The original proposal dates back to 2019. For the nerds in the audience, here it is: https://www.unicode.org/L2/L2020/20190r-swollen-belly-emoji.pdf

Choice quote:

One’s sex does not dictate the capacity to care for children in the home or work in the market​. In the same way sex equality law has aimed combat harmful sex stereotypes, there are a great deal of parallels regarding how one’s sex does not dictate the capacity to cary children.

This is not a new phenomenon. Pregnancy​ has been indiscriminate of gender throughout history but it is only now being formally recognized. ​The British Medical Association’s (BMA’s) advises to use ‘pregnant people’ instead of the stereotype term ‘pregnant woman’. And, although ‘a large majority of people who have been pregnant or have given birth identify as women’, there are intersex men and transmen who get pregnant.

Jessica Clarke, a law professor at Harvard University, suggests that, ‘law could see pregnancy not as something that only happens to women’s bodies, but also as a bodily condition experienced by people who do not identify as women’.

Interestingly, the proposal does acknowledge this emoji can be used for things like being full after eating Chipotle.