The current guidelines are that "They must be rear-facing until your child is over 15 months old. Your child can use a forward-facing child car seat when they’re over 15 months old."

Children's bones in their neck are soft until around aged 4 and are not developed enough to protect the spinal cord. As a child's head is 25% of their body weight so we would need to prevent their head being violently thrown forward in a crash, as this could lead to internal decapitation.

When forward facing in a crash their head is subjected to stress loads of 180 to 300kg. When rear facing they are subjected to only 40 to 80kg which is a huge difference. 

Rear facing lowers the risk of death or serious injury to 8% whereas forward facing that risk of death or injury increases to 40%.

It is a no brainer that we should be protecting our children at all costs and it should therefore be illegal to forward face before the age of 4 unless under certain circumstances, such as a disability. 

More education on car seat safety is definitely needed to protect our children.