Women with hepatitis B can pass on the infection to their child at childbirth.

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

If your job puts you at risk of contracting hepatitis B, you should be immunised against this virus. For example, if you are a healthcare worker, or work at a daycare or residential centre. (Women with hepatitis B can pass on the infection to their child at childbirth.)