hi not 100% sure but check out what your contracted to and if it says your contracted to only do 5 days then there is nothing you can do, also your employer by law has to consider alternative working hours for you due to pregnancy, get it put in writing to your boss pronto that your pregnant and speak to citizens advice and your doctor about the whole situation. the other thing you need to do is askyour boss for a copy of the pregnancy at work risk assessment that the legally have to carry out as soon as they know your pregnant. i had a nightmare with my previous job and my employer obviously thought i had no idea what the laws were regarding my pregnancy and job! boy did she get a shock! please cover yourself every way you can and even if you dont want to tell everyone your pregnant maybe a select few trustworthy co workers who can be aware of it in case of emergency god forbid. your employer will try every trick in the book to screw you over cos pregnancy at work is inconvenient for them. dont let them!