Nazanin Zaghari-Ratcliffe is due to begin a hunger strike over her treatment in prison in Iran.
The British-Iranian detainee is planning to protest for at least three days from Monday, alongside human rights activist Narges Mohammadi, who has been charged several times for criticising the Iranian government.
Both are unhappy about being denied access to a doctor and medication at the jail in the capital Tehran.
In a joint letter published earlier this month, the pair said: “We are urging for an immediate action to be taken.”
Mrs Zaghari-Ratcliffe’s husband, Richard Ratcliffe, has previously revealed that she has suffered several panic attacks in jail, which left her with numbness in her legs and headaches.
Last week, following the release of footage of the moment the mother-of-one was arrested in April 2016, Mr Ratcliffe said her rations had been cut and his phone calls reduced in duration since the strike was announced.
The video, which was broadcast on Iranian state TV, showed the 40-year-old pushing a baggage cart along at Imam Khomeini International Airport in Tehran before handing her passport over to an unidentified man.
Mrs Zaghari-Ratcliffe, from Hampstead, north London, is later told by a representative of the public prosecutor that a warrant has been issued for her arrest and that she is barred from leaving the country.
She was eventually charged over claims that she was “plotting to overthrow the Iranian regime”, having been in Iran to visit her family for Nowruz, the Persian New Year festival, with her young daughter.
Press TV, the state-owned and controlled English and French language Iranian news channel, claimed she was involved in “plans for regime change in Iran”.
She was convicted last year, despite her denials.
Mr Ratcliffe told Sky News he feared the whole period of his wife’s incarceration was being filmed, and that the Iranian authorities could “drip feed this out whenever they want to, just as a cruel psychological game”.
He said he believed the footage had been released as a direct response to the hunger strike, which is set to last for three days but could go on for longer.
Mrs Zaghari-Ratcliffe saw the video in prison, he added, bringing the “violation” of her arrest back to her