Twinning and major birth defects, National Birth Defects Prevention Study, 1997–2007
April L Dawson, Sarah C Tinker, Denise J Jamieson, Charlotte A Hobbs, R J Berry, Sonja A Rasmussen, Marlene Anderka, Kim M Keppler-Noreuil, Angela E Lin, Jennita Reefhuis, the National Birth Defects Prevention Study
J Epidemiol Community Health Nov 2016, 70 (11) 1114-1121; DOI: 10.1136/jech-2015-206302