When Serena Williams gave birth to her daughter, Alexis Olympia Ohanian Jr., via cesarean section in September, her procedure went smoothly. However, the tennis champion subsequently experienced major health complications that almost took her life, reports People.com.

The new mother discussed how her six-day battle with a pulmonary embolism (the sudden blockage of a major blood vessel in the lung) led to multiple surgeries and other medical problems in the latest issue of Vogue.

While she recovered in the hospital, Williams suffered from shortness of breath the day after giving birth to Alexis. Because she had a history of blood clots and wasn’t on her blood thinner medication due to her C-section, Williams knew she was having a pulmonary embolism.

She immediately asked a nurse for a CT scan with contrast and a heparin IV drip. (Heparin is a medicine used to stop blood clots from forming.) The nurse thought Williams was confused and instead doctors performed an ultrasound on her legs.

“I was like, ‘A Doppler?’” said Williams. “‘I need a CT scan and a heparin drip.’”

When the health professionals finally gave Williams a CT scan, several small blood clots appeared to have settled into her lungs. “I was like, ‘Listen to Dr. Williams!’”

But that was only the beginning of Williams’s troubles. Her C-section wound popped open because she underwent intense coughing spells caused by the pulmonary embolism. She endured another surgery during which doctors discovered a large hematoma (blood that collects outside blood vessels) in her abdomen.

Doctors performed a final surgery on Williams to prevent more clots from dislodging and moving into her lungs. She returned home after one week but remained on bed rest for six weeks. She managed with the help of her husband, Alexis Ohanian.

Williams admitted that although motherhood hasn’t been easy, she’s been able to find strength and make it through even stressful postpartum feelings. “Now that I’m 36 and I look at my baby, I remember that this was also one of my goals when I was little, before tennis took over, when I was still kind of a normal girl who played with dolls,” she said.

Click here to learn how racism may place Black mothers at a higher risk of death.