Madonna is trying for a baby with her toyboy lover Jesus Luz.
The Queen of Pop - who already has four kids - has consulted doctors about conceiving another child at the age of 51, pals said.
Brazilian Jesus, who at 22 is less than half Madge's age, has told her that becoming a father would be "his greatest adventure".
She is said to have agreed he would make a "fantastic dad" and told friends: "I have endless love in my heart for another child."
Madge already has daughter Lourdes, 13, by Carlos Leon and son Rocco, nine, by ex-husband Guy Ritchie.
She is also mum to her adopted Malawian orphans David Banda and Mercy James, both four.
A close pal, who calls Madonna by her preferred nickname Em, said: "Em says motherhood is her greatest achievement and the most fulfilling thing in her life.
"She knows that, at 51, it's going to be harder to conceive naturally. But she is Olympic-athlete fit and is ready for the challenge."
Madge has been with Jesus for more than two years, meeting him during a photo-shoot in Brazil shortly after she divorced Sherlock Holmes movie director Guy, 41. The pal added: "Jesus is very religious and deeply in love with her.
"He adores her kids but has always wanted a child of his own.
"He told Em fatherhood would be his greatest adventure, and that he wanted to go on this journey with her."
The superstar has often talked of her love of motherhood. She has said "all the money in the world" would not bring her the happiness of a family.