Thanks for asking the query,
As you are pregnant care should be taken before prescription of drugs and during treatment.
Before taking any medication consult your OBGN doctor to know the safety for you.
For dental reasons you can take amoxicillin
Avoid exposure to x-rays.
The infected dentine and pulp can be extirpated and temporary filling can be placed, this will subside the toothache temporarily.
Meantime you maintain a good oral hygiene
at home, use saline water gargles, antiseptic mouthwash like chlorhexidine
Further treatment has to be done after delivary.
Hope this helps out.