CTS is common in pregnancy and can occur in 31% to 62% of people who are pregnant. Researchers aren’t sure why CTS is so common in pregnancy. They speculate that pregnancy-related hormones might contribute to increased swelling throughout the body.
Various things can cause pain in the middle of the bicep, which is the muscle at the front of the upper arm. Muscle strains and bruises, for example, are common causes of bicep pain.