The 6 month+ formulas were designed in the 80s; advertising of first stage formula was still legal when they were invented so its a myth they were designed purely to circumvent advertising laws on first stage formula BUT they were primarily invented to tap into a different type of market and profit accordingly as opposed to there being any real nutritional need for a different type of formula aged 6 months+. Many countries, including the US don't have any 6 months+ formulas on the market though they may have toddler milks. The top claim of the follow on milks is they have the same amount of vitamins/minerals than first milk but in less volume of milk so baby can have less per day and still get as much vitamins and minerals if they were on say 5 bottles a day-but the concentration in the follow on milk of vitamins and minerals is only a teeny bit more than the first milk. Also some vitamins and minerals are less in your typical follow on milk, as opposed to the first milk, take vitamin C for example. There are also some B vitamins missing from follow on milk. The follow on milk does contain more iron but the iron in formula is fairly poorly absorbed and a recent study found that in some cases babies on formula with very high iron levels were less healthy and developed less well in the long run; so its questionable if very high levels of iron are a good thing xx