Erin Peña was waiting to see the doctor because her baby needed an appointment.
People complained that she was breastfeeding her young son without a cover - and she was asked to leave.
A furious Erin posted about the incident on the KCBD Facebook page:
*"I'm so furious and upset. I just got thrown out of my ObyGyn / Pediatrician's office for breastfeeding! The receptionist told me I couldn't breastfeed in the lobby and had to go to the bathroom or room in the back. *
*"I said I had the right to breastfeed anywhere. She said if I don't stop she will cancel my baby's appointment. His appointment was for his vaccines! I refused and she canceled it, so I went to find the doctor thinking she would be reasonable and she wasn't. *
"She was condescending, kept calling me honey. I said, 'No one in the lobby even cared.' She rudely said, yeah they do they just don't say it to your face."
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She added: "I said they were wrong and it was illegal what they were doing. She called security on me and I left with the officer. The guy asked what happened and when I told him, even he was like, What? That's what this was about???
"I'm so disgusted. My doctor even lied saying I was walking around with my breast hanging out, even though she never saw what happened. I was just sitting there in a chair. It was sickening.
"Even though it's against the law, I would respect a restaurant's wishes if it asked me to leave, but a paediatrics's office at UMC??????"
The hospital have since issued an apology, after being reminded that, legally, Erin was absolutely entitled to feed her baby.
As the law in Texas states: "A mother is entitled to breastfeed her baby in any location in which the mother is authorised to be."