Rod Stewart and his pregnant wife Penny Lancaster have revealed they turned to IVF after a long battle to have another child.
The couple had tried for two years to give their son Alastair a brother or sister but sought medical help after efforts to conceive naturally failed.
Speaking for the first time about their battle, they told this week's Hello! magazine how they tried fertility experts in both America and the UK.
Penny, who posed for pictures with rock star Rod at their LA mansion for the magazine, told how Alastair's joy on hearing he would have a sibling made the struggle worthwhile.
She said: "Our son's happiness made all the IVF treatments worthwhile."
The couple have been on an "emotional rollercoaster" since being told they could not conceive naturally.
And Penny was told mercury levels in her body were "off the scale" as a result of her love of fish, something she believes may have contributed to their problems.
She cut seafood from her diet and after a third IVF cycle their dreams came true.
Recalling the moment she learned of her pregnancy, she told Hello!: "I couldn't believe it. I burst into tears."
"I called Rod when I was still sobbing. Rod said, 'I'm in the middle of a restaurant in Russia, crying'. I kept pinching myself. Neither of us could believe that it had finally happened."