Placental mobilization of free fatty acids contributes to altered materno-fetal transfer in obesity.

BACKGROUND: Metabolic changes in obese pregnant women, such as changes of plasma lipids beyond physiological levels, may subsequently affect fetal development in utero. These metabolic derangements may remain in the offspring and continue throughout life. The placenta mediates bidirectional exchange of nutrients between mother and fetus. The impact of prepregnancy obesity on placental transfer of lipids is still unknown. OBJECTIVE: We aimed to examine materno-to-fetal free fatty acid (FFA) transfer by a combined experimental and modeling approach. Flux of (13)C-labeled FFA was evaluated by ex vivo perfusion of human placentae as a function of prepregnancy obesity. Mathematical modeling complemented ex vivo results by providing FFA kinetic parameters. RESULTS: Obesity was strongly associated with elevated materno-to-fetal transfer of applied (13)C-FFA. Clearance of polyunsaturated (13)C-docosahexaenoic acid (DHA) was most prominently affected. The use of the mathematical model revealed a lower tissue storage capacity for DHA in obese compared with lean placentae. CONCLUSION: Besides direct materno-to-fetal FFA transfer, placental mobilization accounts for the fetal FA supply. Together, with metabolic changes in the mother and an elevated materno-fetal FFA transfer shown in obesity, these changes suggest that they may be transmitted to the fetus, with yet unknown consequences.