What are the best sex positions in the third trimester?

Most comfortable. Often this is some variation of a side by side. These are more comfortable for the mom-to-be and have shallower penetration which puts less pressure on the cervix. Sometimes, depending on the patient and the pregnancy, it can be a challenge to find a comfortable position.
3RD TRI. Likely male behind once the abdomen is protruding beyond the pubis.