Serena Williams has been an open book since giving birth to her daughter Alexis Olympia in September and in a recent interview with Harper Bazaar UK, the tennis champion talked about how she battled postpartum depression.

“I think people need to talk about it more because it’s almost like the fourth trimester, it’s part of the pregnancy,” she said. “I remember one day, I couldn’t find Olympia’s bottle and I got so upset I started crying… because I wanted to be perfect for her.”

Earlier this year in an op-ed for CNN, Williams said she almost died following the birth of Alexis Olympia.

“It began with a pulmonary embolism, which is a condition in which one or more arteries in the lungs becomes blocked by a blood clot,” Williams wrote for CNN in February. “This sparked a slew of health complications that I am lucky to have survived.”

Despite her bout with postpartum depression, the 23-time Grand Slam champion said she will serve as an inspiration for her daughter.

“I’m going to strive to be the best mom I can be.”