One of the popular theories on baby gender prediction is based on the baby’s heart rate.
The theory states that if your baby’s heart rate was 140 beats per minute and above, you would be having a girl. If the heart rate was under 140 beats per minute, then you would be having a boy.
While this would be a quick and easy baby gender prediction method, there is actully no evidence that this theory is accurate. There is recent study, “Sex, Heart Rate, and Age” from Terry J. DuBose, M.S., RDMS; Director Diagnostic Medical Sonography Program at the University of Arkansas for Medical Sciences, which indicates there is no correlation between fetal heart rate and the gender of the baby.