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.
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
