Will Heart Rate Predict Gender?


It’s not uncommon to want to know your baby’s gender, even before you hit that 20-week ultrasound where you will usually find out.

So many myths surround gender prediction that it’s often difficult to discern the real from the surreal.  Of all the pregnancy myths, gender prediction myths are probably the most encountered. The most common of these rely on fetal heart rate to predict whether the baby will be a boy or a girl.

There are some expectant mothers who declare that a heart rate of 140 beats per minute indicates a girl; others swear that the cut-off is the 150 mark. The truth of the matter is that a normal fetal heart rate fluctuates between 120 to 160 beats per minutes. In fact, if measure the fetal heart rate at ten minute intervals during an hour, you might just get six different heart rates, some below 140 beats and others below 140.

This variation has more to do with the developing fetal brain than the genitalia (although some would argue that the male brain and genitalia are one in the same.) The fetus’ brain is controlled by the sympathetic nervous system (the flight or fight response) and the parasympathetic system (relaxation.) As the fetus develops, these two systems engage in a power struggle. The heart rate speeds up when stimulated by the sympathetic system, and slows down when controlled by the parasympathetic response. We usually listen to the fetal heart for about ten to thirty seconds at a time in the office. If the baby is moving, the rate may be higher than if it were sleeping. 

This variation also applies to men and women, boys and girls, none of whom have different heart rates based on gender. If someone stood behind a curtain, for instance, and I told you that person’s heart rate, you would not be able to determine if that person were male or female.  The same holds true for an unborn baby.  Thus, science again rears its materialistic head and claims this myth is simply not true.  The wonderful thing to remember is that your baby does not easily fit into some descriptive box, and he or she is as individual as you are.