Omega 3 DHA Reduces Preterm Birth

One major cause of lifelong mental and physical disabilities in the UK – and the single biggest cause of neonatal death and illness is preterm birth.

This was emphasised in a recent House of Lords report: ‘Preterm birth: reducing risks and improving lives’ (Committee, 2024).

In 2023, one in 12 of all births in England were preterm (24-36 weeks).

The UK Government’s response (GOV.UK, 2025) to this report stated: ‘the prediction and prevention of preterm birth is challenging due to the wide range of factors that contribute to a woman’s individual risk, and many women who have preterm births do not have apparent risk factors.’

While this is true, one significant, and easily modifiable, risk factor for preterm birth – if it is screened for - is low maternal omega-3 LC-PUFA status.

What does the evidence say?

A 10-fold increased risk for early preterm birth in the lowest quintile for plasma levels of omega-3 LC-PUFA, and an almost 3-fold risk for the lowest 2 quintiles vs the upper 3 was found in Danish women. (Olsen et al., 2018)

The fact that both the House of Lords report, and the recently revised NICE guidelines for nutrition in pregnancy (NICE, 2025) fail to mention this evidence represents a huge missed opportunity to reduce the huge burden of preterm birth complications and consequences for the children and families affected, and their serious impact on the NHS, schools, wider society and the economy (which the report did document).

What’s more, highest-quality scientific evidence shows that increasing omega-3 intake during pregnancy reduces preterm birth.

'Gold-standard' Research & Expert Consensus

Over 6 years ago, a rigorous systematic review of 70 randomised controlled trials (a design considered the ‘gold standard’ scientific evidence for determining cause and effect), involving almost 20,000 women, confirmed that supplementation during pregnancy with

omega-3 EPA/DHA reduces preterm birth, even when this is only started at around the 20th week. (Middleton et al., 2018)

Since then, further such trials have confirmed this; including a 50% reduction in early pre-term birth (from 4.1 to 2%) achieved by DHA

supplementation in one carefully designed US study. (Carlson et al., 2021)

These are striking benefits – as early preterm births have the highest risk of serious adverse outcomes.

Importantly, however, high doses (1000 mg/day of DHA) are needed to achieve these benefits for women who don’t meet dietary guidelines for fish and seafood, or use fortified foods or supplements (i.e. the majority of UK women of childbearing age).

These findings, together with those from other systematic reviews, informed a consensus statement from the world’s leading independent scientific experts in this area, published 3 years ago. (Best et al., 2022).

Currently, most standard pregnancy supplements provide only around 200 mg/day DHA - as in the US and Canada, where a recent study noted the mismatch between recommended supplements and the latest evidence for pregnancy needs to prevent preterm birth and other obstetric complications (Scourboutakos et al., 2024).

Clinical Practice Guidelines recognise the role of LC-PUFA

Early last year, detailed clinical practice guidelines were published, developed by the world’s leading academic and clinical experts, along with several medical-scientific organizations. (Cetin et al., 2024).

These spell out clearly how a combination of very simple and low-cost primary care screening of omega-3 DHA intake in pregnant women - via a brief, validated questionnaire (Christifano et al., 2023) followed by targeted supplementation at the required dosage, can significantly reduce preterm births; and this approach is now being put into practice by some health authorities in Australia.

Clear Savings for Health Services

Very importantly, studies in Australia (Ahmed et al., 2015) and the US (Shireman et al., 2016) have shown that the benefits of omega-3 LC-PUFA supplementation in pregnancy would lead to significant cost savings even in the very short-term, i.e. immediate hospital

costs associated with preterm birth and other obstetric complications.

Given the impact on lifelong disabilities of reducing these, huge savings could be expected in the longer-term.

If the UK government is serious about achieving better prevention of long-term health conditions, then implementing evidence-based guidelines to reduce preterm births via screening and supplementation as necessary (Cetin et al., 2024) makes obvious sense.

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What about vegetarians & vegans?

The essentiality of omega-3 DHA in pregnancy is still not highlighted at all in NHS pregnancy guidelines for vegans and vegetarians (NHS, 2025c) which is of particular concern.

Unless provided by supplements or fortified foods, strict vegan diets contain no preformed DHA at all, and vegetarian diets very little.

Updating these guidelines too could improve both pregnancy outcomes and maternal health and wellbeing among these important minority subgroups.

Whilst plant-sources of omega 3 do exist (flax, chia, walnut etc) these do not contain the long-chain omega 3s referred to here. They contain the short-chain omega 3, known as ALA, which is usually poorly converted in humans into the biologically essential .

While vegetarian diets can – if very well-planned - provide adequate intakes of all essential nutrients, vegan diets require the use of supplements or fortified foods to achieve sufficient intakes of B12 and omega-3 DHA as a minimum, as well as very good nutritional knowledge and careful planning to avoid deficiencies of many other essential nutrients.

How does this relate to public health?

A large proportion of pregnancies are unplanned - around 45% of pregnancies and 1/3 of births in England in 2018 (Health Matters: Reproductive Health and Pregnancy Planning - GOV.UK, 2018).

Thus, effective policies to improve nutritional status before and during pregnancy must start at the population level.

Public health campaigns and training of health professionals (of every level and discipline) are needed to help improve awareness of the importance of good nutrition before conception, as well as during pregnancy, particularly if it could prevent preterm birth and the devestating impact this has on families. 

All such efforts will also need to be backed by other policies to improve access to healthier foods or supplements where needed, and particularly to reach some of the groups most vulnerable to malnutrition though food insecurity and/or other issues.

Why are the food sources are important?

Whilst supplementation has its role, nutrients are always best obtained from food and diet when possible.

Fish and seafood are not just the primary dietary source of omega-3 LC-PUFA; they also provide a wide range of other essential nutrients that are often lacking from the diets of UK women before and during pregnancy, but essential for supporting maternal health and child developmental outcomes - such as iodine, choline, selenium, zinc, B vitamins, and Vitamin D.

The government’s response to the House of Lords report on preterm birth stated: ‘We agree that all women and their partners should have timely access to information and advice regarding pregnancy planning and preconception health’.

To this end, they would do well to push for rapid revision and evidence-based updates to both current NHS guidelines for nutrition in pregnancy, (NICE, 2025) and the Eatwell guide outline for the general population (NHS, 2025a) – because as they stand, these contain little to promote fish and seafood consumption by women before and during pregnancy, and much that is likely to discourage this – by heavily emphasising potential risks, rather than benefits.

In both, fish is listed only as one of many possible sources of ‘protein’, with no mention made of omega-3 fats. US dietary guidelines do the same, and research there has suggested this may “limit a more complete understanding of its nutrient benefits beyond

protein” (Tlusty, 2021).

The Eatwell Guide does acknowledge - but only in a lower-level section (NHS, 2025b) - that the long-chain omega-3 in fish and seafood are important for heart health, and for women who are pregnant and breastfeeding.

Evidence of harm from fish & seafood?

UK advice for pregnancy is still to limit intake to 2 portions a week, citing possible risks from mercury and other contaminants that might harm the unborn child, despite there being no evidence to support this fear.

Higher fish and seafood intakes in pregnancy have repeatedly been shown to benefit child neurodevelopment – even at levels 10 x the typical US or UK intakes (Hibbeln et al., 2007, 2019).

Detailed examination of UK birth cohort data, controlling for maternal mercury levels (and multiple other relevant variables), showed

children’s IQ scores were more than 6 points higher if their mothers ate fish in pregnancy – a difference of huge educational, social and economic significance. (Golding et al., 2022).