Association between triglyceride glucose index and spontaneous preterm birth: Evidence from a retrospective cohort study

Objective The triglyceride glucose (TyG) index has been recommended as an effective auxiliary biomarker for insulin resistance (IR). However, the dose‐effect relationship between maternal TyG index during the three trimesters of pregnancy and subsequent spontaneous preterm birth (sPTB) remains to be elucidated. The aim of the present study was to evaluate the association between maternal trimester‐specific TyG index and sPTB risk. Methods Pregnant individuals who received routine prenatal care and delivered at Peking University International Hospital between January 2020 and June 2024 were recruited for this retrospective cohort study. Maternal lipid and glucose profiles were collected, and TyG levels were calculated. Logistic regression models and generalized additive models (GAM) were employed to detect the potential relationships between maternal TyG index and sPTB risk. Results An excessively high maternal TyG index was correlated with an elevated risk of sPTB across all three trimesters, but the specific dose‐effect relationships varied. In the first trimester, a semi‐linear association was detected; the elevated TyG index was positively correlated with sPTB risk when exceeding the potential inflection point of 8.34. In the third trimester, a moderate TyG index around the identified inflection point (9.21) was associated with a lower risk of sPTB. In the second trimester, the maternal TyG index was positively correlated with subsequent sPTB occurrence. Conclusion Maternal TyG index during pregnancy is associated with the sPTB risk, but its dose‐effect varied across different trimesters. These findings may help to inform future research on trimester‐specific metabolic profiles.