The NHS Benchmarking Network were commissioned by NHS England to undertake a bespoke data collection on perinatal mental health services, which took place from June to August 2016. The data collection process involved all 58 English Mental Health Trusts and the aim of the project was to inform the Perinatal Expert Reference Group of the current provision of perinatal mental health services in England, covering both inpatient Mother and Baby Units and Community Mother and Baby Teams. The data collection covered 2015/16 outturn data, or in some cases, data as at a census date of 31.3.16.