Elton John and David Furnish are expecting their second child together, according to reports.
The couple are believed to be using the same surrogate who gave birth to their son Zachary, who will turn two next month.
According to UK newspaper The Sun, the mother is due to give birth early next year.
"They are over the moon," a source told the publication.
The baby's mother was reportedly recruited via a surrogate parenting facility in Encino, California.
Her identity has not been revealled, although she is said to be "like a sister" to the couple.
A spokesperson for the singer was not available for comment at press time.
Elton, 65, and David, 50, entered into a civil partnership in 2005.
The couple welcomed Zachary on December 25, 2010.
Elton has spoken openly about his desire to give their son a sibling.
"We definitely will have another one. At what stage we don't know, but we definitely will. I don't want him to be an only child," he told the UK's Radio Times in August.