Higher dose docosahexaenoic acid supplementation during pregnancy and early preterm birth: A randomised, double-blind, adaptive-design superiority trial.
Level 2 - randomized trial
Randomized, double-blind, adaptive-design superiority trial
PubMed 34308309 · doi:10.1016/j.eclinm.2021.100905
What was done
A multicentre, double-blind, adaptive-design superiority trial conducted at three US medical centres evaluated whether 1000 mg/day docosahexaenoic acid (DHA) is superior to standard 200 mg/day. A total of 1100 women with singleton pregnancies (12 to 20 weeks gestation) were enrolled and randomised (576 to 1000 mg, 524 to 200 mg) using response-adaptive allocation favoring the better-performing dose. The primary outcome was early preterm birth (EPB, <34 weeks gestation) analysed overall and stratified by enrolment DHA status (low vs. high) using Bayesian posterior probabilities (pp) in an intention-to-treat analysis (1032 analyzed: 540 in 1000 mg, 492 in 200 mg).
What was found
The 1000 mg dose had a lower EPB rate than the 200 mg dose [1.7% (9/540) vs 2.4% (12/492), pp = 0.81], driven primarily by participants with low DHA status at enrolment [2.0% (5/249) vs 4.1% (9/219), pp = 0.93]. Participants with high enrolment DHA status showed no dose-response benefit [1000 mg: 1.4% (4/289) vs 200 mg: 1.1% (3/271), pp = 0.57]. The 1000 mg dose was also associated with fewer maternal serious adverse events (chorioamnionitis, premature rupture of membranes, pyelonephritis) and neonatal serious adverse events (feeding, genitourinary, and neurologic problems; all pp > 0.90).
Why it matters
Standard prenatal vitamins typically provide only 200 mg of DHA. This trial suggests that targeted higher-dose DHA supplementation (1000 mg/day) reduces the incidence of early preterm birth and related complications in pregnant women with low baseline DHA levels.
Limits
The trial took place at only three US medical centres. The overall reduction across all participants without stratification had modest probability (pp = 0.81), indicating benefit relies heavily on baseline DHA status, but practical clinical implementation requires DHA screening capability that may not be widely available.
Cited by
- supports Susan Carlson's trial from the University of Kansas found that DHA supplementation in pregnancy reduced preterm birth and decreased the risk of other adverse delivery outcomes.