pregnancy or just learned you’re pregnant, that’s a good time to check whether your prenatal supplement includes both EPA and DHA, and whether the combined amount gets you close to the 650 mg daily target when paired with your fish intake.