Q – I have read in 3 different pregnancy books that you should not sleep on your back when you are pregnant. Why is this? I am 7 months pregnant and that is pretty much the only position that is comfortable for me! Can you tell me what the deal is?

A – Books tell us not to lie on our back while sleeping because the big vessels that supply the legs and uterus with blood and then take it away, the aorta and inferior vena cava, lie adjacent to the spine.  It was thought that lying on the back would decrease the blood flow to the uterus and hence the baby thus possibly causing trouble for the baby.  In actual fact, while the anatomy is correct, the majority of women have no problems with lying on their back in pregnancy.  If there is a question of decreased growth of the fetus or the mother’s blood pressure is elevated we do suggest that women not lie flat on their back but lie with a small wedge or pillow under the right or left side to shift the uterus off the vessels.  This wedge only has to be about two inches at its deepest point and about l/4 inch at the thinnest point.  The wedge is placed under her side at about waist level with the wide part at the side of the body and the thin part closest to the spine.  This is enough to take the pressure off the great vessels but still allows even at risk women to sleep on their back.

Dr. Linda Ducholke, a mother of two, has been a successful Family Practitioner with Obstetrical privileges for the past 20 years. The main focus and passion of her practice is obstetrics and childcare.