The heavily pregnant Labour MP for Hampstead and Kilburn was wheeled into the chamber ahead of the first vote on Tuesday night, on an amendment brought by Tory MP John Baron, the Evening Standard reported.
The 36-year-old was seen in the chamber chatting to other MPs, according to the report.
Usually, heavily pregnant MPs, those with newborns and the sick are able to be “paired” with an opposition party member who also cannot vote so the overall result is not affected.
But after Conservative Party chairman Brandon Lewis broke a pairing arrangement with Liberal Democrat Deputy Leader Jo Swinson in July 2018, Tulip said she could no longer trust the system.
In a Twitter post earlier on Tuesday, Tulip thanked people for support after her decision was first reported by the Evening Standard.
"My decision to delay my baby's birth is not one I take lightly. Let me be clear, I have no faith in the pairing system, in July the Govt stole the vote of a new mother. It's my duty to represent Hampstead & Kilburn, and I will do just that," she wrote.
She told the Standard earlier this week: “If my son enters the world even one day later than the doctors advised, but it’s a world with a better chance of a strong relationship between Britain and Europe, then that’s worth fighting for.”
Parliament voted 432-202 against May’s deal, the worst parliamentary defeat for a government in British history.
Opposition Labour leader Jeremy Corbyn promptly called a vote of no confidence in May's government, which will be held within 24 hours.
Bangladeshi-origin Tulip is the daughter of Prime Minister Sheikh Hasina’s sister Sheikh Rehana.
