Background: Previous spontaneous preterm birth (sPTB) is an important risk factor for recurrent PTB, yet consensus on the lower limit of PTB is lacking. This complicates the identification of patients at risk for recurrent PTB. Objectives: To assess the risk of recurrent preterm birth following spontaneous extreme PTB between 16 ⁺⁰ - 27 ⁺⁶ weeks and the association with the interpregnancy interval. Design: A nationwide retrospective cohort study. Setting: Data from the Perinatal Registry of the Netherlands. Population: Nulliparous women with a singleton pregnancy that ended in sPTB between 16 ⁺⁰ and 27 ⁺⁶ weeks of gestation without congenital anomalies or antenatal death between 2010-2014 and had a subsequent pregnancy in the 5 years following. Main outcome measures: Recurrent preterm birth < 37 weeks. Results: 1011 women with linked pregnancies were included. The risk of PTB < 37 weeks with prior spontaneous birth between 16 ⁺⁰-19 ⁺⁶, 20 ⁺⁰-23 ⁺⁶, and 24 ⁺⁰-27 ⁺⁶ weeks was respectively 19.0%, 29.5% and 27.6%. The risk of subsequent PTB < 24 weeks was 5.7%, 7.2% and 4.3%. A short interpregnancy interval of 0-3 months was associated with increased odds for recurrent PTB < 32 weeks (OR 2.3 95% CI 1.4-3.7) and PTB < 37 weeks (OR 1.8 95% CI 1.2-2.6). Conclusion: Patients with previous sPTB from 16 weeks GA onwards are at high risk for recurrent PTB and should be regarded as such in the consideration of preventive measures to prevent recurrent adverse pregnancy outcomes.