Liz Jacques hadn't been offered a seat on the crowded train, and had to sit down for nearly two hours on the delayed service.
'Is it ok to sit on the floor when you're six months' pregnant and it's standing room only on a delayed commute from TW to London?' she wrote.
Southeastern railway have apologised to Liz for her 'discomfort', and told her that she should consider wearing a baby on board badge to alert other passengers in the future.
Liz, however, argued back that it should have been pretty obvious that she was pregnant, and that Southeastern should work on providing a better service and getting stations reopened.
.@Se_Railway given I'm the size of a small house, I'm not sure that's the issue. Perhaps if you sort out London Bridge & Cannon Street...— Liz Jaques (@lizjaques) August 31, 2016
She spoke to The Huffington Post UK, explaining that the train was unusually busy due to Cannon Street station being closed.
When she boarded the train, the last few seats were taken up too quickly for her to get to them.
'I did try and walk through the carriages, thinking I'd see if there were any seats further up the train (or in first class if I needed to) but it wasn't easy to squeeze through so I gave up after walking through one carriage,' she said.
'I looked around and everyone did that thing where they avoid looking at you, which is understandable in some ways - it's a 50-minute journey and everyone pays a lot of money for their ticket. But still, it's pretty poor form.'
Liz said that although she was clearly pregnant, nobody offered her a seat for the whole journey.
'I sat on the floor by the door. We were delayed by 56 minutes going into London Bridge so it took almost two hours. Even the men around me who were standing sat down towards the end.
'A woman put something in the bin next to me just as we were coming in to London Bridge and said, "Oh, there's a seat available now" - which is pretty annoying.
'It was really uncomfortable - for anyone, let alone a pregnant person.'
Liz has seen tweets and comments saying she didn't need a seat because she isn't 'ill or disabled'.
'I wasn't claiming to be "ill or disabled" at all. It's just that people used to offer seats to people who were more in need then them.
'You're carrying around a lot of extra weight and sometimes you feel pretty shitty.'
Southeastern have responded with the following statement:
'We offer Baby on Board badges to make travelling by train easier for our pregnant passengers. These badges help other passengers spot mums-to-be more easily, helping to prevent women feeling awkward about asking other passengers for a seat. For pregnant women in their second trimester we also provide a free first class upgrade.
We've contacted Ms Jaques to offer her a badge and the free upgrade. We encourage any pregnant passengers or those who require priority seating to get in touch with our customer services team who are on call 24 hours a day.'