ObjectivesTo explore the association between liver dysfunction and premature birth (PTB).MethodsA prospective cohort of HBV-infected or uninfected pregnant women of Han nationality attending antenatal care at Nantong Maternal and Child Health Hospital was recruited from January 1st, 2012 to June 30th, 2016. Liver function tests (LFTs) were monitored through pregnancy. Robust Poisson regression was used to estimate adjusted risk ratios (RRs) on HBV infection and LFT abnormalities.ResultsAmong 35 452 pregnant women (1 073 HBV carriers and 34 379 non-HBV women), 4 266 (12.03%) had at least one instance of abnormal LFT results. One fold upper limit of normal aspartate aminotransferase (AST), two folds upper limit of normal total bilirubin, and four folds upper limit of normal total bile acid rather than HBsAg positivity, were identified as independent risk factors for PTB by Robust Possion regression analysis.ConclusionsAbnormal LFTs among pregnant women is an independent risk factor of PTB. We suggest monitoring the LFTs results of high-risk population throughout pregnancy.