In the United Kingdom, the United Kingdom Obstetric Surveillance System (UKOSS), working with the Department of Health and Health Protection Agency, collected information on pregnancies reported to be affected by A H1N1 from 221 of the 223 (99%) obstetric units in the UK during the pandemic. UKOSS assessed the data on morbidity in pregnancy. The Centre for Maternal and Child Morbidity UKOSS was able to obtain complete data on 241 women admitted to hospital with confirmed A H1N1. During that period, there were 314,135 maternities, representing an incidence of 7.7 hospitalised cases per 10,000 maternities. Twenty percent (1.6 per 10,000 maternities) of these women were admitted to the Intensive Care Unit.