Global, regional, and national levels and trends in maternal mortality between 1990 and 2015, with scenario-based projections to 2030: a systematic analysis by the UN Maternal Mortality Estimation Inter-Agency Group - Alkema, L; Chou, D; Hogan, D (Lancet, 2016)
. Doi: 10.1016/S0140-6736(15)00838-7