Legislation requiring sex education in Massachusetts schools to be inclusive of all identities and use “medically accurate, age-appropriate, and comprehensive” information started advancing Thursday toward a vote in the Senate, which could come next week.

Supporters of the proposal, dubbed the “Healthy Youth Act,” said the law will make clear that sex and relationship education in Massachusetts must cover LGBTQ+ identities and experiences while emphasizing consent in relationships.

Sen. Sal DiDomenico, the Senate sponsor of the bill, said the people who believe that people have their “heads in the sand” if they believe students are not talking about sex and gender.

“Making decisions without accurate information … have short-term and long-term consequences,” DiDomenico told the Herald. “That could be teen pregnancies, (sexually transmitted infections), and getting into relationships that are unhealthy for them, and not finding a way out of unhealthy relationships. This is a bill that’s really important, in my mind.”

The proposal has a long history on Beacon Hill. DiDomenico has filed his version each session since 2015, with the Senate passing it four times. Rep. Jim O’Day, a West Boylston Democrat, has put forward a similar bill on the House side, though the chamber has never taken it up.

A likely fifth round in the Senate comes months after the Board of Elementary and Secondary Education approved the first update to the state’s health and physical education framework in 25 years, which Gov. Maura Healey pitched as more inclusive of “gay, queer, and trans students’ identities and needs.”

The legislation that started moving through the Senate Ways and Means Committee, often a clearing-house for bills destined for a floor vote, requires that sex education curricula include age-appropriate information on the human anatomy, reproduction, sexual development, the benefits of abstinence, and the effective use of contraceptives.

Sex education classes must also cover ways to discuss safe sexual activity and gender identity and sexual orientation, “including affirmative recognition that people have different sexual orientations, gender identities and gender expressions,” a summary of the bill sent to senators said.

A city, town, regional school district, vocational school district, or charter school that opts in to providing sex education must do so in a way that focuses on building healthy relationships with discussion about consent and boundaries.

The bill also mandates that the words “consent,” “gender expression,” “gender identity,” and “sexual orientation” used in educational materials be consistent with definitions provided by the Commission on Lesbian, Gay, Bisexual, Transgender, Queer, and Questioning Youth.

But some parents have expressed opposition to the bill, including at an October 2023 Education Committee hearing. A handful of opponents at the hearing alleged the bill would promote “graphic sexual content.”

DiDomenico said those criticisms of the bill have been “debunked” on countless occasions.

“The scare tactics that have been used in the past to try to say this bill is something that it is not have been said over and over and over and dispelled each time,” he said. “The medically accurate, age appropriate piece of this bill is very, very important. And we have experts in the field who are identifying what is age appropriate and what is medically accurate.”

Senate Democrats propose handing the Department of Secondary and Elementary Education the authority to determine the minimum education and training for sexual health education instructors.

Public, vocational, or charter school districts that teach sex education must adopt a written policy that ensures parents and legal guardians are notified of the planned curriculum and are given the opportunity to pull their children from all or part of the instruction.

Students who are taken out of sex education cannot be disciplined, according to the summary of the bill. And district must provide “an alternative educational activity” for students whose parents or legal guardians removed them from sex education.

Districts are also required to submit data to the Department of Secondary and Elementary Education on the implementation of sexual health curriculums, including how many hours are spent on instruction and how many students opt out.

Seventeen other states require sex education be medically accurate and 26 require instruction be age appropriate, according to Senate leaders.

DiDomenico said he and other supporters have worked on the bill for several sessions and have built up strong momentum in the past. This session’s bill does not have any major changes compared to previous versions, he said.

“Talking to folks this time around, I feel like we have a very, very, very good shot. I’m optimistic this bill is going to be signed into law,” he said.