Did anyone reduce their working hours during their first trimester?

Did anyone reduce their working hours during their first trimester? Im a nurse and my work is very heavy, moving and handling, long shifts and long periods on feet. To top it off its been so busy recently I've been getting chest pains towards the end of the shift.

Although it's our legal right to reduce hours, there is no mention of this own the trust policy. Wondering if anyone has been in my position? Will it affect my maternity leave?