Increased incidence of infections
There are several types of leukemia, and they affect the number of white blood cells. These cells are responsible for fighting infections, and even though they multiply rapidly, these new circulating cells are immature, and they do not work properly. Thus, you start having more frequent viral or bacterial infections, depending on which type of blood cell is involved in leukemia.
In women, this symptom might be a bit more difficult to detect because they have more frequent urinary infections than men. Thus, pay attention if you start having more frequent urinary infections than usual. Ask your doctor about them. It might not be leukemia but kidney stones or another disease that explains such a regular incidence.