BackgroundInsomnia is the most common sleep disorder in the general population, especially among pregnant women, and it is considered a major public health issue. Not only can it cause mental and physical problems in pregnant women, but it may also affect the growth of the fetus. However, there are few reports on the prevalence and influencing factors of insomnia symptoms in third-trimester women in China. The objective of this study was to assess the prevalence of insomnia symptoms among pregnant women in the third trimester in a moderately developing region of China and to further explore the associated factors of insomnia symptoms from various aspects.MethodsA cross-sectional survey was conducted among eligible pregnant women in the third trimester from December 2022 to February 2023. Data on socio-demographic characteristics, clinical characteristics, and behavioral and psychological characteristics of pregnant women were collected through a structured questionnaire. The Chi-square test and multivariate logistics regression were applied to explore the associated factors of insomnia symptoms.ResultsA total of 535 pregnant women in the third trimester were included in this study, and the prevalence of insomnia symptoms was 59.8%. Multivariate logistic regression analysis revealed that pregnant women who lived together with elders (OR: 0.58, 95%CI: 0.40–0.86), had low perceived stress (OR: 0.58, 95%CI: 0.35–0.97), had no threatened abortion (OR: 0.55, 95%CI: 0.32–0.93) and had good doctor-patient communication (OR: 0.66, 95%CI: 0.45–0.98) were more likely to stay away from insomnia symptoms. However, pregnant women with anxiety symptoms (OR: 2.27, 95%CI: 1.28–4.03), fear of childbirth (OR: 1.63, 95%CI: 1.11–2.40) and a high experience of COVID-19 fear (OR: 1.61, 95%CI: 1.03–2.54) tended to have insomnia symptoms.ConclusionsThe prevalence of insomnia symptoms in pregnant women is high in Lianyungang city in eastern China in the third trimester. Insomnia symptoms is influenced by multiple factors. There is an urgent need to develop interventions to reduce the prevalence of insomnia symptoms in the third trimester and to focus on pregnant women with risk factors for insomnia symptoms.