BACKGROUND: Excess maternal triglyceride (mTG) exposure during early or late pregnancy increases risks of adverse pregnancy outcomes. However, it is inconclusive whether persistently high maternal triglyceride during whole pregnancy has more negative associations. OBJECTIVE: To explore whether persistently high maternal triglyceride (mTG) levels from early to late pregnancy further increases the risk of adverse pregnancy outcomes. METHODS: We included 12,715 women who had a singleton birth and who underwent routine serum lipid screenings in both early (9-13 weeks) and late (28-42 weeks) pregnancy during May 2018 to July 2019 in a university-based maternity center. Risks for gestational diabetes mellitus (GDM), preeclampsia, preterm delivery, small/large for gestational age (LGA) were estimated. RESULTS: Elevated mTG levels during early pregnancy were associated with increased risks of preterm delivery (AOR, 1.52; 95% CI, 1.21 to 1.90), preeclampsia (1.75; 1.29 to 2.36), gestational diabetes mellitus (1.95; 1.69 to 2.25), and LGA (1.28; 1.12 to 1.46). Compared with those with low mTG levels both in the 1st and 3rd trimesters, persistently high mTG levels increased the risks of preeclampsia (2.53; 1.66 to 3.84), GDM (1.97; 1.57 to 2.47), and LGA (1.68; 1.37 to 2.07). However, persistently high mTG levels only slightly increased risk of LGA when compared with high mTG levels during the 1st trimester alone (1.34, 1.01 to 1.77).