Fiancée's desperate act to fall pregnant with her dead partner's sperm after he was killed in a crash at Pakenham before they could start a family

A grief-stricken woman whose fiancé was killed in a car accident a week ago has vowed to try and conceive his baby. 

William Van Oosten, 21, was travelling along Toomuc Valley Road in Pakenham, 53km south east of Melbourne's CBD, at 12.40am last Wednesday.

Mr Van Oosten, who was affectionately known as Billy, lost control of his vehicle when it rolled off the side of the road.

Emergency services rushed to the site of the crash and tried to revive Mr Oosten, but he died at the scene. 

The 21-year-old had recently become engaged to his girlfriend-of-four-years, Aroha Skipwith-Taurua, and the pair had made immediate plans to start a family. 

A GoFundMe was created by Mr Van Oosten's close friend Liam Harnett to help Ms Skipwith-Taurua with funeral expenses and the cost of conceiving her finacé's child.  

'[Mr Van Oosten and Ms Skipwith-Taurua] recently got engaged and were going to start a little family of their own,' he wrote. 

'She wants to make Billy's dream come true and give birth to his child.

'Aroha, will need all the support and help she can towards funeral costs, future expenses and continuing on Billy's legacy.'

Mr Harnett's mum, Kylie, said Mr Van Oosten had grown into a 'beautiful young man' who had met the 'love of his life' in Ms Skipwith-Taurua. 

'Once he met her he settled down and started to grow into a decent young man who just had some goals for their future together,' she told news.com.au.

Ms Harnett added she had known Mr Van Oosten since he was four-years-old and he had been best friends with her son Liam. 

The 46-year-old explained Ms Skipwith-Taurua only wants to have Mr Van Oosten's children and hopes to make his dream of having a family come true. 

Ms Skipwith-Taura has already harvested Mr Van Oosten's sperm but is now looking for a place that would help her conceive his child.  

'She will have to go overseas to have this procedure done, so she can conceive Billy's child,' Mrs Harnett said.

'The struggle now is to find somewhere that will do it and obviously it is going to cost her a lot of money, which is why we made the GoFundMe page.' 

'Both their wishes as a couple was to have a child together. Which is why Liam is raising all this money to make sure that happens, in honour of his best mate.'

The Harnetts hope to raise $20,000 for Ms Skipwith-Taurua, which will be used to help cover the procedure, funeral expenses and future costs of raising a child. 

At the time of writing, the GoFundMe had received 24 donations totalling $2,170. 

Mr Van Oosten is survived by his parents William and Sharon, sisters Lara and Tasha, and his fiancée Aroha Skipwith-Taurua. 

A police investigation into the exact circumstances surrounding Mr Van Oosten's crash is ongoing.