Running can become more uncomfortable when you're pregnant. It's not just the extra weight you carry in the pelvis, although that can contribute to pelvic discomfort. Pelvic discomfort also occurs from the normal physiological changes that occur during pregnancy. In some cases, pelvic discomfort could indicate more serious conditions that require medical evaluation. Talk to your doctor if you experience pelvic pain while running.
Physiological Changes
Pregnancy makes your joints more lax, including the sacroiliac joints and pubic symphysis. Your pelvis also tilts back so that the extra weight you carry in front during pregnancy doesn't cause you to fall flat on your face. Ligaments also stretch to accommodate the increased size of the uterus. All of these changes can cause pelvic pain in and of themselves, even if you don't run. Since running puts extra stress on the pelvic muscles and joints, you may feel more discomfort during or after a run. Pelvic changes start early in pregnancy — as early as eight weeks, according to "Massage Today" — due to the actions of hormones such as relaxin.
Extra Pelvic Weight
It's obvious that the size and weight of your uterus increase during pregnancy. The extra weight on your pelvis can cause discomfort when the uterus shifts as you run. The larger the baby grows, the more uncomfortable the extra weight becomes. By the last month of pregnancy, you may curtail running on your own because of the increased discomfort not only on your pelvis but also on your bladder when you run.
Contractions
Contractions may be felt as tightening low in the pelvis. If you feel discomfort that comes and goes at regular intervals, lasting 20 to 30 seconds at a time, you could be having contractions, especially if you notice abdominal tightening at the same time. Call your doctor immediately if you think you're having contractions before 37 weeks of pregnancy. Babies born before 37 weeks are considered premature and may have breathing and feeding problems, among other complications. When you run, put extra emphasis on staying hydrated, especially in warm weather; dehydration can cause preterm labor contractions.
Symphysis Pubis Dysfunction
Sometimes the ligaments that support the pelvic bone stretch more than they should, a condition known as symphysis pubis dysfunction. If this happens, you may feel like your legs are more separated than normal — because they are. Normally the pelvic bones have a 4 to 5 millimeter separation. During pregnancy, the gap increases by 2 to 3 millimeters, the BabyCentre website explains. In rare cases, the gap during pregnancy measures 10 millimeters or more, a condition known as diastasis symphysis pubis. You may feel unstable and have more pain on one side than the other. If you develop SPD, your doctor may not want you to run during pregnancy. You may experience too much pain when you run to put up much of a fight about stopping running.
