"Then everything went bad." Serena Williams shares her terrifying birth story.

Tennis champion Serena Williams says giving birth to her daughter in September was “an amazing feeling” but also extraordinarily frightening.

Speaking to Vogue, the 36-year-old said she endured an emergency c-section after the baby’s heart rate dropped, blood clots in her lungs and hemorrhaging in her abdomen.

Williams went into labour on September 1 last year but, during contractions, her baby’s heart rate plunged to dangerous levels. The tennis star was rushed into surgery for an emergency caesarean, which – like the pregnancy – went utterly smoothly.

Her now-husband, Reddit co-founder Alexis Ohanian, cut the cord and laid little Alexis Olympia on Williams’ chest. “It was an amazing feeling,” Williams told Vogue. “And then everything went bad.”

Having suffered with blood clots her whole life, Williams knew the dangers when she began feeling short of breath the day after giving birth. She hadn’t been taking her usual anti-coagulant medication following the surgery, and she thought she might be suffering a pulmonary embolism (blood clots in the lungs).

Careful not to alarm her mother, Williams left her room to ask the nurse for a CT scan and IV heparin (a blood thinner).

A post shared by Serena Williams (@serenawilliams) on Jan 10, 2018 at 5:05am PST

The doctors sent her for an ultrasound instead, which didn’t show anything. “I was like, a Doppler? I told you, I need a CT scan and a heparin drip,” Williams said.

Finally, after a CT scan did show multiple blood clots in her lungs, Williams was given the blood-thinning medication she knew she needed. “I was like, listen to Dr Williams!” she recalled.

Pulmonary embolisms can be fatal, and each year in Australia there are up to 400 deaths from the condition, according to the government’s Department of Health.

Most people associate blood clotting in the lungs with travel on an airplane causing deep-vein thrombosis. The majority of deaths, however, are due to other risk factors. One of these risk factors is pregnancy.

A post shared by Serena Williams (@serenawilliams) on Nov 6, 2017 at 5:09am PST

Still, for Williams the ordeal wasn’t over. Because the clots in her lungs had caused severe coughing, and also on account of the blood-thinning medication she was given as treatment, the wound from Williams’ caesarean popped and flooded her abdomen with blood.

Into the operating room once more she went, and doctors inserted a filter into a major vein to clear the blood and prevent more clots from travelling to her lungs.

For the first six weeks of her pregnancy, Williams was unable to get out of bed. “Consider for a moment that your body is one of the greatest things on this planet, and you’re trapped in it,” Ohanian told Vogue.

She and her baby narrowly escaped disaster, death even, during the days of Alexis’ birth. At times, Williams said she “got really down” and thought “Man, I can’t do this”. Even still, she has bouts of negativity where she cannot deal with the emotional upheaval that is looking after a newborn baby.

“I’ll get angry about the crying, then sad about being angry, and then guilty, like, ‘Why do I feel so sad when I have a beautiful baby?’,” she said.

LISTEN: Apparently, Serene Williams isn’t a baby person. Her words, not ours. Post continues after audio. 

It’s not all bad news, however, and the 36-year-old tennis champion deeply believes her new-found motherhood will help her competitively, too. Williams says she “absolutely” intends to beat the current women’s record of 24 grand slam titles in a career; she’s currently holding 23.

“Maybe this goes without saying, but it needs to be said in a powerful way: I absolutely want more grand slams. It’s not a secret that I have my sights on 25, and actually, I think having a baby might help,” Williams told the magazine.

“When I’m too anxious I lose matches, and I feel like a lot of that anxiety disappeared when Olympia was born.

“Knowing I’ve got this beautiful baby to go home to makes me feel like I don’t have to play another match. I don’t need the money or the titles or the prestige. I want them, but I don’t need them. That’s a different feeling for me.”

This comes after Williams decided to pull out of the Australian Open saying she’s “not where she personally wants to be”. She won the Open last year when she defeated her sister Venus in the final. Later it would emerge she was in the early stages of pregnancy while competing.

In celebration of @SerenaWilliams‘s power and unwavering confidence, a look back at how the tennis champion lives by her own beauty standards: https://t.co/YWPK3ezlJ3 pic.twitter.com/OyGSLKjNWa

— Vogue Magazine (@voguemagazine) January 10, 2018

She and Alexis Olympia graced the cover of Vogue’s February edition alongside the interview.

“When I first saw this cover it brought tears to my eyes,” Williams posted to Instagram alongside a picture of the magazine. “All Vogue covers are special but to share this one with my beautiful daughter makes it moment I will never forget.”

At just four months old, Alexis Olympia is the youngest star ever to be featured on the cover of Vogue US and she unequivocally stole the show.

What can you say? Tears and all, she’s a natural.