The girl believed that, despite being only 14, she could give her child a good life. Details of the entries in her diary were read out in court as the girl, now 15, gave evidence via a video link.
Her alleged attacker, who is now 14, denies rape and two charges of assaulting her on 17 December last year. The case is being heard by St Edmundsbury youth court, sitting at Great Yarmouth.
Ernle Money, for the defence, introduced the diary in cross examination. The entry for Christmas Day last year said: 'I think I'm pregnant. I hope I'm pregnant. I could give a child a good life even though I'm only 14.'
The boy is alleged to have forced her to give him oral sex after she collapsed drunk on a mixture of strong cider and fortified wine. It is also alleged that he had sex with her against her will in a garage at his home in Mildenhall, Suffolk, and then forced her to give him oral sex again.
In another diary entry, the girl wrote that she had been 'totally pissed' and had given the boy oral sex three times and that he had had intercourse with her. The entry ends: 'All I want is to be pregnant to prove what I did.'
Under earlier questioning from Rosamund Horwood-Smart, for the prosecution, she said her mother had been persuaded to buy alcohol from an off-licence. The more she drank the sicker she felt.
She said she had been taunted by the boy throughout the evening. He had pelted her with chips, made her head butt a wall and she had been pushed into a river and burned with cigarettes on the hand and nose.
The girl said they had been drinking strong TNT cider and Thunderbird fortified wine. She had feigned collapses in a bid to stop the persecution.
She said the boy then forced her to have oral sex before taking her into a garage-like building with a concrete floor where he had sexual intercourse with her.
The girl said after another act of oral sex they went into the boy's house and his sister loaned her some shoes. She then went home and straight to bed without telling her mother what had happened.
A few days later the boy met her and threatened to tell her mother she had been using drugs.
The girl finally said she had been raped after attending a school assembly on bullying. The case continues today.