The move would be the most significant of a series of manoeuvres large and small, to exclude the population from civil rights protections and roll back the Obama administration's more fluid recognition of gender identity.
That's a little.dramatic. Changing definitions under which government agencies operate does not summarily "render 1.4 million transgendered people legally nonexistent", particularly given that, until a few months ago, gender and sex was, in fact, determined by biological traits identifiable by or before birth.
A spokeswoman for the Department of Health and Human Services (HHS) declined to comment on what she called "allegedly leaked documents" but cited a ruling by a conservative United States district judge as a guide to transgender policy.
Roger Severino, director of the Office for Civil Rights at the department, declined to answer detailed questions about the memo or his role in inter-agency discussions about how to revise the definition of sex under Title IX.
According to the memo, HHS would define gender as being "a biological basis that is clear, grounded in science, objective and administrable".
The news was met with fury by transgender activists, and a protest was held in New York's Washington Square on Sunday night.
While social mores enter into the debate, medical and scientific experts have long recognized a condition called "gender dysphoria" - discomfort or distress caused by a discrepancy between the gender that a person identifies as and the gender at birth.
No-one from the Trump administration has so far commented on the reports.
It is the latest effort by US President Donald Trump's administration to chip away at protections for the LGBT community. This is clearly another ideologically-driven attempt by the Trump administration to marginalize transgender people and force them into the shadows.
Unnamed Trump administration officials told the Times that HHS is preparing to present the memo's definition of gender to the Justice Department by the end of this year.
DHS has been arguing that "sex" doesn't include gender identity over the past year, and has, according to the Times, felt that the "lack of clarity" caused by inclusive Obama-era rules "wrongfully extend civil rights protections to people who should not have them". Anderson argues that gender can not be severed from biological sex, and that "taking our sexual embodiment seriously in public policy is not discriminatory"'.
In a 2016 ruling, Judge Reed O'Connor of the Federal District Court in Fort Worth, Texas, stated: "Congress did not understand "sex" to include "gender identity" " when it passed the Affordable Care Act, also known as Obamacare.