Certain jobs and workplaces may pose a risk to a pregnancy, in particular to the early stages of pregnancy.

http://www.patient.co.uk/health/planning-to-become-pregnant

Consider your working environment

If you think that your job may pose a risk to a pregnancy then ideally you should discuss this with your employer before becoming pregnant. Certain jobs and workplaces may pose a risk to a pregnancy, in particular to the early stages of pregnancy.