It is common for pregnant women to experience a tightening sensation in their stomachs during the 30th week of pregnancy. This sensation, known as Braxton Hicks contractions, is usually harmless and prepares the body for labor. However, if the tightening becomes frequent, intense, or accompanied by other symptoms like pain or bleeding, it could be a sign of preterm labor and should be reported to a healthcare provider immediately. To alleviate discomfort from Braxton Hicks contractions, try changing positions, drinking water, or taking deep breaths.