Grand Rounds

Does N-3 Long-Chain Polyunsaturated Fatty Acid Supplementation Decrease Early Preterm Births?

BACKGROUND AND PURPOSE:

Previous studies on maternal use of n-3 Long-Chain Polyunsaturated Fatty Acid Supplementation demonstrated the following
- Benefit: Reduced preterm delivery
- Risk: Postterm pregnancy
Makrides et al. (NEJM, 2019) sought to determine whether supplementation with n-3 long-chain polyunsaturated fatty acids from early pregnancy through 34 weeks gestation reduced the incidence of preterm birth

Multicenter, double-blind, randomized trial (RCT)
Participants
- Single or multiple fetuses
- No fetal anomalies
- Exclusion: Taking daily supplements containing >150 mg of n−3 long-chain polyunsaturated fatty acids
Groups
- n-3 group (3 capsules): 900 mg of n−3 long-chain polyunsaturated fatty acids daily (approximately 800 mg of DHA and approximately 100 mg of eicosapentaenoic acid)
- Control group (3 capsules): Vegetable-oil capsules that contained trace n−3 long-chain polyunsaturated fatty acids daily
Intervention time period: <20 weeks until 34 weeks
Primary outcome
- Early preterm delivery (< 34 weeks)
Secondary outcomes
- Additional pregnancy, delivery, and neonatal outcomes

5,486 pregnancies
- 2,734 in the n−3 group | 2,752 in the control group
Mean duration of gestation: 273 days in both groups
There was no significant difference in primary outcome (early preterm delivery)
- n-3 group: 2.2%
- Control group: 2.0%
- Adjusted relative risk (RR) 1.13 (95% CI, 0.79 to 1.63; P=0.50)
There were no significant differences in secondary outcomes
- Overall preterm delivery
- Post-term induction of labor or cesarean section
- Birth weight NICU admission
There were more LGA infants in the n−3 group
- adjusted RR 1.30 (95% CI, 1.02 to 1.65)
Minor GI upset was reported more frequently in the n-3 group

N-3 long-chain polyunsaturated fatty acids did not reduce early preterm delivery in a general population of pregnant women

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