Background. Exposure to suboptimal intrauterine environment might induce structural and functional changes that can affect neonatal health. Telomere length as an important indicator of cellular health has been associated with increased risk for disease development. Objectives. This study was aimed to examine the independent and combined effects of maternal, obstetric, and foetal factors on cord blood telomere length (TL). Methods. Pregnant women at the gestational age of 20th to 24th week who attended the antenatal clinic of a major local hospital in Hong Kong were recruited. Participants were asked to complete a questionnaire on demographics, health-related quality of life, and history of risk behaviors. Medical history including pregnancy complications and neonatal outcomes was obtained from electronic medical records of both mother and neonate. Umbilical cord blood was collected at delivery for TL determination. Results. A total of 753 pregnant women (average age: 32.18 ± 4.51 years) were recruited. The prevalence of maternal infection, anaemia, and hypertension during pregnancy was 30.8%, 30.0%, and 6.0%, respectively. The adjusted regression model displayed that maternal infection was negatively associated with cord blood TL ( β = − 0.18 , p = 0.026 ). This association became even stronger in the presence of antenatal anaemia, hypertension, delivery complications, or neonatal jaundice ( β = − 0.25 to −0.45). Conclusions. This study consolidates evidence on the impact of adverse intrauterine environment at the cellular level. Maternal infection was significantly associated with shorter cord blood TL in a unique manner such that its presence may critically determine the susceptibility of telomere to other factors.