Spatiotemporal patterns and surveillance artifacts in maternal mortality in the United States: a population-based studyResearch in context oleh K.S. Joseph, Sarka Lisonkova, Amélie Boutin, Giulia M. Muraca, Neda Razaz, Sid John, Yasser Sabr, Sophie Simon, Johanna Kögl, Elizabeth A. Suarez, Wee-Shian Chan, Azar Mehrabadi, Justin S. Brandt, Enrique F. Schisterman, Cande V. Ananth