The mum-to-be's contractions were six minutes apart and she was about to leave for hospital when the men burst in and attacked her with crowbars and baseball bats and slashed her face with a knife.
She suffered a haemorrhage and may have a fractured skull.
Her 32-year-old partner was upstairs collecting the hospital bag and their two-year-old son was asleep in bed when the gang struck.
The appalling attack happened in Basildon, Essex, at around 8.30pm on Monday night (March 2).
The mother-of-two, who has not been identified, was rushed to Basildon Hospital and gave birth to a healthy baby on Tuesday, despite her injuries.
Her partner said: "Her contractions were about six minutes apart, so I went upstairs to get her hospital bag and to phone the babysitter to come and look after our two-year-old.
"The next thing I heard a loud smash - like a fish tank shattering.
"Before we knew it we had five men in the house screaming 'give us your money'. They cornered my partner then hit her with a crowbar and bats and cut her across the face screaming and demanding more money.
"I just threw my arms round her to protect her. They carried on beating us. I was just shouting back at them, 'you are wrong, man, she is in labour.
"Me and my girlfriend just started screaming and shouting for help."
The men grabbed the couple's iPad, a Sony Experia mobile phone and £60 in cash and then ran off.
Police are now hunting the five men, all aged in their twenties with local accents.
Three of the men wore balaclavas and dark clothes, a fourth gang member was white and the fifth was mixed race.
The woman's partner said: "I can't even describe to you how angry I am. My partner is too traumatised to even go back to our home. She is going to need counselling to help her get through this. To do this to a woman who is in labour - it's sick."
Detective Inspector Joel Henderson, from Basildon CID, said: "This was a shocking attack on a young woman who was in labour. It is vital we get those people responsible off the streets of Basildon."
Anyone with information can call Basildon CID on 101.