Hemorrhage would lead to a decreased preload and therefore decreased cardiac output.
Preload is simply the volume of blood that fills the heart as it gets ready to pump. More specifically, this is the end diastolic volume. Diastole meaning the relaxation of the heart muscles in order for it to expand and hence get filled with blood.
Cardiac output would refer to two things: stroke volume and heart rate. Stroke volume can simply mean the volume pumped by the heart towards the different parts of the body. Heart rate is the speed of the heart's beating. When there is hemorrhage, there is profuse or a lot of bleeding. This leads to a lower volume all in all inside the body.
