At one earlier brief point in my professional life I sat on a UN committee that was drafting a policy statement. I was amazed at how, at that point it was a small room of people making changes and many of them were ESL - I was the only native English speaker in the room, and the only one with any sense that some things sound/read different in different 'Englishs' eg American vs UK vs international school English. Trust me, errors can be made - its entirely possible there was a huge debate about 'pregnant people' vs 'pregnant women', then someone was asked to shorten a section, then the entire context that made it clear they were talking about women in countries that don't have early pregnancy testing or where women don't routinely use contraception and where there are high levels of FAS as a result was lost. Or that everyone in the room thought that was so obvious that it didn't need pointing out.
They talk about teens. They're clearly talking about all teens, and basically trying to encourage zero alcohol consumption among all people entering adulthood to reduce/eliminate harmful use. I see on here, constantly, the references to people who aren't using contraception but somehow don't think they're 'trying' because they aren't charting their ovulation. So would assume that's what 'child-bearing age' is capturing, an area of concern rather than a blanket ban.
If it was a standalone recommendation that all women of child-bearing age shouldn't drink any alcohol, it wouldn't be a sentence in a standalone report it would be its own recommendation and would go through a different process.
I'm not saying its not rubbish, but unless they come out and double down on this, I wouldn't be inferring that the WHO has had a policy change and wants to stop all women drinking alcohol. I would think that an organisation with a multi-lingual staff team and multiple rounds of editing didn't pick up on the nuance of one sentence in the context it was written in, probably because they were focused on other more 'contraversial' parts of it.