According to tech news site CNET, the online retailer has been involved in seven similar legal cases brought by pregnant warehouse workers in the past eight years.

And all of these women allege Amazon failed to accommodate their needs.

In response, Amazon said it had never sacked anyone for being pregnant.

Amazon told BBC News: "It is absolutely not true that Amazon would fire any employee for being pregnant.

"We are an equal opportunity employer.

"We work with our employees to accommodate their medical needs, including pregnancy-related needs.

"We also support new parents by offering various maternity and parental leave benefits."

It did not comment on the cases, most of which were settled out of court.

The latest, brought by Beverly Rosales, who worked at Amazon's Golden State fulfilment centre, is due to be heard in the Superior Court of California in June.

It is not the first time questions have been raised by Amazon warehouse workers charged with preparing and shipping the millions of orders placed online every day.

Amazon has more than 613,000 employees, with 100,000 temporary workers employed over the Christmas period.

'Told I could not be transferred'

The GMB Union, which represents employees from many employment sectors in the UK, told the BBC that it had heard from one woman, who asked to remain anonymous.

It said she told them: "When I found out I was pregnant, I asked my manager to be transferred to a different department.

"I was told I could not be transferred and must continue picking, which involves bending, stretching and moving a heavy cart, and walking miles."

In response, Amazon said it could not comment on "anecdotal" cases and had not been provided with "any evidence that would allow us to investigate".

But it added: "Once an employee informs us they are pregnant we work closely with them and carry out a full risk assessment and, if necessary, consult a doctor.

"If the employee's health or that of the unborn child is at risk due to the work they are employed to do at Amazon, we will vary the employee's conditions to alleviate any risk, or find the employee a suitable, alternative role. We will, as a last option, place the employee on full paid sick leave."

A spokesman for the GMB told the BBC: "We really hoped that Amazon had learnt its lesson from the report we published in 2014. Sadly that does not appear to be the case.

"Pregnant women telling us they are forced to stand for 10 hours. Companies like Amazon should be treating staff with respect, not treating them like robots."