One mother, Dr Jennifer Gunter, replied to Sanders' tweet saying she was billed US$600 when her newborn son died shortly after she gave birth.
"$600 for my son who lived about 3 minutes," Gunter tweeted. "He received no medical care. At all. As he died almost immediately he didn't get enrolled in my insurance plan, so I got the bill. From the hospital where I was a doctor.
Gunter went on: "It was from my own department too. Ha! You asked for absurd. When I got home this $600 bill came for Aidan. It was addressed to 'Parent of Aidan XXX' ...and for a second I thought his death was a dream and I got very hopeful he was alive and then confused.
"And then I called the billing department and literally had to argue with them about my son being dead and they didn't believe me that I let him die without medical care. I am literally explaining how some babies are born to die. They say, 'Too bad'.
"So I wrote a very threatening e-mail to the hospital CEO and told him I would call the newspaper (this was pre Twitter) and tell everyone how my own hospital tried to bill me for care my dead baby never received.
"And that is how I became a patient advocate.
"I'd forgotten about those few seconds that felt like an eternity when I saw the letter addressed to 'Parents of Aidan...'
"I was really confused. I had sepsis and was just home maybe 3 days. My other two were in the NICU. I really thought for a moment he was alive. Sigh."
Another mother, Heather Brodzenski, responded to Sanders' tweet with her own story.
Brodzenski, a nurse, said she was charged US$218,000 after an emergency C-section and two surgeries on her newborn daughter who died 12 days later.
Despite having insurance she says she had to pay US$30,000 in medical bills.
Others told similar stories or posted images of being billed thousands of dollars after health issues.
Amy Sterling Casil tweeted: "$20,000 after my baby Anthony died at Tarzana Medical Center which was 15 minutes farther than the hospital where he was born where we were insured (Kaiser). He choked on his formula and was unconscious then died."
Another wrote: "The bill for the loss of our pregnancy at 17 1/2 weeks. paid all but 2000, the ambulance was an addl $1600. So, on top of the emotional toll it cost me $3600.I still owe them most of that money. Every bill and call is a reminder of losing my baby girl."