Just to clear up a point about how long 6 months weaning has been under discussion:
In the 90s WHO and UNICEF disagreed about what to recommend. Looking at the same evidence, UNICEF took the "safe" route and recommended 6 months; WHO took the "minimalist" route and said 6 months is best, but 4 months is probably OK.
This disagreement drove everybody crazy, especially people who worked for both organisations. Hence, in 2000, the decision to have a huge review of current knowledge to try and clarify the point.
This was done, and when more recent evidence was taken into account, it became clear that the evidence was in favour of 6 months. Accordingly, WHO changed their recommendation to purely 6 months, as it is now.
So just to summarise: WHO have recommended 6 months for many years, but until 2001, didn't actively discourage 4 months. They are now convinced that there is good evidence for 6 months.
THIS RECOMMENDATION IS FOR DEVELOPED AND DEVELOPING WORLD BABIES.
(Sorry to shout, but if I hear the myth about developing world only one more time I will scream!)
I'm mystified about why people want to argue about this. We, as mums today, have access to better information about what's best for our babies than any other mums in the entire history of the human race.
Why would you want to ignore it?