There are so many reasons why you could be 33 weeks pregnant with lower back pain. It is normal that you will have a lot of pressure thanks to the growing uterus. The pressure will be added onto your spine and by the time you are in your third trimester you may be suffering from lower back pain. You are morel likely to suffer from lower back pain if you are have been suffering from lower back pain in your previous pregnancies or if you have had this condition before pregnancy. One of the reasons you could be having lower back pain when you are pregnant includes the exercises you perform. Yoga may be good for your pregnancy, but if you are always lying on your back and stomach, you will be exerting undue pressure on your lower back, leading to lower back pain, you could also be having lower back pain in your pregnancy if you are sleeping in the wrong position and exerting undue pressure on your back at the same time. Sleep on your side when you are pregnant, preferably on your left side to relieve the pressure of your uterus on your lower back. This will ensure that you are not in extreme pain when you walk or climb your stairs. Make sure you have supported your weight by putting pillows underneath your back or belly. Whatever works for you here will go. Make sure you are as comfortable as possible. Most of the time, if the pain is caused by the weight of the pregnancy; it will disappear as soon as you give birth. Take rests, but while it may be great for your back, too much of it may bring you problems with your back later on. Perform exercises to strengthen your back.