Does DHA in pregnancy help the baby?

The child's brain and eyes

A 2026 review included 21 randomized trials of DHA in pregnancy and pooled 19 of them.^[1] DHA did not improve the child's attention, movement, intelligence, language, executive function or short-term memory. Birth weight was 72.5 g higher, but head size, birth length and the length of pregnancy did not improve.^[1]

In the DOMInO trial, 2,399 women in Australia took 800 mg of DHA a day from fish oil, or vegetable oil, from before week 21 until birth.^[3] At 18 months, the children's cognitive and language scores did not differ between the groups.^[3] The NIH notes that trials have not shown consistent benefits for the baby's thinking or vision.^[4]

Preterm birth

A 2018 Cochrane review of 70 trials with 19,927 women looked at omega-3 fats from supplements and food.^[2]

• Birth before 37 weeks: 11.9% with omega-3 against 13.4% without.^[2]
• Birth before 34 weeks: 2.7% against 4.6%.^[2]
• Pregnancy longer than 42 weeks: 2.6% against 1.6%.^[2]

Trials of DHA alone:

• KUDOS: 350 women took 600 mg of DHA a day or placebo from before week 20. On average they took 469 mg. Pregnancy lasted 2.9 days longer, babies weighed 172 g more, and fewer babies were born before 34 weeks.^[5]
• ADORE: 1,100 women took 1000 mg or 200 mg of DHA a day. Birth before 34 weeks was 1.7% with 1000 mg and 2.4% with 200 mg. In women with low DHA at the start, it was 2.0% against 4.1%. In women with high DHA at the start, the dose made no difference.^[6] The US National Institute of Child Health and Human Development paid for the trial, and the company DSM gave the capsules of algal DHA oil.^[6]

The largest trial, ORIP, gave 900 mg of omega-3 fats from fish oil a day to women in 5,486 pregnancies, from before week 20 to week 34. Birth before 34 weeks did not differ: 2.2% against 2.0%. Very large babies were more common with omega-3.^[7]

A 2024 review of 9 trials with 5,710 women found that 450 to 800 mg of DHA a day raised birth weight by 101.7 g and lowered low birth weight. The fall in preterm birth was not statistically significant.^[8]

Who may gain the most

In ADORE, the higher dose helped mainly women with low DHA levels at the start.^[6] A guideline cited by the NIH advises 600 to 1000 mg of DHA and EPA a day for pregnant women whose DHA intake is under 150 mg a day.^[4]

Safety

KUDOS found no safety concerns.^[5] In ORIP, minor stomach upsets were more common with omega-3, and serious adverse events did not differ.^[7] Cod liver oil also contains vitamins A and D, which can be harmful in excess.^[9] Women who are pregnant should ask a doctor or pharmacist before they start a supplement.^[4]

What is still unknown

The Cochrane authors called for longer follow-up of the children, and for studies of which type, timing and dose of omega-3 work best.^[2] The 2026 review called for studies that find which women and babies respond to DHA.^[1]