Pain at the base of the left thigh in late pregnancy may be normal. Firstly it is caused by the enlargement of the uterus in late pregnancy, which increases the load on the hip joint or presses on the associated nerves. Secondly, if a pregnant woman has a separation of the pubic symphysis, this may also cause pain. Some pregnant women in late pregnancy may experience tightness and swelling in the abdomen on the eve of labour, and may also experience back and leg pain.