Sonographic estimation of fetal heart rate in healthy pregnant women in Umuahia South East Nigeria

Abstract

Abstract Introduction: There are various methods of estimating fetal heart rate (FHR) in pregnancy such as the use of fetoscope, sonicaid, and others. Of all these methods, Doppler ultrasound evaluation of FHR is preferred because it is real in time, readily available, does not involve the use of ionizing radiation, is cheap, reproducible and is not observer dependent. It does not have any deleterious effect on the fetus, it also shows the fetal cardiac tracing and rhythm such that FHR and heart sound can be heard and calculated. This can help in determining abnormal fetal heart sound.[1,2] There is not much previous work on the ultrasound estimation of FHR in pregnant women in Umuahia and hence the need for this study. Aim: The aim of the study is to establish normal ranges of FHR in healthy pregnant women using Doppler-guided ultrasound estimation, to correlate it with the gestational age (GA) and estimated fetal weight (EFW). Materials and Methods: This is a randomized prospective study of 110 healthy singleton pregnant women on their routine antenatal visit. Data on GA were obtained using the crown-rump length in the first trimester and biparietal diameter (BPD) and femur length (FL) in the second and third trimesters. FHR was obtained using Doppler interrogation of the heart while the weight of the fetus was obtained using three parameters; the FL, abdominal circumference, and the BPD. Results: The result obtained from the data was analyzed using Statistical Package for Social Sciences (SPSS) version 21. Mean, minimum, and maximum values were obtained. The relationship between the FHR, EFW, and GA was correlated. The minimum GA was n = 10 weeks while the maximum GA was n = 40 weeks with a mean value of 30. The minimum fetal weight was observed to be n = 35 g while the maximum fetal weight was n = 4402 g and the mean value was 1923.8 the minimum FHR obtained from this research was n = 125 bpm and the maximum = 176 bpm while the mean was observed to be 143.4. Conclusions: In summary, the FHR is affected by the EFW and the GA in such a manner that as the fetal weight and GA increase, the FHR decreases and vice versa. The FHR ranges from 125 bpm to 176 bpm in a healthy pregnant woman.