Dominique Heinke, Janet W Rich-Edwards, Paige L Williams, Sonia Hernandez-Diaz, Marlene Anderka, Sarah C Fisher, Tania A Desrosiers, Gary M Shaw, Paul A Romitti, Mark A Canfield, Mahsa M Yazdy
BACKGROUND: Risk factors for birth defects are frequently investigated using data limited to liveborn infants. By conditioning on survival, results of such studies may be distorted by selection bias, also described as "livebirth bias." However, the implications of livebirth bias on risk estimation remain poorly understood. OBJECTIVES: We sought to quantify livebirth bias and to investigate the conditions under which it arose. METHODS: We used data on 3994 birth defects cases and 11 829 controls enrolled in the National Birth Defects Prevention Study to compare odds ratio (OR) estimates of the relationship between three established risk factors (antiepileptic drug use, smoking, and multifetal pregnancy) and four birth defects (anencephaly, spina bifida, omphalocele, and cleft palate) when restricted to livebirths as compared to among livebirths, stillbirths, and elective terminations...
November 2020: Paediatric and Perinatal Epidemiology