What does the research say about omega-3s?
The short answer
Women taking omega-3 supplements became pregnant somewhat faster in one large study. That's a promising signal rather than proof — it watched what women chose to do.
What to know
- The women studied were 30 to 44 and had no known fertility problem.
- Eating oily fish is a reasonable alternative to a supplement.
- At higher doses it has a mild blood-thinning effect — worth mentioning before surgery or delivery.
- Choose a product tested for heavy metals and freshness.
Read the full explanation
What to do
- Eat 2–3 servings of low-mercury fish a week — 8 to 12 ounces in total, a serving being about the size of your palm. This is FDA and EPA advice for anyone who is or might become pregnant.
- If you don't eat fish, a prenatal or supplement with DHA is a reasonable alternative. International guidance suggests at least 200 mg of DHA a day in pregnancy.
| Choose | Fish |
|---|---|
| Best — 2–3 a week | Salmon, sardines, anchovies, cod, haddock, pollock, tilapia, catfish, canned light tuna |
| Good — 1 a week | Halibut, mahi mahi, snapper, albacore or yellowfin tuna, bluefish |
| Avoid | King mackerel, marlin, orange roughy, shark, swordfish, bigeye tuna, tilefish from the Gulf of Mexico |
Be careful
Safety consideration High doses — several grams a day — can increase bleeding, which matters if you take a blood thinner. Don't use cod liver oil as your omega-3 in pregnancy; it also contains vitamin A.
What the evidence is based on
A study of 900 women trying naturally found those taking omega-3 supplements conceived faster. It's observational — the women chose to take supplements and may have differed in other ways — and doses weren't recorded. The fish advice stands on its own for pregnancy regardless.
What the research shows
Is omega-3 supplementation associated with becoming pregnant faster?
The research points toward a benefit.
Who was studied. Women aged 30-44 trying to conceive without known infertility, followed prospectively.
Outcome measured. Time to pregnancy
What was found. Women taking omega-3 supplements had a higher probability of conceiving per cycle in this cohort.
Main limitation. Not randomized, so women who take supplements may differ from those who don't in other ways.
Why this rating?
Prospective cohort rather than a randomized trial, so people who take supplements may differ systematically from those who don't in ways that are hard to adjust away. Direct to a meaningful outcome, which is a strength; not randomized, which is the limitation.
Questions for your doctor
Edit any of these before you add it — they're yours. Your list stays in this browser, and you can print a one-page sheet from it.
- Is there a reason for me to take omega-3 rather than eat more fish?
- Does it affect any medication I'm on, or bleeding risk around procedures?
Sources
- FDA and EPA, Advice about eating fish
- NIH Office of Dietary Supplements, Omega-3 fatty acids fact sheet
- Stanhiser et al., Omega-3 supplementation and fecundability, Human Reproduction 2022