It's not uncommon to feel tightness in your abdomen during pregnancy. In many cases, tightness that comes and goes is caused by your uterus contracting or the fetus moving. Your expanding baby bump can also cause a persistent feeling of tightness, especially in the last few months of pregnancy. Most abdominal tightening during pregnancy is harmless, but preterm labor and potentially serious pregnancy complications can also cause your abdomen to feel tight. Call your doctor if you have any concerns about abdominal tightening.
Braxton Hicks Contractions
Your uterus has a strong muscular wall that contracts frequently, even when you are not pregnant. During labor, the uterus initiates rhythmic muscle contractions that gradually thin and dilate the cervix -- the opening between your womb and vagina. Your uterine muscle tissue gets stronger through exercise. Braxton Hicks contractions help strengthen the lower region of your uterus and may help to increase blood flow to the placenta, which ensures that your baby gets the nutrients he needs. You may feel Braxton Hicks contractions, which start as early as the sixth week, at any time during pregnancy. In the last month of pregnancy, you may experience more frequent and intense Braxton Hicks contractions.
Braxton Hicks Contractions Versus Labor
It is not always easy to tell the difference between Braxton Hicks contractions and labor, but several features can help you distinguish the two. Unlike true labor, Braxton Hicks contractions usually do not cause pain, especially in the first and second trimesters. If you experience discomfort with Braxton Hicks contractions, the pain rarely moves to your back, unlike true labor contractions. Braxton Hicks contractions also do not fall into a regular pattern. Even more telling, you can often stop Braxton Hicks contractions by changing position, walking around or eating. Real labor contractions do not stop when you do any of these things.
According to the text "Blueprints Obstetrics and Gynecology," the placenta, which nourishes your baby, prematurely detaches from the uterine wall in 0.5 to 1.5 percent of pregnancies. Significant bleeding can occur when the placenta detaches, potentially causing your uterus to become very firm and often tender to the touch. The tightening does not come and go but persists, and your abdomen may get progressively firmer. This complication, called a placental abruption, poses a serious risk to you and your baby. Vaginal bleeding can also occur if you have a placental abruption.
As your baby grows, your abdomen must expand to make room for your expanding uterus. Toward the end of your pregnancy, you may experience a persistent tightness due to the cramped quarters shared by your baby and your abdominal organs. Large meals, intestinal gas and constipation may also cause occasional feelings of tightness in your abdomen.
When to Seek Medical Help
If you have tightening sensations 4 or more times in an hour and are more than 3 weeks from your due date, call your doctor immediately. If your abdomen becomes very tight and the tightness doesn't relax after a few minutes -- especially if you feel pain -- seek immediate medical attention.