On the day he celebrated his son's first birthday, Daniel Stirling marked a year since his wife's death.

Earlier this year, baby Caleb celebrated his first birthday. For his dad Daniel Stirling, it was a day tinged with sadness, as it also marked the one year anniversary of Sarah’s death.

Sarah Paino was 32 weeks pregnant when she was killed in a car crash in January 2016.

The 24-year-old mother did not survive her injuries. But doctors were able to save her unborn baby, Caleb, through an emergency c-section.

“[It was] Very tough. But we treated it as Caleb’s birthday more so,” Stirling told Channel 7's Sunday Night program.

“I’m doing okay. I have some bad days where I just can’t stop thinking about her, you know. Like every morning the thought’s always there. It’s more so when I’m alone at night.”

Despite his traumatic birth, little Caleb is doing well and has no ongoing health issues.

“He had an appointment last week with the paediatrician at the Royal Hobart Hospital and he absolutely aced it, which made me proud,” Stirling said.

The family suffered enormous tragedy after a 15-year-old male T-boned Sarah's car near the Hobart waterfront last January.

The driver, who was driving a stolen car at the time, was sentenced to five years jail in August 2016. He will have to serve a minimum two and a half years before he is eligible for release.

On now: ‘He’s a little gem, he really is.’ Little Caleb is now 18 months old. #SN7 pic.twitter.com/HJiPWHNxDR

— sunday night (@sundaynighton7) June 25, 2017

Stirling is raising baby Caleb and his older brother Jordan on his own, he says it's a "full on gig" but he wouldn't "change it for the world".

“I think Sarah would be proud,” he said.

“I’ve been told I’m doing good. It’s a very full-on gig but I wouldn’t change it for the world. I’d have Sarah back in a heartbeat, but I’m doing the best I can without her.”