The present invention provides a method for determining the gender of an unborn child by assaying the overall reducing/oxidizing or redox activity of the maternal urine or other body fluid. The method can be used to determine fetal gender at any time point during the entire pregnancy, the earliest being the first day of a missed menstruation. The body fluid may be processed before assaying. Processing may involve aging the body fluid, or purification of various fractions. The methods of the present invention also provide for a means for pre-conception baby gender planning by assaying the overall redox activity of a non-pregnant female's urine or other body fluid. The overall redox activity of a urine sample correlates with the gender specific compatibility of the ovum being released during a particular menstrual cycle. Therefore, assaying the overall redox activity of a non-pregnant female's urine will help a couple conceive a baby having a desired gender.
