IntroductionHIV can greatly impact the quality of life of pregnant women and may cause adverse pregnancy outcomes, such as preterm birth (PB) and mother-to-child transmission (MTCT). The purpose of this study was to analyse the influencing factors of PB and MTCT in HIV-positive pregnant women.MethodsHIV-positive pregnant women in Henan Province between January 2016 and December 2022 were selected for the study. Data were collected through the Management Information System for the Prevention of MTCT of HIV, syphilis and hepatitis B. Information on their demographic and clinical characteristics, treatment status and pregnancy outcomes was collected. A logistic regression model and χ2automatic interaction detector (CHAID) decision tree model were used to analyse the correlation factors of PB and MTCT.ResultsThe average age of the 1073 study participants was 28.44 years, with an incidence of 11.93% for PB and 6.71% for MTCT. Hepatitis B virus or hepatitis C virus coinfection (OR=3.686, 95% CI 1.630 to 8.333) and Han nationality (OR=0.426, 95% CI 0.194 to 0.936) were risk factors for PB. Unknown HIV infection prior to pregnancy (OR=2.006, 95% CI 1.233 to 3.264) and primipara (OR=5.125, 95% CI 1.202 to 21.849) were risk factors for MTCT. The CHAID decision tree model was used to screen for the six and two influencing factors of PB and MTCT in HIV-positive women, respectively.ConclusionEarly HIV testing, scientific counselling, precise maternal HIV infection assessment and targeted prevention measures can help prevent PB and MTCT in HIV-positive pregnant women.