Is hardening of the stomach in the 3rd trimester (37 weeks) a sign of labor?

Possibly...or not: Labor pains are felt in the lower abdomen, perineum, lower back, and top of the uterus, aka the fundus. Contraction-like "flexing" of the fundal muscle will feel like a hardening, but is normally transient. If you're starting to feel this call your OB because your cervix has to be checked. Keep track of contraction pace & go to ER stat if you start leaking liquid or blood, or if baby stops moving

Contractions: Could be especially if it is involving the entire uterus