Effect of reducing the n-6:n-3 long-chain PUFA ratio during pregnancy and lactation on infant adipose tissue growth within the first year of life: an open-label randomized controlled trial.

Open-label, randomized controlled trial conducted in healthy pregnant women in early gestation at a single center in Munich, Germany. Participants had prepregnancy BMI between 18 and 30 kg/m2 and were randomized 1:1 to the active maternal n-3 PUFA plus arachidonic acid reduction strategy or to healthy-diet counseling alone.

Pregnant participants in the active arm received oral fish-oil capsules providing 1200 mg/day n-3 long-chain PUFA from the 15th week of gestation to 4 months postpartum, including 1020 mg DHA and 180 mg EPA plus 9 mg vitamin E daily. The regimen was paired with dietary counseling to reduce arachidonic acid intake to about 90 mg/day and to limit meat intake, while the control group received brief healthy-diet counseling and was asked to avoid fish-oil or DHA supplements.

The intervention did not measurably reduce infant adipose tissue growth or fat mass during the first year of life. At 4 months postpartum, the sum of 4 skinfolds was 25.3 +/- 4.1 mm in the intervention group versus 25.2 +/- 4.3 mm in controls, with a mean difference of 0.1 (95% CI -1.2, 1.2); at 1 year, values were 24.1 +/- 4.4 mm versus 24.1 +/- 4.1 mm, with a mean difference of 20.0 mm (95% CI 21.3, 1.3 mm). Ultrasonography also showed no significant between-group differences at 6 weeks, 4 months, or 12 months, and no side effects of the intervention were observed. Any early differences in birth size were attributed to longer gestation and were not evident by 1 year, supporting the authors' conclusion that long-term follow-up is needed.

Open-label design and a single-center, relatively homogeneous cohort of healthy, well-educated white women limit generalizability. Follow-up attrition reduced the number with outcome data at later time points, and the intervention effect may have been too small or too brief to detect changes within the first year of life. Longer-term outcomes beyond 1 year were not assessed.