Bianca Fazey had been told that it was unlikely she would become a mother without fertility treatments, so when she fell pregnant naturally she was shocked.
Not only was the baby a complete surprise, there was a catch: the baby's father was a man she'd had a one night stand with, and she didn't know how to contact him to let him know.
Bianca, 24, who suffers from polycystic ovarian syndrome, knew that the man's name was Jeremy and that he lived in Morley, Perth. For five months she tried to find the mysterious man, but was unable to track him down.
"I was at my wits' end," she told Daily Mail Australia. "I tried finding him for months and felt pressured by a friend who was adamant I don't give up despite exhausting all avenues."
Desperate, Bianca eventually posted an ad on Gumtree. It starts: "Looking for Jeremy from Morley ... I have something that belongs to him."
"I met a guy named Jeremy on the 23rd of April at Harlem Wednesdays. We ended up spending the night together and I ended up pregnant," she wrote.
It details what she knows about him – he was staying at Rydges hotel (which can't give her any information due to privacy laws), he lives with a group of guys and had just returned from a four-week-on, one-week- off FIFO job. She also knows his mum calls him Jeremiah.
"He was handsome, about 5'7ish, in his 20s, brown hair, brown eyes, no tattoo's (sic), very friendly and lovely gentleman."
She also included a photo of herself, "just in case he was as intoxicated as [she] was".
While Bianca expected to be called a few names over her choices, she soon had to pull the ad down due to judgmental and abusive messages.
"It was sad to see people saying I should get an abortion, those were the only comments that hurt," she told the Daily Mail.
"Society is still hating on women who choose to keep pregnancy outside of a relationship. I was more mad at the amount of women, mums included, saying I shouldn't go through with it."
"All I can say is I chose to go ahead with the pregnancy because I didn't think I could have children … I didn't want to give up my chance, and I'm so grateful I didn't."
She was also disappointed by the vitriol aimed at her when no negativity was directed at Jeremy
Now, Bianca is looking forward to meeting her son. She says she has the support of her family and friends, and despite the unusual start to her baby's life, she hopes his dad comes forward eventually.
"I do hope that I can find him and let him know, he can make his own choice [if he wants to be involved]," she said.
"But more for the sake of the kid, when he asks questions or wants to find him, I want to be prepared."