Hi..
Can understand your concern..
As per your complain swelling in gums is seen in a large number of women who are pregnant due to 
hormonal changes.
But in case if you have swelling in gum and jaw on any one side and it is due to any infected tooth then it is a different case..
In case if it is due to infected or decayed tooth then you will have to wait till you deliver the baby as any x ray,dental treatment and local anaesthesia is not indicated in 
pregnancy..
You can take medicines to reduce infection and pain..
Although it is not advisable to take medicines during the first trimester of pregnancy and the second trimester is found safest to undergo any minor dental procedure like scaling or to take medicines indicated safe during pregnancy..
The commonly given antibiotics during pregnancy are Penicillin group like 
amoxicillin, 
ampicillin. Few others like 
clindamycin is found safe but penicillin group is commonly advised..
For pain 
Acetaminophen available under different names like CALPOL,TYLENOL etc is commonly advised...
In case it is only swelling of the gums due to pregnancy and not associated with any tooth then brushing twice daily, flossing, antimicrobial mouthwash especially alcohol free mouthwash can be helpful..
In case the dentist finds some deposits on teeth like plaque and calculus which can further cause infection and increase inflammation and swelling he can do scaling to clean the teeth preferably in second trimester of pregnancy..
As the pregnancy induced gum swelling mostly subsides after the termination of pregnancy once the baby is delivered.
You should 
consult a dentist before you proceed to take any medicine .
A dentist can very well decide that what exactly causing you the discomfort and treat you accordingly..
Hope your query is solved..
Thanks and regard..
Dr.Honey Nandwani Arora.