Fetal Heart Rate to Predict the Sex of Your Baby

Stethescope listening to pregnant belly
Fetal Heart Rate to Predict the Sex of Your Baby. Photo © Tetra images/Getty Images

"I have heard that you can predict the sex of your baby by using the heart rate of your baby during pregnancy. It was said that 140+ beats per minute (BPM) was a girl and under 140 BPM was a boy. Is this true?"

The Truth

This has actually been a pretty popular theory in gender prediction for a long time. The heart rate of your baby fluctuates as they grow and as they move. The fetal heart rates start slower, and then by 8-10 weeks the heart rates run in the range of 170-200 BPM (beats per minute).

 As you approach mid-pregnancy the average heart rates run between 120 - 160 BPM.

If your baby moves, his or her heart rate goes up, just as your heart rate does with movement. However, none of these is related to the sex of your baby. One's heart rate goes up during activity regardless of sex. Though what we are really looking at is the resting heart rate of your baby. To date, we have not found a difference in the heart rates of boys versus girls in pregnancy.

A study was actually done to test this theory. The study shows that there is no correlation between gender and fetal heart rate. Although they did find a correlation between heart rate and gestational age prior to 9.2 weeks.


A British study done in 1998 notes that "There is a widespread but erroneous view among the lay public that there is a difference in the baseline fetal heart rate between male and female fetuses." The scientists who conducted the study clearly assumed that the notion originated in folklore, but a scan of the medical literature over the past 30 years suggests otherwise.

For example, a similar study done 18 years earlier refers to "the hypothesis" that the sex of the fetus can be determined by fetal heart rate -- indicating that the idea had already won some credence within the medical community itself by that time. In fact, references to the hypothesis can be found in scientific studies dating back to 1969.

Electronic fetal monitoring burgeoned as an obstetrical tool between the late '60s and early '80s. It rapidly came to be seen as a sort of panacea for predicting all sorts of neonatal conditions and anomalies. More recent studies have called its usefulness into question.

"My labor nurse asked if we knew if we were having a boy or a girl when we were admitted in labor," says Amanda. "We told her we didn't. So when she put the fetal monitor on and looked at the heart rate, she said we were having a girl because it was high. She was wrong, but we got a good laugh about of it."

Interestingly enough, a study published this year in the American Journal of Obstetrics and Gynecology found that there is a difference in the heart rates of male and female fetuses during labor only. Scientists found that female fetuses had "significantly faster" heart rates than male fetuses after the onset of labor. It goes without saying that gender prognostications are fairly beside the point by the time birth is underway. -- David Emery


Bracero LA, Seybold DJ, Witsberger S, Rincon L, Modak A, Baxi LV. J Matern Fetal Neonatal Med. 2016 Mar;29(5):803-6. doi: 10.3109/14767058.2015.1019457. Epub 2015 Mar 10. First-trimester fetal heart rate as a predictor of newborn sex.

McKenna D, Ventolini G, Neiger R, Downing C. Gender-related differences in fetal heart rate during the first trimester. Fetal Diagn Ther. 2006;21(1):144-7.

OB/GYN.net. (2011, July 26). Sex, Heart Rate, and Age. Retrieved January 26, 2016, from http://www.obgyn.net/articles/sex-heart-rate-and-age

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