Prenatal Vitamins and Omega-3 (DHA)

What 2 graded rows on prenatal vitamins agree on for Omega-3 (DHA), and where they differ. Counted side by side, never averaged.

Consensus finder Rows from the Prenatal Vitamins page, reviewed Oct 21, 2026 How it decides

What the rows agree on

Each block and row is one graded row from the Prenatal Vitamins page, with its PubMed record.

Your question

Omega-3 (DHA)2

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Prenatal Vitamins and Omega-3 (DHA)

2 rows · 15,790 people

Split. 1 row found an improvement and 1 found no difference.

No difference

Improved

Each block is one evidence row, sized by how many people it enrolled, with its grade inside.

Grade B× 1
No effect× 1

Rows: 2
Trials: 27
People: 15,790; Pooled reviews may count some twice

Where they differ

From the rows

Study designWhen published

The best-graded row, grade B, is a systematic review of 10,304 people (2018) and found an improvement. 1 row is graded No effect, our grade for adequately powered trials that found no effect.

The row that found an improvement is a pooled review of several trials; the row that found no difference is a single study.

The row that found no difference is newer (2019) than the row that found an improvement (2018).

The rows

1 improved · 1 no difference

Grade BPreterm birth (omega-3 fatty acids) · Improved
Systematic review, 26 studies · n 10,304 · 2018 · Pregnant women at low, mixed or high risk in 26 RCTs (preterm outcome), mostly in upper-middle- or high-income countries
Varied across trials · Pregnancy
Preterm birth before 37 weeks was 11.9% vs 13.4% (RR 0.89, 95% CI 0.81–0.97; high-quality evidence) and early preterm birth before 34 weeks fell too (RR 0.58). Low birthweight fell slightly (RR 0.90); pregnancies past 42 weeks probably rose (RR 1.61).
Row on the Prenatal Vitamins page · PubMed 30480773 (opens PubMed)
No effectEarly preterm birth (omega-3 fatty acids) · No difference
RCT · n 5,486 · 2019 · Pregnant women at six Australian centres, enrolled before 20 weeks (5,517 women randomised)
900 mg/day omega-3 long-chain fatty acids · From before 20 weeks to 34 weeks
Early preterm delivery (before 34 weeks) was 2.2% vs 2.0% with control (adjusted RR 1.13, 95% CI 0.79–1.63). Post-term interventions and adverse events did not differ; very large-for-gestational-age babies were more common (RR 1.30), as was minor stomach upset.
Row on the Prenatal Vitamins page · PubMed 31509674 (opens PubMed)

Read onRead the full evidenceThe full evidence chapter on its page, with every outcome and its sources.