To test the earlier suggested hypothesis that intake of long-chain n-3 fatty acids from fish oil may delay the timing of spontaneous delivery and to test if alpha-linolenic acid, provided as flax oil capsules, shows the same effect.Design
Randomised controlled trial including women reporting low dietary fish intake. The women were allocated in the proportions of 1:1:1:1:1:1:2 into six treatment groups and a control group, respectively, from week 17–27 of gestation. The treatment groups received fish oil, in various doses, or flax oil, and the control group did not receive any treatment.Setting
The Danish National Birth Cohort.Sample
A total of 3098 women allocated into six treatment groups and one control group.Methods
The six intervention groups were offered fish oil capsules in doses of 0.1, 0.3, 0.7, 1.4 and 2.8 g of eicosapentaenoic acid and docosahexaenoic acid per day or 2.2 g of alpha-linolenic acid (ALA) per day from week 17–27 of gestation until delivery.Main outcome measures
Timing of spontaneous delivery.Results
No differences in timing of spontaneous delivery was detected in the fish oil groups or the flax oil group, compared with the control group. The difference in timing of spontaneous delivery in the group receiving the highest fish oil dose compared with the control group was 0.8 days (95% CI: –2.3 to 1.0). Only a minority of the women in the intervention groups took capsules until delivery.Conclusion
Possible explanations for these findings include no true effect of n-3 fatty acids on spontaneous delivery or a quick-acting effect not detectable in this trial.