I'd agree with MrMan. If you want the job, give it your best shot and say nothing.
You mentioned that you are only obliged to give 1 months notice at your current job, but would like to stay 2. All things considered, would it not be better just to give the 1 month and get started in the new job asap so as to minimise any potential issues. Once you're on board and working, they cant discriminate because of your pregnancy. Your danger may be if some medical issue pops up in the meantime which means you are not able to start on the expected date - this would be a grey area legally as you may not be considered an employee until you take up the position.