There is no efficacy or safety data because the vaccine hasn't been trialled on pregnant women.
However, we do know that antibodies that the mother makes in response to the whooping cough vaccine cross the placenta and it is thought that this would confer protection on the baby, as this is how it works with other antibodies.
The Repevax vaccine is the one being given because babies are dying and it is the only whopping cough vaccine available right now in the UK in sufficient quantities to vaccinate pregnant women as well as the children scheduled to have it.
3 of the 4 vaccines contained in Repevax have been given to pregnant women in the US for over a year. Polio hasn't been administered on a wide scale however it has been given to pregnant women who have needed it (e.g. for travel) without problems.
None of the vaccines in Repevax are live, they don't contain live polio, whooping cough etc. From what we know about how dead vaccines work, it just doesn't make any sense that they could harm an unborn baby, and no dead vaccine has been shown to cause any problems in pregnant women.
I had the vaccine.