Omega-3 fatty acid supplementation to prevent recurrent preterm birth: a randomized controlled trial

Obstet Gynecol. 2010 Feb;115(2 Pt 1):234-42. doi: 10.1097/AOG.0b013e3181cbd60e.


Objective: To assess whether the addition of an omega-3 long-chain polyunsaturated fatty acid supplement would reduce preterm birth in women with at least one prior spontaneous preterm birth receiving 17alpha-hydroxyprogesterone caproate.

Methods: We conducted a randomized, double-masked, placebo-controlled trial in 13 centers. Women with a history of prior spontaneous singleton preterm birth and a current singleton gestation were assigned to either a daily omega-3 supplement (1,200 mg eicosapentaenoic acid and 800 mg docosahexaenoic acid) or matching placebo from 16-22 through 36 weeks of gestation. All participants received weekly intramuscular 17alpha-hydroxyprogesterone caproate (250 mg). The primary study outcome was delivery before 37 weeks of gestation. A sample size of 800 was necessary to have 80% power to detect a 30% reduction in the primary outcome from 30%, assuming a type I error two-sided of 5%.

Results: A total of 852 women were included, and none was lost to follow up. Delivery before 37 weeks of gestation occurred in 37.8% (164/434) of women in the omega-3 group and 41.6% (174/418) in the placebo group (relative risk 0.91, 95% confidence interval 0.77-1.07).

Conclusion: Omega-3 long-chain polyunsaturated fatty acid supplementation offered no benefit in reducing preterm birth among women receiving 17alpha-hydroxyprogesterone caproate who have a history of preterm delivery.

Clinical trial registration:,, NCT00135902.

Level of evidence: I.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • 17 alpha-Hydroxyprogesterone Caproate
  • Dietary Supplements*
  • Double-Blind Method
  • Fatty Acids, Omega-3 / administration & dosage*
  • Female
  • Humans
  • Hydroxyprogesterones / administration & dosage
  • Infant, Newborn
  • Injections, Intramuscular
  • Pregnancy
  • Premature Birth / prevention & control*
  • Progesterone Congeners / administration & dosage
  • Recurrence


  • Fatty Acids, Omega-3
  • Hydroxyprogesterones
  • Progesterone Congeners
  • 17 alpha-Hydroxyprogesterone Caproate

Associated data


Grant support