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Reference Intervals for First Trimester Embryonic/Fetal Heart Rate in a Thai Population
Author(s) -
Tannirandorn Yuen,
Manotaya Saknan,
Uerpairojkit Boonchai,
Tanawattanacharoen Somchai,
Wacharaprechat Teera,
Charoenvidhya Dhiraphongs
Publication year - 2000
Publication title -
journal of obstetrics and gynaecology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 1341-8076
DOI - 10.1111/j.1447-0756.2000.tb01341.x
Subject(s) - medicine , fetal heart rate , obstetrics , fetus , fetal heart , population , pregnancy , first trimester , heart rate , blood pressure , environmental health , genetics , biology
Objective: To establish reference intervals for first trimester embryonic/fetal heart rate in a Thai population. Methods: A prospective descriptive cross‐sectional study was performed on normal pregnant women registered at the antenatal clinic in their first trimester. All had a good menstrual history and the calculated gestational age using crown‐rump length (CRL) in the first trimester ultrasound was in agreement. Crown‐rump length and embryonic/fetal heart rate measurements were obtained by a 5 MHz vaginal probe combined with a duplex color Doppler machine. All of the newborns were proved to be normal at birth. We constructed and compared embryonic/fetal heart rate expressed as beats/min relating to gestational age (GA) (days) and CRL. The data was analyzed and the best fit mathematical model was derived using the SPSS computer program. Results: 547 cases were enrolled into the study. The median embryonic/fetal heart rate increased from 124 beats/min at GA of 40–44 days to 177 beats/min at GA 60–64 days, thereafter, embryonic/fetal heart rate gradually decreased to 159 beats/min at GA 95–99 days. The best fit regression equation was: embryonic/fetal heart rate (beats/min) = ‐ 21.666 + 5.4796 GA (day) ‐ 0.0383 GA (day) 2 , R = 0.5, p < 0.0001). In addition, embryonic/fetal heart rate also correlated with CRL. The median embryonic/fetal heart rate increased from 131 beats/min at CRL of 5–9 mm to 177 beats/min at CRL 20–34 mm, thereafter, embryonic/fetal heart rate gradually decreased to 155 beats/min at CRL 75–79 mm. The best fit regression equation was: embryonic/fetal heart rate (beats/min) = 127.361 + 3.4939 CRL (mm) ‐ 0.0749 CRL (mm) 2 + 0.0004 CRL (mm) 3 , R = 0.58, p < 0.0001). Conclusion: Reference intervals for first trimester embryonic/fetal heart rate in a Thai population were established. Our reference intervals may be useful for further studies, such as the prediction of spontaneous abortion or chromosomal disorders after ultrasound‐proven viability in the first trimester.