Recurrent pregnancy loss: systematic review and meta-analysis of overall prevalence and the distribution of major etiological categories.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 41994445 · doi:10.3389/fmed.2026.1805994
What was done
Systematic review and meta-analysis of observational studies identified across PubMed/Medline, EMBASE, Cochrane Library, Scopus, and Web of Science (PROSPERO: CRD42024517675). The authors performed random-effects meta-analyses using inverse-variance weighting, restricted maximum likelihood estimation, and Freeman-Tukey transformations to estimate population prevalence and pooled proportions of major recurrent pregnancy loss (RPL) etiological categories. Heterogeneity was assessed using I2 and tau2, alongside subgroup and meta-regression analyses.
What was found
Across 105 included studies comprising 47,907 women with RPL: - Population-based prevalence of RPL was reported in only 2 studies, yielding an estimate of approximately 1% (95% CI, 1-1%). - Idiopathic/unexplained RPL was the most common category at 37% (95% CI, 30-44%; I2 = 94.3%). - Acquired thrombophilia accounted for 12% (95% CI, 9-15%). - Endocrine factors accounted for 8% (95% CI, 6-10%). - Anatomical factors accounted for 6% (95% CI, 5-8%). - Hereditary thrombophilia accounted for 6% (95% CI, 5-8%).
Why it matters
This review quantifies the major etiological categories of recurrent pregnancy loss across a large pooled cohort, highlighting that more than one-third of cases remain unexplained and demonstrating substantial between-study variability.
Limits
Population-level prevalence is derived from only 2 studies. Significant between-study heterogeneity was present across etiological categories (I2 = 94.3% for unexplained RPL), likely driven by variable diagnostic workups, definitions, and regional differences across the included observational studies.
Cited by
- contradicts In approximately 80% of recurrent pregnancy loss cases, all diagnostic test results are normal, while roughly 20% show an identifiable cause.