Maternal DHA supplementation and early preterm birth

3 min read /
General Nutrition Obstetrics / Gynaecology Public health
Maternal DHA supplementation and early preterm birth

Omega-3 fatty acids, including docosahexaenoic acid (DHA) has been associated with reduced incidence of early preterm birth (<34 weeks) while the dose of DHA required is obscure. This study was conducted to examine the hypothesis that 1,000 mg DHA daily would be superior to 200 mg daily, a level in most prenatal supplements.

Study design

  • Randomized, multicenter, double-blinded, adaptive-design, superiority trial conducted in USA

Subjects and Intervention

1,100 women with singleton pregnancies and 12 to 20 weeks gestation were randomized into:

  • 1,000 mg/day DHA group (n = 576)
  • 200 mg/day DHA group (n = 524)



  • Effect of DHA on early preterm birth


  • Preterm birth (<37 weeks)
  • Maternal DHA status (red blood cell phospholipid DHA) at enrollment and delivery
  • Neonate DHA status
  • Very low birth weight (<1,500 g)
  • Low birth weight (<2,500 g), etc.


1,000 mg/day group showed a lower rate of early preterm birth as compared with 200 mg/day group [1.7% (9/540) vs. 2.4% (12/492), pp = 0.81]

  • Especially, if the women had low DHA status at enrollment [2.0% (5/249) vs. 4.1% (9/219), posterior probability (pp) = 0.93]

A dose effect was not noted among women with high DHA status (pp = 0.57)

  • 1,000 mg/day: 1.4% (4/289)
  • 200 mg/day: 1.1% (3/271)

The higher dose (1,000 mg/day) was associated with fewer serious adverse events (all pp > 0.90)

  • Maternal: Chorioamnionitis, premature rupture of membranes and pyelonephritis
  • Neonatal: Feeding, genitourinary and neurologic problems


  • Clinicians could consider prescribing 1,000 mg/day DHA during pregnancy to reduce early preterm birth in women with low DHA status if screening for DHA status is possible

Link to publication:



Carlson SE et al. Higher dose docosahexaenoic acid supplementation during pregnancy and early preterm birth: A randomised, double-blind, adaptive-design superiority trial. EClinicalMedicine 2021.

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