The parents of baby Riley Hughes, who died from whooping cough at four weeks old, have welcomed their third child, a daughter, into the world.
Vaccination advocates Catherine and Greg Hughes posted on their Light for Riley Facebook page on Saturday that they was delighted at the arrival of their "precious rainbow baby".
"Both mum and bubs are doing very well considering the emotional challenges faced after the loss of our brave boy," Mr Hughes said.
"Her big sister is ecstatic to have her here and has already begun bossing dad around about handling baby every opportunity she gets (surprisingly she isn't willing to take the lead on nappy changes!).
"We'd like to thank our incredible community of supporters for all their beautiful words of kindness.
"We can't wait for you all to meet her properly and we're looking forward to this new chapter in our lives."
The couple had previously said they were excited but nervous about the pending addition to their family.
"We are overjoyed but very nervous at the same time. We haven't allowed ourselves to get too excited until our scan this morning as the scars of losing Riley run deeply," Ms Hughes said in February.
Ms Hughes ensured she had the whooping cough vaccination booster during her third trimester - an immunisation she had fought for as part of Riley's legacy.
The free booster shot provides the best defence against whooping cough in newborns and was rolled out in Australia as a direct result of Riley's death.
Ms Hughes, who was awarded WA's Young Australian of the Year in 2016, also raised $70,000 for whooping cough research and instigated a viral campaign for the donation of more than 45,000 vaccines to UNICEF.
Riley died in March 2015 at four weeks old after contracting the preventable disease. At the time, he was too young to be immunised.
In a post written on Facebook following his death, his mother said she wanted to be a driver of change to protect others against whooping cough.
"We're desperate to ensure the passing of our child has not been in vain and to try and assist other families who may be potentially suffering from similar circumstances," Ms Hughes said.
"Long term we'd ideally like to be the drivers of change within this country surrounding the treatment, management and long term eradication of this horrific disease."