"God bless Mother Nature #mamaspice," she wrote in the caption alongside a sketch of a heavily pregnant woman.
Later a spokesperson for Geri Horner (nee Halliwell) and her husband Christian Horner, 42, said the couple “are absolutely delighted to announce they are expecting their first child together. The couple is overjoyed with the good news and cannot wait to welcome the newest addition to their family."
Here's her post:
The singer and former Spice Girl’s caption has made the conception sound quite traditional – that is, no IVF or donors.
The chances of getting pregnant at 44 are extremely low – experts say that after 45 it's almost impossible to get pregnant using your own eggs. So while Geri’s seemingly natural conception is not a miracle, it’s rare and not the norm.
Geri married the Red Bull Formula 1 boss (who, by the way, has an OBE) in May last year, where Geri’s daughter Bluebell was a bridesmaid. Both she and Christian have children from previous marriages – Geri has Bluebell, 10, and he has a three-year-old daughter Olivia.
Hello reports that Geri has previously spoken about her wedding day, confessing it was "truly the happiest day" of her life. During an appearance on This Morning, she said: "People talk about their wedding day and until you get there, you don't really know what it's going to be like. It truly was the happiest day of my life, it was so amazing."