In the second trimester, the presence of back pain may indicate a calcium deficiency or a symptom of preterm labor. This is because in the second trimester, due to the rapid development of the fetus, pregnant women are easily deficient in various nutrients as well as minerals, especially calcium, vitamins and iron. Once deficient, it is easy to cause back pain and lumbago. When lumbago is accompanied by leg cramps and sciatica, besides taking calcium and vitamin B1 supplements, you should also consult your doctor for professional help. If the deficiency is mild, dietary supplementation is recommended. In the later stages of pregnancy, with the further development of the fetus and the gradual entry of the fetus into the pelvis, it can also lead to symptoms such as back pain. On the other hand, it is also important to note that premature babies usually have abdominal pain and other early entry into the pelvis. Therefore, in the second trimester, severe pain may be a symptom of preterm labor. If the pain is unbearable, it is advisable to go to the hospital for a checkup in time.