Many factors affect the development of a fetus into a healthy child, some which are beyond your control and others that are within your control. Here are ten of the most common pregnancy risk factors that can be controlled or influenced:Smoking - Smoking is not only bad for you, but bad for your baby as well. Smoking during pregnancy reduces the amount of oxygen that the baby receives and increases the risk of miscarriage, bleeding, and morning sickness. Chemicals inhaled while smoking may lead .