Johnson would not name the hospital, the Post reported.
When Landon was discharged on Feb. 28, he had lost nearly 10 percent of his body weight, according to Castillo-Hegyi's comments on Johnson's blog.
"These are routine and unremarkable findings in newborn babies discharged home to exclusively breastfeed," Castillo-Hegyi wrote.
Less than 12 hours after the family returned home, Landon was unresponsive, Johnson said. He had "gone into cardiac arrest caused by dehydration," she wrote, a claim backed up by Los Angeles County medical examiner's records.
"It was really hard for me to comprehend at that point, because I had been breast-feeding him – 'What do you mean he was dehydrated'" Johnson told the Post. "I couldn't wrap my head around it. I was frustrated with myself because there were these doctors and nurses who kept telling me, 'Just keep feeding him. Just keep him on the breast.'"
Landon died at 19 days old.
Johnson told People magazine that she shared her story so other parents wouldn't have to go through what she went through.
"If you think something is wrong, push on those doctors and nurses as hard as you can to make sure, until you feel that you're being taken care of, that baby's being taken care of," Johnson told People. "Especially at that age, you're the only advocate that baby has so you have to do everything in your power to make sure that baby's taken care of."
She added, "There's nothing wrong with giving your child a bottle," People reported.
But pediatrician and American Academy of Pediatrics representative Andy Bernstein told the Post that cases like Landon's are rare and that most babies can survive on colostrum for days.
"I'm definitely going to encourage breastfeeding when possible," he told the Post, but added that formula is also a "very acceptable source" of nutrition.
Trish MacEnroe, executive director of Baby Friendly USA, also stressed that breastfeeding "is the optimal means for infant nutrition."
"I think it's really important for mothers to know that breastfeeding is safe," she told the Post.
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