Many women believe that the gender of a baby can be predicted by how fast the baby’s heart beats either on an ultrasound or handheld doppler.
The theory says that:
- If the heartbeat is under 150, it’s a boy. Some people say under 140.
- If it’s over 150, it’s a girl. Some people say over 140.
However this way of predicting gender is actually a myth. Heartbeat can vary based on a lot of things, gender being the least of them. It can range from 100-160 beats a minute, but can change based on a range of factors.
The heartbeat of a baby does not stay the same at all times. If baby is stressed or is not receiving enough oxygen, awake or sleeping, their heartbeat can change.
If the heartbeat falls below 100 beats per minute, it’s called bradycardia. If the beats per minute rise above 160-180 minute, this is classed as tachycardia. Both can be signs of a problem.

Susannah is a certified Birth Doula through Childbirth International and the founder of Trimester Talk. With a background in journalism and digital strategy, she combines evidence-based research with real-world knowledge to create accessible content about pregnancy and parenting. She’s a mother of two and stepmother of two more, all of them now teenagers.