In another era, suburban mums would chat to each other over the back fence sharing the trials and tribulations of parenthood. But those days are long gone, with many couples working full time, living far afield from friends and family and only on nodding terms with the neighbours.

Social media pages for parents have sprung up to fill the void and while Facebook exchanges can be a source of useful information, support and entertainment, they can also turn nasty surprisingly quickly when posts go rogue.

Emma Lovell, a businesswoman and mother-of-two from Queenscliff, was stunned by the level of aggression she witnessed in groups supposedly established to offer support.

"I would see the most hurtful comments on Facebook every day," she says. 

"Women would say things to each other online they wouldn't dream of saying in a face to face conversation. They just vent."

Lovell became so disenchanted with the cyber hate she witnessed, she recently set up her own Facebook group, Mumsomnia, with the aim of encouraging women to meet face to face.

RMIT University information technology lecturer John Lenarcic​ says social media can be a double edged-sword, providing great support but also fertile ground for bullying.

"It's almost like a Dr Jekyll and Mr Hyde world online," he says.

"In real life people can be perfectly reasonable but online they can be completely hostile."

Rachel Chappell​ was alert to this when she established the Facebook group North Shore Mums in 2012, hoping to make a few local connections as she was new to the area. Since then the group has grown to 20,000 members, publishing 200 new posts a day.

"Obviously, with so many members there are going to be differences of opinion," she says.

"Ninety-nine per cent of the time people are supportive and respectful but the other 1 per cent can be quite nasty and we don't tolerate that.

"The benefits of being able to share information and advice far outweigh the drawbacks of a small minority who just want to cause trouble."

Facebook groups for parents have exploded over the past five years. There are groups for parents in specific locations as well as those with particular interests. Posts are as diverse as the membership, covering everything from domestic violence to where to find a reasonably-priced plumber.

There are some topics guaranteed to spark heated debate  but even more prosaic subjects such as shopping centre car parks can get fingers tapping heatedly on keyboards.

When Justine Slapp​ co-founded Hills District Mums in 2013 she wanted to connect a few hundred mums in Sydney's north west. The group now has 13,000 members, 2000 posts a week, 15,000 comments on those posts and 14 moderators.

"I was a real control freak in the early days," Slapp says. "I would get really nervous about what people were posting."

Slapp does not believe in shutting down debate and avoids deleting posts unless absolutely necessary.

"People hate their posts or comments being deleted," she says. "You're taking away someone's voice; silencing them."

For all the outbreaks of bad behaviour online, there are many more examples of generosity, according to Anita Vitanova​, who founded Inner West Mums in 2013.

"Recently a mum posted that she didn't have a particular type of syringe she needed to give medication to her child," she says. 

"Another mum saw it, realised she had that type of syringe and drove it over to the poster."

Vitanova has found many of Inner West Mums' 17,000 members post about non-child related topics.

"When you are at home with a baby all day you do crave adult conversation," she says.

"You see some really intelligent discussions on the group – it's not all about teething and where to get the best babycino."

New to the Facebook mums' groups? Here's a list of landmines to watch out for.

Tread carefully

• Feeding: Doesn't matter whether it's breast or bottle, this is guaranteed to spark lively debate.
• Method of delivery: Drug free with dolphin music and essential oils? In the bath at a birthing centre? At home? In an operating theatre? There are plenty of ways to have a baby and just as many opinions about it.

Amber alert

• Education: Back in the day, choosing a school for your child was a simple affair. They either went to the local comprehensive high school or went private. Smart children went to selective schools. These days the choices seem endless and so are peoples' views on the matter.
• Paid work versus staying at home: Whether you've chosen to stop paid work to raise a family or raced straight back to the office, there's no easy answer. Life is complex and so is this question. 

Sound the emergency signal

• Vaccines: A casual post about new research on immunisation can unleash a torrent of opinion, some informed, some not so much. Most groups have guidelines about health-related posts. Some automatically delete any posts about the false link between vaccines and autism. 
• Circumcision: As with many sensitive subjects, there's not a lot of middle ground on this one. One person's medical procedure is another person's child abuse.