Is fish oil safe during pregnancy?

What does the evidence say about fish oil during pregnancy?

1. Omega-3 supplements come in several forms, including fish oil, krill oil, cod liver oil, and algal oil, and pregnant women are advised to eat about 8 to 12 ounces of seafood a week, choosing options higher in EPA and DHA and lower in mercury. 1
2. Cod liver oil supplements provide vitamin A and vitamin D on top of omega-3s, and professional guidance recommends pregnant women get at least 250 mg a day of combined EPA and DHA, with roughly 100 to 200 mg a day of extra DHA suggested during pregnancy. 2
3. Omega-3 supplements lowered the rate of preterm birth before 37 weeks from 13.4% to 11.9%, and early preterm birth before 34 weeks from 4.6% to 2.7%, in a review covering 70 trials and nearly 20,000 pregnant women. 3
4. Too much preformed vitamin A during pregnancy can cause birth defects affecting a baby's eyes, skull, lungs, and heart, so anyone who is or might become pregnant is advised to skip high-dose preformed vitamin A supplements. 4
5. The tolerable upper intake level for preformed vitamin A is 3,000 mcg RAE (10,000 IU) a day for women 14 and older, including during pregnancy, and experts advise pregnant women not to go over that amount from supplements. 5

Is fish oil safe in each trimester?

• First trimester. DHA needs in the first trimester are similar to what they were before pregnancy, so there's no rush to start a new supplement if nausea makes capsules or fish unappealing. If you already take a fish oil product, check the label for its exact form, fish oil, algal oil, or cod liver oil, since that matters more than the brand name.
• Second trimester. Appetite usually improves in the second trimester, and some experts suggest 600 to 1,000 mg a day of combined EPA and DHA if your diet is low in fish, often starting around now. Many prenatal vitamins already include some DHA, so check your label before adding a separate capsule.
• Third trimester. Your baby's brain grows fastest in the third trimester, which is when steady DHA intake matters most. The sourcing rule stays the same through delivery: choose a purified fish oil or algal-oil product over plain cod liver oil, since the vitamin A concern doesn't go away as pregnancy progresses.