Your general risk assessment must already cover risks to new or expectant mothers where the work could harm them or their baby. Use it as the starting point, and involve her: she may have advice from her midwife or GP. Look at manual handling, long periods standing or sitting, chemical and biological agents, radiation, night work and long hours, stress, temperature and rest facilities.
Protect new and expectant mothers at work
Risk factors, the action you must take and night work.