https://www.ucu.org.uk/article/12037/Gender-discrimination
Maternity rights get a mention at the bottom of this page - but just a link to a guide.
Not as important as the more hot button issue of menopause, which is below FGM.
Obviously FGM is a very important issue, but is it more relevant to a UK union for academics than maternity rights?
To be fair, right at the top of the page they talk about the gender pay gap.
"Academic gender pay gap will take 40 years to close
It will take 40 years to close the academic gender pay gap, warned a 2017 report from UCU. The report reveals that, in 2015/16, UK universities had a 12% overall gender pay gap for academic staff, compared to 12.3% in 2014/15 and 12.6% in 2013/14:"
But in this short summary, they can't quite mention who is adversely affected.
I suspect it's politically difficult for them to link maternity and pay and analyse the uneven material impact of becoming a parent on men and women. That might be cis heteronormative.