Incidence of postpartum haemorrhage defined by quantitative blood loss measurement: a national cohort oleh Sarah F. Bell, Adam Watkins, Miriam John, Elinore Macgillivray, Thomas L. Kitchen, Donna James, Cerys Scarr, Christopher M. Bailey, Kevin P. Kelly, Kathryn James, Jenna L. Stevens, Tracey Edey, Rachel E. Collis, Peter W. Collins