Decreased swelling at 3 months, then increased swelling at 4 months! Is this typical?

Thank you for your question. I wouldn't say this is typical per say, but it does happen. As our lymphatic vessels rearrange the swelling in abdomen and trunk can wax and wane. I would recommend deep lymphatic massage by an experiences masseuse. They will essentially massage the lymphatic channels near the lower abdomen and pelvis and help to get the lymphatic fluid back in motion. Best of luck to you!

Thank you for the question and pictures.  What you are experiencing may or may not be "normal". Although some fluctuation of swelling is commonly seen after tummy tuck surgery, you will be best off following up with your plastic surgeon who will be in the best position to rule out problems such as serum (a fluid accumulation between your skin and abdominal wall muscles which may need to be treated). Best wishes.