Feb. 20 (UPI) -- Tennis star Serena Williams says she "almost died" while giving birth to daughter Alexis Olympia Ohanian.
Williams and husband Alexis Ohanian welcomed the newborn on Sept. 1. Alexis Olympia was delivered via emergency C-section, after her heart rate dropped dramatically.
"I almost died after giving birth to my daughter, Olympia," Williams wrote. "Yet I consider myself fortunate."
"While I had a pretty easy pregnancy, my daughter was born by emergency C-section after her heart rate dropped dramatically during contractions. The surgery went smoothly. Before I knew it, Olympia was in my arms. It was the most amazing feeling I've ever experienced in my life. But what followed just 24 hours after giving birth were six days of uncertainty."
Williams' traumatic sequence began with a pulmonary embolism -- a condition when arteries in the lungs become blocked by a blood clot. Later, her C-section wound popped open due to intense coughing. When she returned to surgery, doctors found a large hematoma in her abdomen. Williams spent the first six weeks of motherhood in her bed.
Williams -- who also works as a UNICEF goodwill ambassador -- called for people to "donate to UNICEF and other organizations around the world working to make a different for mothers and babies in need."
The tennis sensation hasn't played in a Grand Slam tournament since winning the 2017 Australian Open. Olympia attended her mom's match on Feb. 11 at the 2018 Fed Cup in Asheville, N.C.
Serena and Venus Williams lost 6-2, 6-3 to Lesley Kerkhove and Demi Schuurs in a doubles match.