Interpregnancy interval and risk of perinatal death: a systematic review and meta‐analysis

Background Interpregnancy interval (IPI) <6 months is a potentially modifiable risk factor for adverse perinatal health outcomes. Objective This systematic review evaluated the international literature on the risk of perinatal death associated with IPI. Search strategy Two independent reviewers screened titles and abstracts identified in MEDLINE, EMBASE and Scopus from inception to 4 April 2019 (Prospero Registration #CRD42018092792). Selection criteria Studies were included if they provided a description of IPI measurement and perinatal death, including stillbirth and neonatal death. Data collection and analysis A narrative review was performed for all included studies. Random effects meta‐analysis was used to compare unadjusted odds of perinatal death associated with IPI <6 months and IPI ≥6 months. Analyses were performed by outcome of the preceding pregnancy and study location. Main results Of the 624 unique articles identified, 26 met the inclusion criteria. The pooled unadjusted odds ratio of perinatal death for IPI <6 months was 1.34 (95% CI 1.17–1.53) following a previous live birth, 0.85 (95% CI 0.73–0.99) following a previous miscarriage and 1.07 (95% CI 0.84–1.36) following a previous stillbirth compared with IPI ≥6 months. However, few high‐income country studies reported an association after adjustment. Fewer studies evaluated the impact of long IPI on perinatal death and what evidence was available showed mixed results. Conclusions Results suggest a possible association between short IPI and risk of perinatal death following a live birth, particularly in low‐ to middle‐income countries. Tweetable abstract Short IPI <6 months after a live birth was associated with greater risk of perinatal death than IPI ≥6 months.