Supplementary Material for: Unveiling the Hidden Burden: An Umbrella Review of Congenital Anomalies among Newborns in Low and Middle-Income Countries

Background: Congenital anomalies (CAs) are a major cause of newborn mortality and long-term disabilities, especially in developing countries. Research on CAs is limited and inconclusive. This umbrella review evaluates the pooled prevalence, patterns, and determinants of CAs among newborns in low- and middle-income countries. Methods: We conducted a comprehensive search across databases, including PubMed and Cochrane Library, until 31 December 2024. Study quality was assessed using the AMSTAR checklist. Heterogeneity was measured with the I² test and Cochrane Q test, while publication bias was evaluated through funnel plots, Egger's, and Begg's tests. The pooled prevalence of CAs and determinants was calculated using the DerSimonian and Laird random-effects model. Results: Seven studies revealed a pooled prevalence of CAs at 15 per 1,000 births (95% CI: 9.00, 21.00), with the highest rate in low-income countries at 18 per 1,000 (95% CI: 8.00, 27.00). Musculoskeletal and urogenital anomalies were the most prevalent, at 8 and 4 per 1,000 births, respectively. Key predictors include lack of folic acid supplementation (AOR 4.18, 95% CI: 2.35, 6.02), khat chewing (AOR 3.5, 95% CI: 2.97, 4.03), maternal illness (AOR 3.55, 95% CI: 3.37, 4.73), and drug use during pregnancy (AOR 4.37, 95% CI: 1.21, 7.54). Conclusion: The pooled prevalence of CAs is significantly higher than WHO reports, with musculoskeletal and urogenital defects being the most common. Key risk factors include maternal illness, unidentified drug use, khat chewing, and lack of folic acid supplementation. Enhancing folic acid intake and targeting these risk factors are essential for policymakers. Keywords: Associated factors, congenital anomalies, low and middle-income countries, prevalence, umbrella review