Tagging babies was also mentioned in a conference in Cambridge in April, where an American 'expert' also spoke of keeping a register of babies' footprints. Secondly, tagging babies is not about stopping baby snatchers. If that were really the goal, it would make much more sense to tag doctors, nurses, hospital porters, fathers, etc. Or they could be given tags to carry in their pockets. Doors to maternity wards and nurseries could be made to open only for people carrying tags.
Many government buildings use a similar system already.
Obviously any whistleblower or spy could just cut the tag off. And any serious baby snatcher could do exactly the same. You might argue that alarms could be set to sound as soon as someone tried to cut off a tag. Surely snatching one baby is as bad as snatching any other baby. Or is a nurse going to punch in the number of any baby who's being taken home legitimately, so the alarm won't go off when it's taken out by its real mother.