London Underground is to give special badges to pregnant women in a trial to try to encourage people to give up their seats to mums-to-be.
The badges will bear the slogan 'Baby on Board', more often seen on car windows, and would make pregnant women more identifiable to fellow passengers.
Research by London Underground found most mums-to-be never asked for a seat on full tube trains even, though most travellers believed they should be offered a seat.
A spokeswoman for London Underground said: 'It is sad but true that passengers who need to sit down feel that they cannot ask fellow passengers for a seat.'
If the trial proves popular, badges will be offered to all pregnant Tube users.