Background: Prenatal care has proven to play an invaluable role in the reduction of maternal and perinatal mortality. The care provided to the parturient includes risk assessment, health promotion and education, and therapeutic intervention if need arises. The cardinal point of antenatal care is mainly but not limited to ensuring the delivery of a healthy newborn with minimal or no risk to the mother. The importance of prenatal care cannot be overemphasized especially in developing countries with high fertility rate, increased tendency to large family size and increased maternal mortality. Objectives: To determine the sociodemographic characteristics of booked and unbooked pregnant women and to ascertain any differences in maternal and perinatal outcome. Materials and Method: A retrospective cohort study at 68 Nigerian Army reference hospital from January 2020 to December 2023. All the antennal records of women booked in our facility within the period of study were retrieved. Maternity records that included all unbooked deliveries were all retrieved. The variables of interest were maternal age, parity, educational status, antenatal care (ANC) attendance, mode of delivery, obstetrics complications and pregnancy outcomes. Data was analysed using SPSS version 29. P<0.05 was considered significant. Results: A total number of 5032 patients were seen during the four-year period of review. Booked cases were 3572 (70.99%) while unbooked was 1460 (29.01%). Fetomaternal adverse outcome and complication were more in the unbooked category with high operative delivery 87.05% in the unbooked patients. Conclusion: The study showed that more adverse pregnancy outcomes occurs when women are unbooked during pregnancy. Continued utilisation of quality antenatal and delivery care services in our environment will significantly improve pregnancy outcome while reducing maternal and perinatal mortality and morbidity.