But the issue has led David Cameron's aides to distance himself from sources close to the Coalition's equalities minister, Scottish MP Jo Swinson.
The move was triggered by an incident in the chamber of the male-dominated House of Commons at Prime Minister's Questions.
The seven-months pregnant East Dunbartonshire MP entered Wednesday's session slightly late and was forced to stand at the back.
The sight of Ms Swinson without a place on the famous benches caused political observers to admonish her fellow MPs for failing to offer her a seat.
But sources close to Ms Swinson, 33, denounced such an attitude as "sexist".
They insisted that being pregnant did not preclude the Liberal Democrat business minister from being able to stand "for 15 minutes" and that to think otherwise was patronising towards women.
Downing Street yesterday took a rather different view.
No 10 insisted it was the "decent" thing to offer a pregnant woman a seat and rejected the suggestion such a move could be sexist.
The Prime Minister's spokesman said: "If you see someone who's in greater need of a seat then offering that seat is a good thing ... a decent thing to do."
This included members of parliament, he added.
He said: "In every walk of life, if you see somebody who is in greater need than yourself, then offering a seat...that's a very understandable thing to do."
The spokesman said if Mr Cameron were to meet a pregnant lady on a bus he would stand up to offer her his seat.
He said it would be right to give up a seat to other groups including the elderly and those travelling with "lots of children".
As the furore mounted, Ms Swinson last night attempted to calm the row in a tweet.
She said she was "happier standing" at PMQs but would welcome the offer of a seat on the London Underground.
She joked: "About to get on the Tube - seat offers welcome and definitely not sexist. But I was happier standing at PMQs yesterday."
Ms Swinson and her husband, fellow LibDem MP Duncan Hames, have been given a due date for their first child of Christmas Day.
Interviewed in June, the couple described their excitement at the news. She said Mr Hames was proudly showing everyone the images of her scans.
Ms Swinson, speaking when the child was 13 weeks, said: "The due date is actually Christmas Day.
"It's said you very rarely actually give birth on the due date, but we have already been told by friends that we'll need to make sure that there are separate presents and maybe a different 'official' birthday."
Ms Swinson was herself affectionately known as the 'baby of the house' of Commons between 2005 and 2009 as she was the youngest MP.
She has spoken about her passion for her ministerial job but insists she will not be working while on maternity leave.
Earlier this month she said: "I am still very committed and enjoy my job and want to come back to continue doing that, but I think having a bit of time to do that early bonding is also really important.
"Duncan and I have obviously discussed wanting to share the parenting as much as possible.
"Like most new parents, we are both very excited about our new arrival and wanting to be very hands-on from the start."
An advocate of flexible parental leave after the birth of a baby, she is working to bring in rules that would allow new parents to divide up time away from work however they see fit.