BB had paired housemates together to look after a fake baby, but when Kate broke down in tears and wanted to leave the house, it was clear there had been an unexpected and emotional trigger.
Kate explained to BB and later to her housemates that she had lost a baby through pre-eclampsia.
The incident was first leaked at Behind Big Brother Australia, which pointed to vanishing websites on the official TEN site.
It has since been detailed in full at bigbrother.com.au and in the daily show.
The baby-care task was also used in the first season of BB.
Kate is up for eviction this week and this turn of events may have a significant sympathy push, which would be a pure turn of fate.
Meanwhile the bigger question is how did this happen? Either housemates have not confided enough prior to entering the house, or BB needs better research.