Audiences flocked to see the hotly-anticipated Fifty Shades of Grey film on its opening Valentine’s Day weekend, as it took a record-breaking £13million.

And it seems midwives in Leeds are well aware of the erotic movie’s potential for a baby boom nine months later, with a hospital staff room sign warning employees to ‘book your annual leave now’.

The notice said: ‘Important information for midwives. The movie Fifty Shades of Grey is being released February 13, 2015 + 40 weeks = November 20, 2015. Book your annual leave now.’

The origins of the sign are unclear, although it is believed to have been posted on February 12, the day before the hit film based on the novel by EL James was released in cinemas.

A report in The Sun by Lucy Gardner claimed the notice was seen at St James’s University Hospital in Leeds, although a hospital spokesman said she could not find any evidence to support this.