Background: Maternal obesity is a growing health burden associated with adverse cardiometabolic health outcomes in the offspring. Higher omega-3 polyunsaturated fatty acids (n3 PUFA) status in pregnancy is associated with higher birthweight. However, the effect of n3 supplementation, specifically in pregnant women with overweight and obesity, on fetal growth and adiposity has not been explored.

Objective: To examine the effect of n-3 supplementation in overweight and obese pregnancy on offspring anthropometry and body composition.

Methods: A secondary analysis of a double-blind randomized controlled trial of pregnant women with pre-pregnancy BMI≥ 25 randomized to daily DHA plus EPA (2 g/d) or placebo (wheat germ oil) from 10-16 weeks gestation to delivery. We compared the following newborn outcomes i) birthweight z-score derived from anthropometrics, ii) % adiposity, fat-mass and fat-free mass using PeaPodTM and skin fold thickness measurement, by randomization group using Student T-test and Wilcoxon rank-sum for bivariate analyses, and linear regression adjusting for gestational age (GA) and sex.

Results: For the 46 mother-child dyads with complete exposure and outcome data, median (IQR) maternal BMI was 30.2 (27.9, 35.5) kg/m2. Gestation was longer in the treatment vs. placebo group (40 (38.6,40.1) vs. 38.9 (38.0,39.4) weeks, p=0.009). Sex- and GA- specific birthweight z-score (-0.2 ± 0.7 vs. -0.6 ± 0.6-unit, p =0.035), but not birth length z-score (-0.3 ± 0.7 vs. -0.6 ± 0.6-unit, p =0.21), was higher in the treatment vs. placebo group. N-3 treatment was associated with higher fat-free mass (β 131.4g higher for treatment vs. control, 95% CI 3.1, 259.7) by skinfolds but not %bodyfat or fat mass at birth.

Conclusion: n-3 supplementation early in pregnancy in women with obesity increased birthweight, but this results from increased fetal lean mass accrual. Future investigations should explore the long-term impact of this intervention on offspring cardiometabolic health.


C. Monthe-Dreze: None. S. Enstad: None. S. Sen: None. S. Hauguel de Mouzon: None. P. Catalano: None.


National Institutes of Health (RHD057236); Case Western Reserve University/Cleveland Clinic Clinical and Translational Science Award (UL1RR024989)

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