What was once an online conversation between new mothers, sharing stories and advice about sleepless nights and potty training, has evolved into a multibillion-dollar industry.

Mommy bloggers, who these days mostly post their stories along with pictures on Instagram, are a major force in so-called influencer marketing. But using your social media channels — and sometimes your family — for advertisements comes with challenges.

Mommy bloggers are such effective spokespeople for brands because they speak to the women who already trust them, says Jane-Michèle Clark, a marketing instructor at York University who led a study, still in progress, that examined influencer marketing.

"There's a huge connection between the person following them and the mommy blogger," says Clark. "They start to value her opinion on multiple matters, whether it's child raising or the products that they sell."

Watch: Bloggers describe how they make money

Toronto mom bloggers Alana Kayfetz, Elena Sikorski, Ivy Chen and Zehra Allibhai talk about how they generate income through ads, and how they choose brands they want to work with. 1:24

Average mom influencers whose followers number in the thousands can expect to make $50 to $100 per sponsored post featuring a product, and juggle three or four ongoing contracts with brands. Top bloggers can make $5,000 per sponsored post.

The ability to stay at home with their children while still generating income makes this Mommy Blogging 2.0.

'Regular mom like me'

Anna Sinclair, a Toronto mother of two boys, aged two years and seven months, started blogging after her first son was born. A former singer and songwriter for the Disney Channel, she says she was missing a creative outlet. She started writing and posting pictures of her young family, and says the support she received was overwhelming.

"You're so busy and things are so difficult," says Sinclair, welling up as she remembers those days. "Complete strangers can be there for you when you need them the most. And just the advice — I find that my personal friends they don't give me as good advice as some of the people that I talk to in my Instagram direct messages."

Soon, companies started sending her products — a packet of diapers, mashed baby foods, a detergent brand — to feature on her blog for remuneration, in money or goods. She couldn't believe it.

"I thought it was just the Kim Kardashians of the world, I didn't think that a regular mom like me would get paid to do this."

Little by little, Sinclair educated herself on the going rates for mom influencers, based on her number of followers and the engagement and discussion her posts generate. She says she and her husband carefully chose the brands they felt comfortable working with, in keeping with her blog's focus on an organic and "clean" family lifestyle.

It was a steep learning curve, and there were some up-front investments — a good camera is a must, she says — but Sinclair says she wouldn't trade it for the world.

"We always talk about how this is the best thing that's ever happened to us," says Sinclair. "We can still make money and do this but not have to be gone away from our kids all day."

A cautionary tale

But mixing family life with big-brand deals can be tricky business. Pictures and stories of children are at the core of mommy blogging. Most of the children are too young to consent to having their images used to generate a following or sell products, prompting debate around children's rights over their "digital footprint."

Heather Armstrong, a popular early adopter of mommy blogging who has been writing for 15 years, experienced a stark reminder of how her sponsored posts affected her children.

"They wanted us to do outings in the car and go places and play word games in the car, and my kids hated it," Armstrong said via Skype from her Salt Lake City, Utah, home. One try after another at the video that would please the sponsor, and her four-year-old daughter started pleading with her to stop.

"She looked up at me as we're getting into the car and she had tears just pooling in her eyes and she's like, 'Please, Mom, don't make me do this!'"

The incident made Armstrong quit blogging altogether for two years. She now encourages mom influencers to handle brand relations with caution.

"They want your authentic voice, the brand does, but they want to control your authentic voice — and they have a lot of rules and regulations about what you can and can't say, and can and can't show."

Armstrong is back to blogging now, but she has some new ground rules, like only working with brands she feels comfortable with, and running all her posts that feature her kids by her daughters, now aged nine and 15.

Authenticity vs. advertising

That's not the only balance mommy bloggers will have to strike as their business expands. Research shows that the very following that earned mommy bloggers their ad revenue to begin with may start to erode if a blogger posts too many sponsored posts.

Watch: Bloggers describe how they feel about putting their children's images online

Toronto mom bloggers Alana Kayfetz, Elena Sikorski, Ivy Chen and Zehra Allibhai talk about how they balance their concern for their children's privacy with sharing family stories online. 1:14

"One of the things that we were looking at was authenticity — a lot of the blogs got started because moms were sharing their experiences, and new moms and moms-to-be wanted to see how real people people just like them were coping with becoming a mom," says marketing professor Clark.

"But, according to our research, the more that these bloggers shift from providing an experience, showing their personalities, sharing their family moments, to promoting products they use with their kids and their families, that level of trust is starting to diminish."

Sinclair believes she can continue to walk that fine line by only working with brands she truly likes, and not bombarding her followers with sponsored posts. As for her children, she says that if at any point they expressed discomfort with what she was doing, she would quit blogging in a heartbeat. But for now, the life of a paid mommy blogger is treating her family well.

"We get to travel, we get to experience a lot of things that other people don't get," says Sinclair.

"Not a lot of traditional jobs are available out there anymore, and this is a fantastic opportunity for women and moms not only to empower themselves but to also have their own business, work on their own terms."