Epidemiology of limb reduction defects as registered in the Medical Birth Registry of Norway, 1970-2016: Population based study

Background Following the Thalidomide disaster, the Medical Birth Registry of Norway (MBRN) was established in 1967, with epidemiological surveillance of congenital anomalies as one main aim. Limb reduction defects (LRD) constitute a rare and heterogeneous anomaly group, where correct registration and classification is important for surveillance and research. We aimed at reviewing and recoding LRD cases in the MBRN using the same classification system for all years, and evaluate time trends, characteristics and risk factors, 1970–2016.