Introduction: The objective of the study was to estimate the prognostic factors associated with premature delivery and other clinical outcomes in pregnant women undergoing appendectomy in Colombia. Methods: A retrospective cohort study was conducted from the administrative healthcare records, which included pregnant women affiliated with the contributory health system in Colombia and undergoing appendectomy, between January 2013 and November 2016. The birth rate was estimated, premature delivery rate, the 30-day mortality rate, 30-day maternal admission to Intensive Care Unit (30-ICU), 30-day readmission (30-R-Adm), and low birth weight (LBW). Multivariate logistic regressions were used to identify these three prognostic factors. Results: 1589 women were included in the study. Mean age was 26.43 ± 5.79, 17.94% of the appendectomies were performed in the third trimester, 6.10% were laparoscopic appendectomies and 22% required peritonitis drainage. The Rates of premature delivery, 30-day mortality, 30-ICU, 30-R-Adm and LBW were 12%, 0.13%, 9.75%, 16.93% and 3.34%, respectively. Age under 18 years, appendectomy in the third trimester and peritonitis drainage were associated with an increased risk of premature delivery. Obstetric comorbidities index, appendectomy in the third trimester and peritonitis drainage were associated with an increased maternal admission to ICU. Conclusions: Appendectomy in the third trimester and complicated appendicitis are prognostic factors associated with premature delivery in Colombian pregnant women undergoing to appendectomy.