High Dose DHA in Pregnancy Might Reduce Risk of Early Preterm Birth

Several meta-analyses have concluded n-3 fatty acids, including docosahexaenoic acid (DHA), reduce early preterm birth (EPB, < 34 weeks), however, the amount of DHA required is unclear. Therefore, Dr Susan E Carlson and her team hypothesized that 1000 mg DHA per day would be superior to 200 mg, the amount in most prenatal supplements.

It was a randomized, multicentre, double-blind, adaptive-design, superiority trial of 1032 women with singleton pregnancies and 12 to 20 weeks gestation. They were randomly assigned to receive either high dose DHA (1000mg; n=540) or low dose DHA (200 mg; n=492). The planned adaptive design periodically generated allocation ratios favoring the better performing dose. The major outcome assessed was EPB by dose and by enrolment DHA status (low/high). The researchers determined Bayesian posterior probabilities (pp) for planned efficacy and safety outcomes using intention-to-treat.

Key findings of the study were:

• Upon analysis, the researchers found that higher dose had a lower EPB rate [1.7% (9/540) vs 2.4% (12/492)] especially if participants had low DHA status at enrolment [2.0% (5/249) vs 4.1%, (9/219)].
• They noted that the participants with high enrolment DHA status did not realize a dose-effect [1000 mg: 1.4% (4/289); 200 mg: 1.1%].
• They further found that the higher dose was associated with fewer serious adverse events (maternal: chorioamnionitis, premature rupture of membranes and pyelonephritis; neonatal: feeding, genitourinary and neurologic problems, all pp>0.90).

The authors concluded, "Clinicians could consider prescribing 1000 mg DHA daily during pregnancy to reduce EPB in women with low DHA status if they are able to screen for DHA."

For further information:

DOI: https://doi.org/10.1016/j.eclinm.2021.100905