How bad is low back pain in early pregnancy ?

Minimal: Low back pain in pregnancy is usually a problem in late pregnancy when the size of the baby causes a shift in the mother's posture (belly out; lower back more curved than usual) that puts a strain on the muscles of the lower back. Some women feel beginning labor in the back but that has adifferent quality.

Third trimester : The bad period is the third trimester especially if you are small and have cephalopelvic disproportion. The sacroiliac joints are stressed as the pelvic inlet widens to accommodate the enlarging fetus.