The woman in the Market Drayton area was eight months pregnant when her former partner Daniel Tandy, 27, knocked on her door and knocked her to the ground when she answered, before raining down blows on her with a hammer.
She was left with facial bone fractures and a broken wrist as well as bruises around her body, but her unborn child survived.
Tandy, of Brook Road in Oldbury, had travelled from the Birmingham area to attack the woman after texting others about her pregnancy in the preceding weeks, Shrewsbury Crown Court heard.
He has already pleaded guilty to causing her grievous bodily harm but Tandy's new partner, Joanne Terry, of Barnard Close in Birmingham, and his associate, Kyle Emery, of Tennal Lane in Harborne, are now on trial accused of helping him.
The court heard on Tuesday that Terry, 44, is accused of perverting the course of justice by providing a false alibi to police while Emery, 21, denies taking part in the grievous bodily harm by driving Tandy to his victim's home in Market Drayton.
Emery's Vauxhall Corsa was detected on roads between Birmingham and Market Drayton on the night of the assault, October 10, 2018.
It had different number plates at different stages of the night, with one set of plates cloned from an unrelated car in Stoke-on-Trent.
In addition, telephone activity was picked up between a phone belonging to Emery and one belonging to Tandy – the latter phone remaining at Tandy's home in Birmingham.
The prosecution case, represented at trial by Mr James Dunstan, is that Tandy could have left his phone at home deliberately as a diversionary tactic because he was aware of the authorities' ability to detect phone activity.
Terry, represented by Mr Anthony Bell, told police that Tandy was at home on the night of the attack. Her case maintains that he could have left the home for some time without her knowledge.
Meanwhile Emery, represented by Ms Kelly Cyples, denies taking part in the grievous bodily harm by being the driver on the night in question.
A jury was sworn in on Monday, and on Tuesday the trial heard evidence about the phone activity and the movement of the car.
Tandy will be sentenced for the assault after the trial of Terry and Emery concludes.
In video interviews heard by the court, the victim of the assault said that Tandy had previously threatened to burn her house down and was a "violent person".
The trial continues.