Agree with you 100% OP - this only causes people to doubt the WHO further.
The only (semi-reliable) stats I could find on FASD levels in the UK was a study conducted with mothers who gave birth in Bristol in the 1990s, in which up to 17% of the babies showed some symptoms of FASD (bearing in mind FASD symptoms can overlap with other issues not related to alcohol): www.bristol.ac.uk/policybristol/policy-briefings/fasd-uk-prevalence/
Trends from the UK show that average alcohol consumption has decreased over the past 2 decades, meaning if anything the likelihood of babies being born with FASD now is even lower.
We have early detection pregnancy tests now that can pick up on pregnancy sooner than ever. It would be better to advise regular testing and limiting alcohol consumption in the case of potential pregnancy during the 2 week wait, rather than seeking to prevent all women of child-bearing age (regardless of the status of their sexual activity and contraceptive use) of drinking altogether!
As stated in their report, it's predominantly men who are the problem drinkers and yet the report doesn't recommend that they go tee-total. In the UK, it's men (and predominantly older people) who are the bigger drinkers - even with being a nation of "drinkers", young women are being sensible with their alcohol consumption:
www.statista.com/statistics/369808/alcohol-units-consumed-by-gender-and-age-in-england/
www.statista.com/statistics/369868/weekly-alcohol-consumption-by-gender-in-england/
I think, as PPs have noted above, this poor advice from the WHO signifies how they really think of women. It's unscientific clap-trap and very poor form