Hello student to be honest no in medical college placement didn't get affected by class 12th percentage because you've enough time to showcase your skills during your course duration of 5years so focus on your course and try to score good in every semester otherwise don't worry. And it's already difficult to get into medical college so if you're into a medical college you should appreciate that and look forward to Learn and score well in upcoming exams.

Feel free to comment if you've any doubt

Good luck