Taken together, these results suggest that changes in lipid metabolism reflected by increases in fatty acid, ketone, and sphingomyelin content in second trimester GDM AF demonstrate changes within fetus and/or placenta metabolism that may result in alterations in lipid processing, the innate immune response, and insulin sensitivity of the feto–maternal unit as early as the second trimester of pregnancy. The gene discussed is INS; the disease is gestational diabetes.