there are many possible reasons pregnant women may experience back or spinal pain. here are some of the more likely causes: weight gain. during a healthy pregnancy women typically gain between 25 and 35 pounds. this added weight must be supported by the spine which can result in discomfort in your lower back. further the weight of the growing baby and uterus puts pressure on the blood vessels and nerves in the pelvis and back. changes in posture. as your uterus becomes heavier your center of gravity changes. you may gradually -- perhaps without noticing -- begin to adjust your posture and the way you move. this may result in back pain or strain. hormone changes. during pregnancy your body produces a hormone called relaxin that allows ligaments in the pelvic area to relax and the joints to become looser in preparation for the birth process. the same hormone can cause ligaments that support the spine to loosen leading to instability and pain. muscle separation. as the uterus expands two parallel sheets of muscles (the rectal abdominis muscles) which run from the rib cage to the pubic bone may separate along the center seam. this separation may worsen back pain. stress. emotional stress can cause muscle tension in the back which may be felt as back pain or back spasms. you may find that you experience an increase in back pain during stressful periods of your pregnancy.
what causes back pain in pregnant women?