Sources of bias in studies reporting birth prevalence of congenital anomalies: a scoping review and reporting checklist.

This article focuses on identifying sources of bias in studies reporting the birth prevalence of congenital anomalies in countries of the World Health Organization South-East Asia Region (WHO-SEAR). Through a scoping review of 47 studies, mostly hospital-based and single-center, the authors found wide variation in reported prevalence (0.21% to 9.68%) and multiple biases including sampling bias from non-random, referral hospital samples; information bias due to inconsistent use of classification systems like ICD-10 and unclear reporting of cases; observer bias related to variable qualifications and training of examiners; and reporting bias from inconsistent terminology and unclear denominators. To address these issues, the authors developed a checklist (CD-Checklist) aimed at guiding researchers in low- and middle-income country (LMIC) settings to minimize bias in future prevalence studies. The review highlights the challenges in generating robust, generalizable data on congenital anomalies in LMIC health systems and underscores the need for standardized study design and reporting practices.