Background: Studies have demonstrated associations between polyunsaturated fatty acids (PUFAs) and adiposity. It is unclear whether PUFAs in pregnancy have an effect on maternal weight retention after childbirth, which can contribute to long-term obesity.

Objective: We examined the association of maternal plasma PUFAs in pregnancy with 18-mo postpartum weight retention (PPWR) in a multiethnic Asian cohort.

Design: We studied pregnant women (n = 653) recruited between June 2009 and September 2010 from a prospective cohort. At 26-28 wk of gestation, plasma phosphatidylcholine PUFA concentrations were measured and determined as percentages of total fatty acids (FAs). PPWR was calculated based on the difference between measured weight at the first antenatal clinic visit and at 18 mo postpartum.

Results: The median retained weight of women was 0.90 kg (IQR: -1.40, 3.25) at 18 mo postpartum. Of 653 women, 544 women (83.3%) had PPWR of <5 kg and 109 (16.7%) had PPWR of ≥5 kg. In adjusted linear regression models, higher plasma eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total ω-3 (n-3) PUFA concentrations were associated with lower PPWR [EPA: β = -0.62 kg/1% increase of total FAs (95% CI: -1.18, -0.05); DHA: β = -0.24 kg/1% increase (95% CI: -0.45, -0.02); total ω-3 PUFAs: β = -0.20 kg/1% increase (95% CI: -0.36, -0.03)], whereas a higher ratio of plasma ω-6-to-ω-3 PUFAs was associated with a higher PPWR [β = 0.21 kg/unit increase (95% CI: 0.05, 0.36)].

Conclusions: Higher plasma percentages of ω-3 PUFAs and a lower ratio of ω-6-to-ω-3 PUFAs in the late-second trimester of pregnancy are associated with less weight retention at 18 mo postpartum. This may offer an alternative strategy to assist postpartum weight reduction by increasing EPA and DHA status together with a decreased ratio of ω-6-to-ω-3 PUFA through diet or fish-oil supplementation during pregnancy.