Abstract: Objective：To investigate the effect of free fatty acid (FFA) on the incidence of preeclampsia and/or gestational diabetes mellitus (GDM) during late pregnancy. Methods：A total of 417 pregnant women with preeclampsia and/or GDM were selected as the observation group, and another 2 018 normal pregnant women as the control group. The levels of serum lipids including total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), and free fatty acid (FFA) were measured and compared between the two groups. The association between lipid metabolism and pregnancy complications were analyzed by logistic regression models. Results：After adjusting for confounding factors, including pre-pregnancy body mass index (BMI), maternal age and gestational age at blood sampling, FFA concentrations measured during late pregnancy were associated with a significantly increased risk of preeclampsia, GDM and composite of preeclampsia and GDM(P<0.01). Furthermore, elevated maternal TG levels increased the risk of preeclampsia (P<0.001). Conclusions：FFA levels during late pregnancy show strong relationships with the incidence of preeclampsia or GDM.