Thanks for using the forum.
The feeling of pressure in your abdomen could be the start of contractions. Before you start labor, your body begins to prepare and often women feel Braxton Hicks contractions. At 38 weeks, you know that the start of labor is close. It is important that you pay attention to your body and how you are feeling. If the feeling of pressure, or tightness, comes and goes with no pattern, it is more than likely your body preparing for labor. If the contractions become regular, and start to come closer together that is a sign that your labor may be starting.
Good luck and Congratulations!
Cathy
Sounds like it. Maybe just the beggining though like your body is prepping because contractions hurt so you would know. Plus when I had my first, I lost my mucus plug a few hours after contractions started.