A warning has gone out to people wanting to save a hospital maternity unit - "use it or lose it".

Midwives at the Princess Royal Hospital in Haywards Heath are joining forces with GPs in Mid Sussex in a campaign to increase the number of births at the hospital by at least 1,500 a year.

There were about 2,200 babies born at the hospital in 2006/7 and the number is expected to be around 2,400 this year.

Brighton and Sussex University Hospitals chief executive Duncan Selbie said if the number of births at the hospital reached a minimum of 3,500, it would have a stronger case to make.

The hospital wants to keep its consultant- led services and not be downgraded to a midwife-led unit.

Units need to carry out enough births a year to ensure specialist staff have enough cases to work on.

The hospital is at risk of losing the consultant maternity services as part of a planned shake-up of services in the Fit for the Future public consultation.

Campaigners are hoping that in a few years' time the Princess Royal will keep its existing consultant service while running a separate midwife-led maternity unit on the same site.

Midwife Sally Fox said: "This would be ideal and give women a much greater choice. It could also lead to more people considering home births.

"If the Princess Royal lost its consultant- led service then women are not going to be happy about going for a home birth without back-up nearby.

"The most important thing now is to get the message across that our unit is not planning on closing at any time soon and actually we want to see more people coming here. The more we can get, the greater our chances."

The move is being backed by GPs across Mid Sussex with Newick GP Herry Ashby writing to colleagues in the county urging them to consider referring patients to Haywards Heath.

The Fit for the Future consultation, drawn up by West Sussex Primary Care Trust and Brighton and Hove PCT has put forward three options.

These put facilities such as accident and emergency and maternity at risk in Haywards Heath, Worthing Hospital and St Richard's Hospital in Chichester.

At a Brighton and Sussex University Hospitals board meeting this week, members responded to the consultation.

They want the Princess Royal keep its A&E services and for it to continue to provide urgent care when needed while working closely with its fellow hospital, the Royal Sussex County in Brighton.

Chief executive Duncan Selbie said the indications for the future of these services were promising but warned the maternity issue was more difficult to meet.