The couple have been honest about their struggles to fall pregnant this year, even detailing their anguish in a podcast, called What The IVF.
Back in August, Fiona revealed she and Hayley had been trying for months to fall pregnant, a journey she described as a "traumatic" and "lonely" one.
"Obviously you have your partner but it can actually feel like a really lonely process," Fiona told The Daily Telegraph at the time.
"It is you and your body against all odds. Women don't really talk about it until after the fact. It can be really quite traumatic."
Hayley, who proposed to Fiona in April 2019 after a whirlwind eight-month romance, explained the pair both want to carry a child at some stage.
"Fi is going first because she is older. I really want to carry a bub too but Fi will go first just because of the body clock on fertility, so her going first is best," Hayley told the publication.
"I will give it a crack after we have our first child," the sports reporter added.
Fiona added that the couple want to "have the babies quite close to each other", joking that they will "lose all the sleep at once".
The couple have been together for about two years and first met after Hayley messaged Fiona on Instagram, with the pair later meeting up in real life for a drink.
Fiona "came out" publicly for the first time in 2017, when she revealed she was dating personal trainer Lara Creber.
Lara was Fiona's first same-sex relationship. The pair split around April 2018 after dating for a few months.