Alex Jones hosted The One Show just an hour after learning she'd suffered a miscarriage.
The 42-year-old star - who has son Teddy, two, with husband Charlie Thomson and is currently seven months pregnant - learned she was pregnant while in New Zealand over the festive period on 2017.
But a few weeks later, she underwent a private ultrasound scan in the UK and was given the devastating news that the baby had "stopped developing".
She recalled: "We learnt the baby didn't have a heartbeat. I was around 14 weeks, which is a decent amount of time.
"The baby had stopped developing at about nine weeks. That was really hard. It hit us like a ton of bricks.
"It's really odd. You're in that room looking for answers that you're never going to get.
"You're thinking, Have I done something wrong? What did I do differently? Was it because we flew a long way?
You're thinking: 'Have I done something wrong? What did I do differently?'
"Was I too stressed? Was I putting too much pressure on myself?' "
Alex confided in her boss, who told her to take time off but she insisted on going back on air that evening.
She told the Sunday Telegraph's Stella magazine: "I said, 'What else am I going to do?' It's a horrible feeling because it is so empty. There's nothing to say. It's done.' "
Read more: Alex Jones' maternity cover revealed
Six months after her miscarriage, the Welsh presenter fell pregnant again but she admitted she "couldn't enjoy" it for a long time and hasn't been able to "relax" in case something goes wrong again.
She admitted: "It was completely different. You don't let yourself relax.
"I couldn't enjoy it for a long time and didn't tell anyone for ages."
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