While it might feel awkward and could throw off your balance, bending over in the last three months of pregnancy will not hurt you or your baby in any way. Your baby is well protected by the abdominal wall and muscles, the uterine wall -- which is also composed of muscle -- and the amniotic fluid around him. Bending during this phase of pregnancy is not contraindicated, however it increases your risk of falling and may cause other discomforts.
Risks of Falling
The biggest risk of bending over is the risk of falling. Falls can cause trauma if you fall directly on your abdomen. This trauma can cause placental abruption -- or separation from the uterine wall, which causes bleeding and lack of oxygen to the baby. The risk to the fetus from falls increases during the third trimester, when the uterine wall thins and the baby's head drops into the pelvis.
Bending over can send a rush of blood to your head, which could make you dizzy. The risk of becoming dizzy is not that it harms the baby, but that it could make you pass out, which brings you back to the main risk in late pregnancy from bending --falling to the ground.
Bending over puts extra weight on your back. Since many pregnant women have back pain just from carrying around the extra load in front, putting even more strain on your back won't hurt the baby but could pull a few muscles for you. Good body mechanics stress bending at the knees to avoid straining your back.
Bending over can increase the symptoms of heartburn, a common complaint in late pregnancy. You may experience acid reflux, the flow of acid from the stomach into the esophagus, when you bend over because bending increases pressure on the stomach. Heartburn causes burning pain, belching and an unpleasant taste in your mouth.