Can fish oil use during pregnancy improve infant outcomes?

Supplementation with fish oil during pregnancy of mothers with overweight or obesity does not appear to have a significant impact on the body composition of infants, reveals a recent study.

In this double-blind, randomized controlled trial, mothers with overweight or obesity received either 6-g fish oil (3.55 g/d of ­n-3 polyunsaturated fatty acids) or olive oil (control) from mid-pregnancy until 3 months postpartum. Eligible women (body mass index [BMI] ≥25 kg/m²) had singleton pregnancies at 12 to 20 weeks of gestation.

Infant body fat percentage (DXA scans) at 2 weeks of age was the primary outcome, while maternal metabolic markers during pregnancy, infant anthropometry at 2 weeks and 3 months of age, and metabolic markers at 3 months were secondary.

Overall, 129 mothers were included, and 98 infants had a DXA scan at 2 weeks. Imputed and nonimputed analyses revealed that fish oil supplementation had no substantial effects on infant body fat percentage and on secondary outcomes at 2 weeks. However, infants of mothers in the fish oil group had a higher BMI z-score (p=0.025) and ponderal index (p=0.017) at age 3 months.

On the other hand, fish oil supplementation resulted in 17-percent lower maternal triglycerides at 30 weeks of pregnancy (p=0.0002) and 21-percent lower infant triglycerides at 3 months of age (p=0.016), with no significant impact on maternal or infant insulin resistance.

Furthermore, the rate of emergency caesarean section was lower in the fish oil group (adjusted risk ratio, 0.38, 95 percent confidence interval, 0.16‒0.90; p=0.027).

“There is a need to follow up the offspring to determine whether the observed metabolic effects persist,” the authors said.