Headaches can be caused by pregnancy. Hormonal changes in the pregnant woman’s body are very significant during pregnancy, such as increased production of adrenaline, which can raise blood pressure or cause headaches. In addition, pregnancy produces many other hormonal changes, such as changes in mood, appetite, and other aspects of the body that can cause headaches. Pregnancy itself mainly causes hormonal changes in the body, and hormonal changes can cause headaches. Pregnancy itself does not cause headaches, it is the other hormonal changes brought about by pregnancy that cause headaches.