The chief executive of the Royal College of Midwives has slammed foetus parties as a way of "commercialising" pregnancy and childbirth.

At the parties, guests gather to watch 3D and 4D private scans of foetuses. The events are believed to be gaining in popularity in Britain.

In an article on the BBC website, Professor Cathy Warwick, claims that the number of mothers over the age of 40 increased by 71 per cent between 2001 and 2010.

Due to the increasing number of older mothers, maternity services are under increased pressure because of the greater risk of complications.

Pressure on maternity services has further risen because of the growth in foestus parties, she said. The parties increase the "expectation for mothers which midwives then have to deal with", she claimed.

The parties involve men and women gathering to exchange 3D and 4D photos of their unborn babies.

"There are companies across the country that provide gifts for parties featuring images of the foetus from a fridge magnet for £3 to a teddy with 3D scan image for £15," she said.

"Some companies provide a champagne celebration scan package for £165 and a VIP scan package for £185. This is a far cry from the original purpose of ultrasound."

Despite the initial introduction of 3D and 4D technology for health and early-intervention purposes, Warwick said it was being used as a "'consumer tool' which raised ethical questions.

Jan Steward, co-founder of Ultrasound Direct, which offers scanning services and commemorative gifts, told IB Times UK: "Our services are not readily available on the NHS bar a 10-minute session at 12 weeks and a 20-minute session at 20 weeks.

"There are times when it becomes extremely valuable; a common instance is when grandparents with terminal diseases may not be alive to see the birth.

"The NHS is occasionally dubious about allowing the unborn child's siblings in to the scan, whereas we stress the importance of family."

Steward also highlighted the importance of using regulated ultrasound operators if you're considering having 3D or 4D scans taken.