Management and implications of severe COVID-19 in pregnancy in the UK: data from the UK Obstetric Surveillance System national cohort - Vousden, N; Ramakrishnan, R; Bunch, K; Morris, E; Simpson, N; Gale, C; O'Brien, P; Quigley, M; Brocklehurst, P; Kurinczuk, JJ; Knight, M (Acta Obstetricia et Gynecologica Scandinavica, 2022)