Thomas Hunter has been jailed for six years for causing the death of three-year-old Isla Wiggin by dangerous driving.
The court heard Hunter was travelling at 54mph and only tried to brake a second before running into the line of cars on the A34 in Oxfordshire.
Isla from Fleet in Hampshire, died in a collision on the A34 in Hinksey Hill, Oxfordshire, on 25 August. Her unborn brother also died as a result of the collision.
At the time Isla's family issued a statement saying she was "a loving and caring" daughter who "would have made an amazing big sister".
A lorry and seven cars were involved in the accident, which closed the northbound carriageway for almost 10 hours.
More top news
Philippa has the latest weather update for the east
Philippa has the latest weather update for the west
Explosives experts have detonated a World War Two mine found in Sussex.