gawd i thought id tripped and fell into the debate forum!
Emma - there are combination car seats that you can buy which are shaped more like a 0+ car seat kwim?
I have one for DD1 - it rear faces for birth + then goes rearward for 1year plus, 20/22lb + etc etc they are reclinable and they 'surround' the baby thus minimising the risks..the one i have is made by britax
The thing is, likeSteffi says, it depends on the child and their individual development..my daughter didnt go into her forward facing position until she was over a year old but that was coz she was utterly squashed...admittedly if you have a 20lb child whos 4 months old (wholly possible) I would say common sense should be the main stay in the descision so a four month old however big would not have the neck muscles to sustain a safe positionin a crash
The car seat i have is a combination car seat called the britax eclipse. they are more pricey but worth it in the long run...mothercare quite often do them on offer.... dont forget some LO's are much bigger physically than their weight says IYKWIM...my Lo is 5 months old, only 17lb but looks like a 7 month old baby...she was holding her head up by 4 weeks of age by herself (im not saying thats how you should judge im just saying that every baby reaches stages at different times regardless of age and weight)
The most important thing to remember is it dont matter half as much what position she faces as making sure its fitted correctly..coz even in the 'right' seat it aint gonna be safe in an accident if it aint fitted right..
when you come up sat have a look at mine...