Her account comes after a report from the Anti-Trafficking Monitoring Group said pregnant women were "systematically overlooked" in the UK's trafficking response.
Marta, not her real name, told the Victoria Derbyshire programme that she came to Birmingham in November 2014 thinking she would get a job in a poultry factory, where a number of her friends were working.
"But my boyfriend and I had our passports taken and we were put to work on a dump," she explained.
"They took our documents and our bank cards and they took our wages. We were being moved from site to site. We were given old stale food that was obviously very cheap."
Marta and her partner do not speak English so they struggled to get help. She claims it was during this time she realised that she was pregnant.
"If you didn't follow and obey their orders you were not given any food," she said.
"The worst time was when I was five months pregnant, we were so hungry that we had to eat from rubbish bins.
"We found a sandwich factory who were throwing out old sandwiches so we mainly survived on them."
Marta claims when she told the gang she was pregnant they reduced the amount of work they sent her out to do.
"Even though I was pregnant I was losing a lot of weight," she said.
"I wasn't feeling well and they gave me my phone. I was able to get wi-fi and texted my friends in Ireland telling them where I was working.
"They went to the police and the police found us three days later."
Marta was rescued in April 2015 and taken to a safe house in Manchester where volunteers got her medical help and took her to see a midwife. She was told she was malnourished and that the baby was not feeding properly in the womb.
She was also interviewed by police and claims the translator told her that the reason the gang had stopped her working is that they probably had plans to sell her baby.
"I was really worried when I heard they might have sold my baby," she said.
"There was another pregnant woman there and when her baby was born we never saw her again."
After leaving the safe house Marta returned to Poland. Her son is now six months old and his health is beginning to improve.
No charges have been brought in relation to her case.
In a statement, Home Office Minister Karen Bradley said:"We are currently working with a broad range of interested parties on how best to support trafficked children and intend to announce proposals before Easter."
The Victoria Derbyshire programme is broadcast on weekdays between 09:15 and 11:00 on BBC Two and the BBC News channel.
A young Polish woman has described how she was forced to eat rubbish from bins while she was pregnant after being trafficked to the UK.