The problem with guidelines is that they tend to be over simplistic. Co-sleeping is not a SIDS risk, it's actually been shown to reduce the risk of sids. Its an overlying risk. But when officials want to get a message out they have to keep it down to short sound bites. Everyone knows what SIDS is, not everyone (sadly) would understand what "overlying" is. Someone here also wrote that the original "Back to Sleep" campaign was a Back or Side to Sleep campaign but it was too confusing!
The fact about weaning is that there are studies that say early weaning causes allergies and/or intestinal troubles and there are studies that say weaning late causes allergies or intestinal troubles. Even the scientists DO NOT KNOW.
Someone else already posted about it but there is a study going on right now as we speak to see whether early weaning will prevent allergies to common food allergens. That does not speak to the subject being closed to me.
The scientists actually say there is evidence that early weaning MAY be a contributing factor and CAN cause allergies and/or intestinal troubles. They say there is a RISK of these things happening, and it's a calculated risk you should be aware of because often times, these problems don't crop up until later in life.
Even though a baby may seem 'perfectly fine and healthy and happy' at 10 months when they were weaned at 10 weeks, that doesn't mean that the damage hasn't occurred internally at that point, even if it will only manifest noticeably years down the road.
I don't think that most, if any posters here speak in absolutes saying that IF you early wean, THIS WILL happen, and the authorities and scientists most certainly do not do so. All they do is point out the related RISKS that are stated as reasons to be cautious about weaning before 6 months, and moreso before 4 months.
To be honest, it seems to me that it's more often the case that I hear someone who has early weaned throwing a hissy fit about everyone telling them their baby is going to be full of allergies and intestinal problems and obese and grow a third arm and an extra eye and hair on the palm of their hands because they dared to wean early and how dare they!?! It amazes me that these histrionics and absolutes usually come from the 'other side' of the debate on early weaning and rarely, if ever from the proponents of following the guidelines and recommendations, yet it's the 'wait until they're close to 6 months' posters that catch hell for it.