Hailey Bieber Feared Death After 18-Hour Labor, 'Scary' Postpartum Hemorrhage

Hailey Bieber is opening up about childbirth like never before -- just under a year after giving birth to her and Justin Bieber's first child ... revealing death crossed her mind as she dealt with serious postpartum complications.

The Rhode Beauty founder candidly discussed her unmedicated birth while speaking to Vogue for the mag's summer cover story -- revealing she experienced a "scary" postpartum hemorrhage that made her weigh the possibility of death.

She explains that although she trusted her doctor with her life, she was "bleeding really badly" after her 18-hour labor, adding ... "And people die, and the thought crosses your mind."

Hailey recalls after welcoming her little one, she wanted nothing more than to hold him in her arms ... but doctors were rushing to stop the bleeding, working on possible solutions for hours before she was cleared.

The model and businesswoman says giving birth to Jack Blues is the "hardest thing" she's ever done -- despite preparing herself throughout her whole pregnancy with yoga, pelvic-floor therapy, various exercises, weight training, breathing exercises and even acupuncture.

She notes ... "I was doing everything. I felt stronger physically than I ever had before."

Though her birth didn't go as planned -- she had hoped to go into labor naturally, but she began leaking amniotic fluid at 39 weeks and was induced -- she says it all worked out. She happily explains ... "I’m walking in the days I always dreamed of."

And her bumpy labor didn't scare her off from having more kids -- she's hoping for at least one more, but says she will see how life progresses.