( 8), whole-day monitoring of HR is an appropriate method for measuring physical activity and maturation but not for revealing any gender differences. HR is higher in male infants), and there is a developmental turn-around later in childhood when the HR of females increases?Ī methodologic problem also exists: Is “blind” monitoring (lacking behavioral control) of the ECG an adequate method for assessing gender-related differences in HR in neonates or infants, inasmuch as the behavior of the babies is usually variable? According to the results of Janz et al. Is the gender-related difference in HR absent in newborns and infants, developing only later? Or is the difference reversed at a particular stage of infancy, as Richards et al. ( 7), sequentially recording the ECG from 110 full-term infants up to 6 mo of age, found higher mean HR in male infants at 32–45 d and at 73–134 d but not earlier or later, independent of the size of the sample. HR was higher in siblings of SIDS victims, but gender did not significantly contribute to HR.
( 6) examined the developmental sequence of HR in 22 normal infants and 22 siblings of SIDS victims by using 12-h polygraphic recordings at the first week and at the first, second, third, fourth, and sixth months of age. ( 5) analyzed 9725 electrocardiograms recorded on the fourth day of life and reported that the gender-related differences in QT interval observed in the adult population are not present at birth. ( 4) examined 14 male and 17 female fetuses from 20 to 36 wk of gestation for 4-wk intervals and found no difference in HR according to gender at any age. ( 3) assessed HR of 212 fetuses between 14 and 41 wk of gestation and found no significant gender difference in the baseline fetal HR at any recorded gestational age (GA). However, studies with fetuses and infants have not yet revealed the same gender-related difference. Pearl ( 2) found the same pattern in 10–18-y-old children in whom corrected QT intervals (which varied directly with the HR) were significantly longer for girls than for boys. ( 1) found higher baseline HR in females, but this difference decreased with age. Baseline HR of human adults is gender-related.
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