Is it safe to take fish oil supplements in pregnancy?

Sarah Schenker


Yes and no. There are two types of fish oil supplement. One is safe to take in pregnancy, and one isn't:
  • Supplements made from the body of fish, often called omega-3 supplements, are safe to take in pregnancy.
  • Supplements made from the liver of fish, such as cod liver oil, are not safe to take in pregnancy.

Both types of fish oil supplements contain beneficial long-chain omega-3 fatty acids, which help your baby's brain and eyes to develop. In the long-term, they may also help to protect you against heart disease.

However, cod liver oil also contains high levels of the retinol form of vitamin A. You shouldn't take supplements containing the retinol form of vitamin A when you're pregnant, because large amounts of retinol can harm your baby.

There's no official recommendation that pregnant women should take a fish oil supplement. Some research suggests that babies born to women taking omega-3 long-chain fatty acids weigh a little more and are less likely to be born early, but more research needs to be carried out to be sure.

If you eat some oily fish every week, you probably won't need to take a supplement. Government advice is that we should all eat more fish, and up to two portions a week can be oily fish. Oily fish will provide you with plenty of omega-3 fatty acids, as well as other vitamins, minerals, and protein that you wouldn't get from taking just a supplement.

Some research has shown that in countries where pregnant women tend to eat more fish, fewer develop pre-eclampsia, or have a baby who is premature, or a low birth weight.

Fish that are rich in omega-3 fatty acids include mackerel, salmon, trout, kippers, anchovies, and sardines.

Fresh tuna also counts as an oily fish, but tinned tuna doesn't, as the canning process depletes the oils.

Crab and prawns contain reasonable amounts of omega-3 fats. And white fish, such as cod and haddock, contain some omega-3, but in lower amounts. Some foods made with white fish have extra omega-3 added.

Although oily fish is good for you, don't have more than two portions a week while you're pregnant. Oily fish can also contain environmental pollutants, such as dioxins and polychlorinated biphenyls (PCBs).

Dioxins and PCBs can build up in your body over a long period of time. There's some evidence that they may interfere with your unborn baby's development.

One or two portions of oily fish a week will benefit you and your developing baby at a level that doesn't cause harm from the pollutants in the fish.

If you don't eat fish, and decide to take a fish oil supplement, make sure that the supplement you take is suitable for pregnant women.

Avoid high-dose supplements and check how much DHA and EPA they contain. These are the two beneficial long-chain omega-3 fats found in oily fish. About 450mg EPA and DHA a day is equal to eating one or two portions of oily fish a week. If you don't want to eat fish oil, but would like to take a supplement containing long-chain omega-3 (EPA and DHA), you can buy supplements derived from algae. Fish get their omega-3 from algae.

If you're at all unsure about which supplement to take, ask the pharmacist for advice.

Last reviewed: July 2013

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