Penny Lancaster found undergoing fertility treatment "heartbreaking and gruelling".
The 44-year-old presenter underwent two unsuccessful rounds of IVF before she and husband Rod Stewart conceived their youngest son Aiden, now four, but she insists the difficult time was all worth it.
Penny - who also has 10-year-old son Alistair with her singer spouse - said: "I tried for two years with IVF, having two unsuccessful rounds, before we had Aiden.
"It was heartbreaking and gruelling emotionally and physically. I wouldn't have the ability to go through that now.
"The other day Aiden said, 'Mummy why do you keep kissing me?' and I said, 'Because it took mummy a long time to make you' and he was like, 'Oh really?'
"I'll explain it to you one day.
"I look at him and think about what it took to produce this little cheeky monkey. It was worth it.' "
Penny would never rule out cosmetic surgery, but doesn't want to change her appearance completely.
She told Woman magazine: "Since I hit 40, I've become more critical of my appearance, but I also remind myself, 'I'm of a certain age and it is really OK to look like this.'
"I'd never say never to plastic surgery and I think my motto is that if you can gently correct something, it's OK.
"The mistake is to change the way you look altogether."