She confessed to two other housemates, Vanessa and Kemal, that she had something to tell them, but made them promise not to repeat it. The she said: "I could be pregnant."
Makosi, who had previously denied to housemates that she had sex with Anthony and also claimed to be a virgin when the show began, said she does not want Anthony to know.
Kemal asked her what percentage out of 100 she was likely to be pregnant, and the nurse replied: "Ninety if not 100. I'm so stupid."
Anthony also denied to fellow housemates that his clinch in the pool with Makosi had been more than a kiss, and said he was so drunk that he can not remember what happened.
Producers on the Channel 4 programme have refused to comment on whether Makosi has been given a pregnancy test or the morning-after pill, saying that health matters are confidential.
Separately, Science and Maxwell have been nominated by their fellow housemates to face eviction from the show on Friday. Science, who describes himself as an entrepreneur, is the favourite to go, with Ladbrokes giving odds of 1/4 for his eviction, compared with 11/4 for Maxwell.
Ladbrokes spokesman Warren Lush, said: "Punters aren't blinded by Science, it looks like the cockney geezer is going to survive again. If anything support for Maxwell has increased in recent days and he's now one of the favourites to win."
The bookmaker currently has Derek, Maxwell and Makosi as equal favourites to win on odds of 7/2.
The housemates face another week of penury after they failed the holiday camp task, giving them £1 a day to live on each.
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