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.