The Royal Institution of Chartered Surveyors (RICS) said that constraints on affordability have also affected buyers, following significant rises in the cost of properties in recent years.
Up to the end of July, the most recent month for which data is available, 7,438 properties had been sold in Nottinghamshire.
It is a seven per cent drop compared to the same seven months in 2017, a picture reflected across the East Midlands, where sales were seven per cent down.
Across the UK, sales were lower in each month to July than in the corresponding 2017 month, and were down by nine per cent in total.
Simon Rubinsohn, chief economist at RICS, said: “Uncertainty about the economic outlook on the back of the never-ending Brexit negotiations has become an increasing drag on transaction activity in the housing market.
“The mood music amongst buyers has also been impacted by affordability constraints as hefty price gains over recent years have pushed ever higher the size of required deposits.”
The Government has encouraged the building of new homes to help deal with the housing supply, with an aim of developing 300,000 new properties a year nationwide.
It has also encouraged first-time buyers to purchase new builds.
It’s Help to Buy scheme offers favourable saving rates for first-time purchasers, and equity loans or shared ownership schemes at the time of purchase.
But between January and July, just 678 new homes were sold in Nottinghamshire, 22 per cent fewer than in the same period last year.
Second-hand property sales also decreased by five per cent to 6,760.
Mr Rubinsohn continued: “The Government’s Help to Buy scheme has provided some support for the new build sector but this has left the second-hand segment even more exposed.
“On top of this, a lack of stock for the sale in this part of this market has compounded the problem.
“Existing home-owners are staying put for longer meaning there is less property available for prospective purchasers to view.
“Meanwhile, in the background is the concern that the cost of mortgage finance is likely in due course to become dearer.”
The average property in Nottinghamshire sold for £176,715 in September, five per cent more than a year previously.
First time buyers paid an average of £147,286.