Mike and Zara's middle child is Lena Elizabeth Tindall and her middle name pays homage to the Queen.
WATCH: Mike Tindall reveals the birth of his baby boy on his podcast
Meanwhile, the couple have called their newborn son Lucas Philip Tindall in tribute to the Duke of Edinburgh, who turns 100 in June.
And rather sweetly, Princess Anne gave her daughter the full name of Zara Anne Elizabeth Phillips when she was born in 1981.
Shortly after Mike and Zara confirmed their happy news on Wednesday, Buckingham Palace released a short but sweet statement which read: "The Queen and The Duke of Edinburgh are delighted with the news and look forward to meeting their 10th Great Grandchild when circumstances allow."
Baby Lucas is 22nd in line to the throne behind his older sister Lena.
Mike and Zara's middle child is Lena Elizabeth Tindall
Zara isn't the only one of the Queen's grandchildren to honour the monarch and her husband with her children's middle names.
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