The heart rate signal contains information about the condition of the heart [
]. One of the features which information can be obtained from the heart rate signal is its chaotic behavior and it may be useful in disease diagnosis of the heart. It is known that a healthy heart, like many other biological systems, has chaotic behavior. This fact is also manifest in the heart rate signal [
]. Among all heart related problems, one of the major problems, facing doctors, has always been the heart related diseases which happen before birth and are not accurately diagnosed until after the birth. Sooner diagnosis will definitely lead to better decision making by doctors. In the present research study, the main purpose is introducing a method for disease diagnosis of fetus before birth. In the procedure of the present research, first the data should be obtained from the heart rate signal and second, the analysis on the signal should be done. Through our work the chaotic analysis are done by means of Matlab programming based on Box Dimension method which is a sub method of fractal dimension and also analysis based on Lyapunov Exponent. A mathematical introduction to Fractal Dimension and Lyapunov exponent is also given in the main paper.