She was talking to her husband on FaceTime, the Apple video chat programme, when an intruder stabbed her in her Texas home.
Her terrified husband, Private Justin Poole, a soldier deployed in south-west Asia, could only look on.
Mrs Rachel Poole, 31, whose baby is due in a week, was rushed to hospital with stab wounds and fractures to her body and face after the attack on Wednesday night, Mail Online reported.
The suspect has been identified as Corey Moss, 19, a soldier at a US army post in Texas.
Doctors said the unborn baby is in good condition. The couple plan to name her Isabella.
According to an arrest affidavit obtained by KFOX14, a TV station in El Paso, Texas, Mrs Poole recognised the suspect as the teen who owed her husband money and screamed out his name.
The police said Mrs Poole was able to call 911 and give Moss' name to them.
Meanwhile, Pte Poole called the 19-year-old's co-workers, who helped to apprehend Moss and seized the knife allegedly used in the attack.
Following Moss' arrest, police said Moss admitted to the stabbing and has been charged with criminal attempted capital murder, Mail Online reported.
The TV station quoted neighbours as saying that he owed the Pooles money for car repairs because he had damaged a vehicle he borrowed from them.
The police said Moss had gone to the Pooles' home to talk to Mrs Poole about the money he owed her husband. She was not home, so he allegedly forced his way into the house and lay in ambush, waiting for her return.
When she got home, she logged on to the programme and began chatting with her husband.
A short time later, police said, Moss came out of hiding and surprised Mrs Poole from behind, repeatedly stabbing her with a foldout stainless steel knife and beating her.
An army spokesman said Pte Poole has been deployed abroad for the past nine months. He was scheduled to arrive home this weekend and is not expected to be sent back to his overseas posting after the attack on his wife.
He took to his Facebook page to express his anger with the situation, writing in part: "I promised to give my life for this freedom not the other way around. I failed her but never again."
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