The women were upset because one of the vendors was asked to cover-up while breastfeeding last week.
Natalie Arsenault said she was shocked when she received an email from the manager of the Moncton Market, asking her to cover-up while breastfeeding her son. The manager told her they received a complaint.
Arsenault said she's comfortable nursing while she works at her kiosk. But she said incidents like this discourage other mothers.
Arsenault said breastfeeding rates in New Brunswick are low.
"The few women that do breastfeed tend not to do it in public, because it is so stigmatized and it is so over-sexualized, and so we tend to hide," she said.
Arsenault says she's pleased with the show of support from other mothers.
"This is just a peaceful way to educate people on breastfeeding so it just gets people talking and it's not a protest of any kind," she said. "It's just a simple act of unity for breastfeeding mothers."
Sonya Malaborza participated in the nurse-in to show her support.
"There's a lot of public discomfort, cultural discomfort about seeing a woman nursing in public," she said. "Perhaps we need to work to change that a bit."
"We're sort of conditioned, you know, society is all telling us to do it, to do it, just don't do it in front of us," said Jacques Belanger, whose wife participated in the demonstration.
City of Moncton spokesperson Paul Thomson admits asking Arsenault to cover up was a mistake.
"It's an opportunity for all of us to learn and to understand the rights of nursing mothers and I think that's been the case in the last few days is people are becoming more aware of the issue and sensitized to it."
Thomson said the city fully supports breastfeeding in all of its facilities.
Breastfeeding in public is protected under the New Brunswick Human Rights Act.