Your expanding uterus shifts your center of gravity and stretches out and weakens your abdominal muscles, changing your posture, and putting a strain on your back. It may also cause back pain if it's pressing on a nerve. In addition, the extra weight you're carrying means more work for your muscles and increased stress on your joints, which is why your back may feel worse at the end of the day.
Read this guide Checking posture during pregnancy
What's more, hormonal changes in pregnancy loosen your joints and the ligaments that attach your pelvic bones to your spine. This can make you feel less stable and cause pain when you walk, stand, sit for long periods, roll over in bed, get out of a low chair or the tub, bend, or lift things.
You're not alone. As many as three-quarters of pregnant women experience back pain at some point. Most often the pain appears in the later months or becomes worse as the pregnancy progresses. It may also persist after the baby arrives, but the postpartum back pain usually resolves in a few months.
The good news is that there's no link between back pain and pregnancy outcome.
Bottom Line
Back pain is very common. It often occurs earlier in pregnancy than people would expect, is the result of a complex set of changes in a pregnant woman's physiology, and typically improves with some simple treatment steps. Women who develop this type of back pain should find strategies that work for them to relieve the symptoms since the problem may not go away completely during pregnancy and may take months or longer after delivery to fully resolve.
Bottom Line
Back pain is very common. It often occurs earlier in pregnancy than people would expect, is the result of a complex set of changes in a pregnant woman's physiology, and typically improves with some simple treatment steps. Women who develop this type of back pain should find strategies that work for them to relieve the symptoms since the problem may not go away completely during pregnancy and may take months or longer after delivery to fully resolve.