Maternal supplementation with docosahexaenoic acid during pregnancy does not affect early visual development in the infant: a randomized controlled trial.

Multicenter, double-blind randomized controlled trial in healthy singleton pregnancies in Australia, with enrollment at 18-21 weeks' gestation and no fetal abnormalities. The active arm was compared with a vegetable-oil control, and infant visual outcomes were assessed at 4 months of age.

Pregnant participants received DHA-rich fish oil capsules (Incromega 500TG) from 18-21 weeks' gestation until delivery: three 0.5-g capsules daily, providing 800 mg DHA/day and 100 mg EPA/day. The control group received matched capsules containing blended vegetable oil.

Maternal DHA supplementation during the second half of pregnancy did not improve early infant visual development. Primary VEP acuity at 4 months was 8.37 ± 2.11 cycles per degree in the DHA group (n = 89) versus 8.55 ± 1.86 cycles per degree in controls (n = 93; P = 0.55), and no difference was reported for VEP latency. Exploratory analyses also showed no benefit among infants fed only breast milk (8.8 ± 2.0 vs 8.7 ± 2.4 cycles per degree; P = 0.9), after adjustment for postnatal DHA exposure (8.6 ± 2.1 vs 8.7 ± 2.1 cycles per degree; P = 0.63), or among infants fed formula without DHA (7.7 ± 1.6 vs 8.1 ± 1.6 cycles per degree; P = 0.39). Although maternal DHA increased cord blood and breast-milk DHA/EPA, the biochemical changes did not translate into improved visual acuity, and maternal smoking was independently associated with poorer infant visual acuity.

Follow-up was short, limited to infant testing at 4 months, so longer-term visual effects were not assessed. The trial enrolled healthy term singleton pregnancies, which limits generalizability, and several subgroup analyses were exploratory and likely underpowered. The extraction does not provide detailed VEP latency results, and some sample counts differ across analyses because of incomplete outcome data.