The Catholic Church has helped fund a full-page newspaper advertisement that has been slammed as fear-mongering by the families of transgender Tasmanians.

Key points: A bill making gender optional on birth certificates is set to be debated in Tasmania's Upper House this week

A bill making gender optional on birth certificates is set to be debated in Tasmania's Upper House this week The Tasmanian Coalition for Kids took out a full-page ad newspaper ad, it would have "serious implications for children's and women's safety"

The Tasmanian Coalition for Kids took out a full-page ad newspaper ad, it would have "serious implications for children's and women's safety" Transgender advocates say the ad was "uneducated" and has caused harm to families

A group called the Tasmanian Coalition for Kids has been formed in the lead-up to the Upper House debate on amendments to the Births, Deaths and Marriages Registration Act that would make gender optional on birth certificates in Tasmania.

The group took out the ad in a Hobart newspaper on Tuesday, claiming the new laws could compromise the integrity of people's identity, have serious implications for children's and women's safety and make it difficult to get a passport.

The Tasmanian Coalition for Kids is made up of the Archdiocese of Hobart, the Catholic Women's League, members of women's network Women Speak and anti-same sex marriage campaigners.

In a statement, the Archdiocese of Hobart confirmed the Catholic Church contributed financially to the ad.

Coalition spokesman Ben Smith said the aim of the ad was to encourage Tasmanians to write to legislative councillors and urge them to form a parliamentary committee that would hold public hearings on the legislation.

"We believe that it's very complex law and there are amendments upon amendments that have been submitted," Mr Smith said.

"We're concerned for the potential for bad law to emerge but we're also concerned that there's a fair bit of public concern and that hasn't had a chance to get an airing."

Neither the Archdiocese nor Mr Smith said how much the newspaper advertisement had cost.

Transgender advocate 'gobsmacked' by newspaper ad

This ad ran in a Tasmanian newspaper on Tuesday. ( Supplied: Tasmanian Families for Trans Kids )

Tasmanian Families for Trans Kids spokeswoman Candace Harrington, who is the mother of transgender child, said the advertisement was "uneducated" and had caused harm to families.

"I was gobsmacked," she said.

"There's no implications for children's and women's safety, various information that they've put here is wrong.

"I think it's just trying to put a negative spin on it, that's the aim I think, just to put fear into everybody."

Ms Harrington said she was hoping to speak to Mr Smith about the ad.

"I am a Catholic and I am concerned about the message being sent to parents with transgender children in Catholic schools, given Mr Smith's group is backed by the Catholic Archdiocese."

She said there was no need for public hearings on the issue, as MLCs had received extra briefings and information on the amendments over the summer break.

"This is for our children, so our children can be kids in the way they want to be."

Mr Smith said his group was not fear-mongering.

"We're just interested in making sure there's good law that emerges," Mr Smith said.

The Marriage Amendments Bill will be debated in the Upper House this week.

Windemere MLC Ivan Dean has already indicated he plans to push for the issue to go to a committee on Thursday.

It is unclear if he will have the support of other members given some MLCs became emotional last year when they realised the bill would not be passed in 2018, and instead delayed until this year.

The bill was amended by the Opposition and the Greens with the support of Speaker Sue Hickey in the Lower House last year, in a bid to remove discrimination against transgender and intersex people.