The thing with centiles is that they are for formula fed babies and breast fed babies have a seperate chart but it costs more! BF babies don't really follow the FF chart and it can cause a lot of problems when a BF baby isn't doing too well - trust me, I've been there! I can't imagine 50th centile let alone 75th! Tink is on 2nd centile IF you adjust her age by eight weeks, if you go by her birth age she isn't on the chart (but I made a fantasy line when I was bored on Saturday to see how that looks and she's getting close to the chart!)