Effect of n-3 long-chain polyunsaturated fatty acid supplementation of women with low-risk pregnancies on pregnancy outcomes and growth measures at birth: a meta-analysis of randomized controlled trials.

Systematic review and meta-analysis of 6 randomized controlled trials in healthy pregnant women with low-risk pregnancies. The pooled analysis included 1278 infants and compared n-3 LC-PUFA supplementation with placebo, no supplementation, or control oils/foods.

Across 6 randomized trials, pregnant women received n-3 long-chain polyunsaturated fatty acid supplementation in varied forms, including cod liver oil, fish oil, high-DHA eggs, and DHA/EPA-containing preparations, for the pregnancy intervention period until birth. Doses and formulations differed by trial, with comparisons against placebo, no supplementation, or usual/alternative oil or egg controls.

n-3 LC-PUFA supplementation during pregnancy produced a small benefit overall, most clearly by modestly prolonging gestation and slightly increasing head circumference at birth. Pooled duration of pregnancy increased by 1.57 days (95% CI 0.35, 2.78), while birth weight was not significantly changed (WMD 54 g; 95% CI -3.1, 111 g) and birth length was also not significantly changed (WMD 0.23 cm; 95% CI -0.04, 0.5 cm). Head circumference increased by 0.26 cm (95% CI 0.02, 0.49), but this finding was lost in sensitivity analysis (WMD 0.26 cm; 95% CI -0.02, 0.53). No significant differences were seen for preterm delivery, low birth weight, preeclampsia/eclampsia, cesarean delivery, or gestational diabetes, and safety signals were not clearly concerning overall.

The included trials were few and heterogeneous in formulation, dose, and comparator, which limits precision and generalizability. Several outcomes were null, the head circumference finding was not robust in sensitivity analysis, and adverse effects were variably reported. Long-term infant growth and developmental effects were not addressed.