The differences of fetal heart rate according to fetal sex

Lee, Young; Baik, Eun Jeong; Shin, Jong Chul; Chung, Dae Young; Kim, Soo Pyung; Kim, Chang Yee; Moon, Hee Bong; Yi, Chong Seung

Abstract

OBJECTIVES
The purpose of this study is to analyze the previously unreported effect of fetal sex on the fetal heart rate and to measure its magnitude in relation to the effects of other independent clinical variables.
METHODS
Three hundred and seventeen pregnant women who were able to provide electronic fetal heart rate monitoring were evaluated. On the basis of fetal sex after birth, 167 pregnant women who delivered male neonate were for males group and 146 examples who delivered female neonate were for female group. We analyzed fetal heart rate data using the Catholic Computer Assisted Obstetric Diagnosis System(CCAOD).
RESULTS
Female fetuses had significantly faster basal heart rate(140.51+/-12.43bpm) than male fetuses(137.64+/-13.68 bpm).(P=0.007) Percent acceleration time(PAT) increased significantly for males(6.10+/-4.00bpm), comparing to females(4.90+/-3.34bpm).(P=0.001) Also percent deceleration time(PDT) was significantly higher in male fetuses(7.50+/-8.70bpm) than female fetuses(6.18+/-7.70bpm).(P=0.039) But there was no differences in standard deviation(SD)(8.84+/-10.11bpm, 8.11+/-3.56bpm), long term variation(LTV)(80.38+/-62.79msec, 73.65+/-54.60msec), and short term variation(STV)(14.06+/-9.79msec, 13.33+/-12.32msec) between male and female fetuses.
CONCLUSION
The fetal heart rate of female fetuses differ from that of male fetuses. Computerized linear analysis and nonlinear analysis of antepartum fetal heart rate will need to take into account the multiple factors that influence the fetal heart rate to identify precisely which pattern predict clinical outcome.