The average subscription to a Junior Isa was £1,614 with 89 per cent investing a lump sum and 68 per cent investing in at least one fund.
Some 25 per cent made regular contributions into their account and 15 per cent made regular and lump sum contributions.
Popular fund purchases included First State Global Emerging Market Leaders, Invesco Perpetual Income, M&G Recovery and Newton Asian Income.
Some £100 per month saved into a junior Isa for 18 years could grow to £38,000 assuming a six per cent annual investment return while £300 per month could grow to £114,000.
Six million children were eligible for Junior Isas at the outset in November 2011 then 800,000 were newly eligible each year from birth.

Danny Cox, head of advice at Hargreaves Lansdown, said: "Junior Isas have had a slow start but this is not surprising given the economic climate. New products always take time to bed in and not all providers were ready at launch."
Some 14.3m accounts were opened for ordinary Isas with 80 per cent being cash Isas. The average subscription for a cash Isa increased from £3,198 to £3,330 while stocks and shares Isas subscriptions increased from £4,571 to £5,490.
Mr Cox said: "The level of investment in Isas shows people recognise the importance of making the most of their legitimate tax breaks. Isas are a phenomenal success story with half the adult population of the UK investing in an Isa account."