“This administration is bringing back common sense and restoring biological truth to the federal government,” Kennedy said in a statement.

The memo defines terms such as sex − "a person's immutable biological classification as either male or female" − and female versus male.

Kennedy's announcement comes a week after he was confirmed to lead the Department of Health and Human Services over objections from Democrats and medical professionals who criticized Kennedy's history of vaccine skepticism.

It also comes in response to an Inauguration Day executive order by President Donald Trump declaring that the federal government would recognize only two sexes. The order tasked HHS with delivering guidance for enforcement.

HHS also unveiled a new web page titled "Protecting Women and Children" with a banner video by college swimmer and influencer Riley Gaines, known for her advocacy around keeping transgender athletes out of women's sports.

Related:'Biologically inaccurate': Judge blasts Trump policy to ban transgender people from the military

"The clarity and decisiveness of this administration sends a strong, clear message to women and girls across the country that we matter," Gaines says in the video.

Trump has sought to overturn Biden administration era policy on a mix of gender-related issues, including reinstituting a ban on transgender people serving in the military.