Penicillin is one of the safest antibiotics in pregnancy
, provided you are not allergic/ sensitive to it. But being safer doesn't mean you can take it as you wish. try to use them for minimum days as possible. Maintain a good oral hygeine, especially, brush TWICE a day, use warm saline rinses or a good mouthwash. have lesser sticky and sweet food. Now regarding root canals, you can get them done if absolutely necessary, (as deemed necessary by your dentist
) during 2nd trimester (4 to 6 months of pregnancy).