Serena Williams says heart is 'doubled the size' being mom of 2

Serena Williams is celebrating daughter Adira's 1st birthday by getting nostalgic.

Earlier this week, the tennis legend shared a series of images from her maternity photo shoot when she was pregnant with her second child.

"A year ago today - August 15th - I gave birth to my second baby girl, Adira River Ohanian," she wrote in an Instagram post , calling Adira "a true light."

Williams shares both of her daughters -- including Olympia, who was born in September 2017 -- with husband Alexis Ohanian.

The athlete also revealed the meaning behind Adira's name, noting that it is of Hebrew origin and means "mighty," "strong" and "majestic."

"The elegant name is popular in many cultures around the world," she wrote in the caption of a follow-up post. "Adira is the feminine form of the classic name Adir. It is a Biblical name, meaning 'Strong One.'"

In a third Instagram post , Williams opened up about being a mom of two.

"Olympia is always there for me," she wrote of her eldest, saying that at the time, she questioned how she could possibly love anything more than her first daughter.

"Then Adira came along … she is so special, so fun, so funny, so loving, so sweet and so strong!!!" Williams wrote. "You see, God makes your heart get bigger. Because my love for Olympia has not dimmed. My heart simply now is doubled the size and I have a greater capacity to love more!"