Marinovich ML, Regan AK, Gissler M, et al. - Researchers conducted this cohort study to examine the impact of interpregnancy interval (IPI) on preterm birth (PTB) according to whether the previous birth was preterm or term. Participants in the study were 3,213,855 women who gave birth to first and second singleton livebirths. The association between IPI and PTB is influenced by whether the previous pregnancy was preterm or not. The odds ratios for short and long IPIs were higher among women who had a previous term birth than a previous PTB, which supports the maternal depletion hypothesis for short IPI. Given the high risk of recurrence and assuming a causal relationship between IPI and PTB, IPI remains a potentially modifiable risk factor for women with previous PTB.