Sophie McBain, who lives in New York, US, felt uncomfortable as she had not pumped that day and needed to do so before her flight.
She asked airport staff where she could get some privacy while pumping milk and was advised to go to the baby changing room.
But she claims a male staff member opened the door on her while she was in the middle of pumping and said she should have left it unlocked or pumped in the main terminal.
“To explain why I was upset I compared it to someone bursting in on you while you are on the toilet and then calmly telling you, while your pants are still round your ankles, that you are hogging the public bathroom,” McBain wrote on Twitter on 22 January.
McBain explained she filed a formal complaint with the airport team as she didn’t want other women to go through the same experience she had.
She hadn’t originally intended to speak out publicly about her experience, but was so unsatisfied with the “excuse-filled, non-apology” she recieved in response.
The mum explained she didn’t want to get anyone in trouble, calling it a “systemic problem”.
“From my perspective what’s really important is that this isn’t about one male attendant’s awkward reaction - he was probably expecting an empty cubicle and we sometimes say weird things when caught off guard,” she told HuffPost UK.
“The reason I am so upset and annoyed is because clearly Heathrow has given no thought to the needs of breastfeeding women and as 1,300 flights land and depart from the airport each day there must be hundreds of us passing through.
“Even when I gave them an opportunity to acknowledge their shortcomings and to suggest ways in which they might prevent this happening again they side-stepped the issue.”
The mum explained her story on a Twitter thread.
McBain explained she told the male staff member that breastfeeding women who are travelling need to pump otherwise they are at risk of serious conditions such as mastitis.
The reply from Heathrow Airport, screenshotted and shared by McBain, explained that a male bathroom attendant will “always enter a bathroom” if he has not had any response from requests to enter.
“In this, while it was uncomfortable it was not entirely his fault for entering after warning,” the reply read.
“With that said, every passenger should be treated with courtesy and respect, meaning we expect our staff to be professional, helpful and polite at all times.
“I appreciate your experience was not acceptable and so I have passed your feedback on to the appropriate terminal’s manager so they can take necessary action.”
Twitter users shared their disgust at how McBain was treated.
A spokesperson for Heathrow Airport told HuffPost UK: “We apologise for Ms McBain’s experience on her recent journey through Heathrow – in our efforts to keep the changing area safe, we fell short in ensuring she had a comfortable experience at our airport.”