The child disclosed problematic sexual behaviour had occurred with her friend.
The woman knew she needed to speak to the other parent about it.
"The mother looked in complete shock," she told AAP.
"I tried my best to reassure her, explaining I understand these types of things can happen between children and to try not feel embarrassed.
"The conversation was closed down to some degree because another parent parents differently, and doesn't talk about these things with their children."
The two mothers initially worked together to develop strategies to keep an eye on their children, but the behaviour continued until the girls were separated completely.
The woman, who asked to be anonymous to protect her daughter's identity, had worked to educate her daughter on healthy touch and body safety.Â
She said her child sometimes wanted to participate in the activities, and other times did not.
"My daughter shared her feelings of embarrassment and shame and often our conversations were stopped with 'I don't want to talk about this anymore'," she said.
Looking back, she wishes there had been more resources available, access to support services and that parents could talk openly about these issues.
"It's a conversation parents don't want to have, because it's very taboo," she said.
"They think it's deviant behaviour, and it's not ... it's just not the way they're meant to be behaving at that age."
A survey of more than 8500 Australians aged 16 and over found 28.5 per cent had experienced child sexual abuse, with nearly half of reported abuse carried out by people under 18.
An Australian-first digital resources hub has been developed to equip parents, young people and practitioners with information to recognise, prevent and respond to harmful or problematic sexual behaviours in children.
"We have built the website with one simple message: everyone has a role to play to keep children and young people safe from harm," project lead Kenny Kor said.
"We can't wait until harm has occurred to act, we also need to provide help early and prevent problematic and harmful sexual behaviour."
Together We Can, which officially launched on Tuesday, was created by University of Wollongong researchers, with funding from the NSW government as a step towards ending violence against women and girls.
Dr Kor and his team identified more than 500 resources in Australia on preventing or responding to problematic or harmful sexual behaviour in children.
These have been studied to align with evidence on issues from tech-facilitated harm to sibling sexual harm, and consolidated into resources tailored to children, parents, or practitioners like social workers and teachers.
"You don't need to have specialist knowledge or skills to prevent harm and to respond to harm," Dr Kor said.
"You can start by learning more about the topic, so that you can be prepared to act when you see or hear something concerning."
The resource comes as concern grows over algorithms promoting toxic masculinity to boys, and high rates of sexual strangulation in young people.
"I do think that we need to act now before all of these influences that young people are being exposed to become entrenched in the way they understand gender equality, and in the way they treat women and girls," Dr Kor said.
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
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