Stars have been tweeting over widespread rumours of Simon Cowell becoming a father. US chat show host Jimmy Fallon made fun of Cowell's penchant for tight t-shirts by suggesting he could buy some matching ones for the baby.
His former girlfriend Sinitta joked it was "half miracle, half nightmare."
His fellow Britain's Got Talent judge David Walliams, who became a father earlier this year, quipped "Simon Cowell and I tried to have a baby for many years. But I just couldn't get pregnant."
Cowell's office in Los Angeles declined to comment on the reports.