A Hobart man has avoided jail for bashing a pregnant woman who intervened in a children's squabble.

The Supreme Court in Hobart was told Leigh Watson Penniston, 39, went to Lisa Maree Shelton's Risdon Vale home last November with the intent of injuring her.

Penniston's 11-year-old son swapped his BMX bike for Ms Shelton's son's mobile phone and a squabble escalated between the two families because of the trade.

Penniston bashed Ms Shelton who was four months pregnant at her front door, punching her repeatedly to the head and body.

When she screamed at them to stop because she was pregnant, he yelled "we don't care if we kill your baby".

Penniston received a six month suspended prison sentence and a $1000 fine.