The Correlation Between Ultrasound-Measured Fetal Heart Rate and Gestational Age in a Normal Pregnant Nigerian Population

Abstract

A total of 400 apparently healthy pregnant women with singleton fetuses from Enugu, Southeast Nigeria were randomly selected for the study. The aims of the study are to establish: a normogram for fetal heart rate (FHR) and the relationship between fetal heart rate and gestational age (GA) by 2–D ultrasound. Crown rump length measurement was used for estimating GA in the first trimester while femur length and biparietal diameter measurements were used for estimating GA in the second and third trimesters. Result shows that the normal range of FHR was 120 to 162 beats per minute (BPM). There was a statistically significant negative correlation of FHR with GA in the first, second, third and combined trimesters as the coefficient of correlation, r = -0.652, -0.736, -0.8185 and -0883 respectively. The study shows that a unit increase in GA decreases the FHR by 32%, 15%, 12.6% and 13% in the first, second, third and combined trimesters respectively. Results suggest that FHR measurement should be done routinely as one of the essential parameters for the assessment of fetal well being by ultrasound.

Keywords: Fetal heart rate, Gestational age, Obstetric sonography

Nigerian Journal of Health and Biomedical Science Vol. 6 (1) 2007: pp. 73-77