For women now in their 50s this had doubled to two people, usually their partner and their own mother.
Siobhan Freegard, founder of Channel Mum, said: "The younger generation are used to sharing every aspect of their lives, so why not birth?
"Many women feel it is their biggest achievement and so want to share the moment with all of those closest to them.
"The crowdbirthing phenomenon may not suit everyone but being part of the birth is an honour and privilege which unites friends and family like nothing else."
Mothers-in-law are now the most popular birthing supporter after the mum's partner and mother, they survey suggests. One in 25 even chose their own father to be present in the delivery room.
But the research also shows there is a downside to giving birth in front of an audience.
Mothers are increasingly refusing to take pain relief because they fear they will be judged. One third of the women surveyed cited social pressure as a reason to have a birth without painkillers, complaining that others would regard them unfavourably if they did otherwise.
One in five said they felt that opting for a caesarean section would make them feel as though they had "failed at giving birth".
Adding to the stresses of new mothers are women who write about their births on social media and talk airily of bringing new life into the world, and celebrities who make giving birth seem effortless.
Some 15 per cent of mothers said they felt under pressure from stars who have apparently sailed through labour, such as supermodel Gisele Bundchen, 35, who said her eight-hour labour "didn't hurt in the slightest" and claimed her newborn son didn't even cry.
The rise of social media means that the moment of giving birth, once an intensely private event, is now being shared all around the world.
Many mothers take selfies with their baby just moments after delivery and post the picture on Facebook and Twitter.
Some are even hiring birthing photographers to capture every intimate moment.
- Daily Mail