Impact of country income status on the relationship between interpregnancy interval and maternal complications of pregnancy: a systematic review and meta-analysis protocol.

Authors

Hui Lin Lee, Yaduza Sivarasa, Richard W Wang, Aditya Ranganath, Ben D A Gorman, Carol A Wang, Katherine A Birchenall, Craig E Pennell

Published in

BMJ open. Volume 16. Issue 9. Pages e116774. Sep 29, 2026. Epub Sep 29, 2026.

Abstract

Both short and long interpregnancy intervals (IPIs) have been associated with adverse maternal outcomes, including uterine rupture, gestational diabetes mellitus (GDM), gestational hypertension and postpartum haemorrhage (PPH). However, the strength and consistency of these relationships remain uncertain, and there is limited information on how these associations differ according to country income status. This review is designed to examine the impact of the income status of a country on the relationship between IPI and maternal complications of pregnancy.
CINAHL, MEDLINE, EMBASE via Ovid, Global Health, LILACS and African Index Medicus will be searched using combinations of MeSH and Emtree terms with keywords. Studies included are expected to be observational studies; existing systematic reviews with no new data will be excluded. The study population will consist of women with two or more singleton births and the exposure assessed will be short IPI (<24 months, <18 months and <12 months between the birth of a child and conception of the next pregnancy) and long IPI (>60 months). The comparator group will be an IPI of 24-60 months, as recommended by several international organisations. The co-primary outcomes are preterm pre-labour rupture of membranes, PPH, pre-eclampsia, gestational hypertension, GDM, uterine rupture and maternal mortality. The income status will be categorised according to the World Bank income-based classifications for low-, middle and high-income countries. Two reviewers will independently perform study screening, data extraction and risk of bias assessment using the Newcastle-Ottawa Score. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework will be used to assess the certainty of evidence. A random effects model will be used to calculate pooled ORs with 95% CIs.
Ethics approval is not applicable for this study as no original data will be collected. The results will be disseminated through peer-reviewed publication and conference presentations.
CRD420251075283.Available from: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251075283.

PMID:
42810798
Bibliographic data and abstract were imported from PubMed on 30 Sep 2026.

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