A woman who sent sexually explicit photos and videos of her daughters to their dance teacher in order to further their careers has been jailed.

The woman, who cannot be named, sent at least 100 photos and two videos of the girls to Grant Davies, who was the director of the RG Dance school at Chiswick in Sydney.

Many of the photos showed the two girls, who were aged under 14 at the time, naked in their bedroom or bathroom.

Some focused on their genitals and others featured the girls in sexually suggestive poses.

Judge Peter Zahra sentenced the woman to three years and six months' jail with a non-parole period of 18 months.

Earlier the Downing Centre District Court heard the woman had been obsessed with the girls' success and wanted to do anything that could enhance their dancing careers.

In one text message to the woman, Davies said: "OMG, I want more pics. Can she look through the lens?"

The woman described Davies as "intimidating, overpowering and abusive".

She said: "I knew it wasn't right. I didn't know how to stop."

The court heard she took no action against Davies because she feared her husband's reaction and that her daughters would be named in the media.

She also claimed she feared Davies and was scared he would put her daughters to the back row in performances or leave them out completely.

Davies has yet to stand trial on more than 60 child sex offences.

Judge Zahra said: "I do not accept the offender acted in fear of Davies."

He also said her previous mental health problems, including depression and eating disorders, did not excuse her moral culpability.

"The offender was in a position of trust," he said.

"The victims were vulnerable.

"Because of her own obsessions with fame, she knowingly exploited her children."

The judge said it was not clear whether the woman now realised the damage she caused her two daughters.

The woman's lawyer, John Sutton, said her husband had continued to support her.

"He sees his wife as a mother to his children, and it's a very regrettable and entirely difficult situation and, yes, he stands by his wife," Mr Sutton said.