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Embryonic heart rate in early pregnancy
T I Stefos1, D E Lolis, A J Sotiriadis
1Department of Obstetrics-Gynecology, University of Ioannina, Greece.
Journal of Clinical Ultrasound : JCU
|February 25, 1998
Summary
Embryonic heart rates between 6-8 weeks gestation predict first-trimester fetal outcomes. Lower heart rates, especially below 85 beats per minute, indicate a higher risk of pregnancy loss.
Area of Science:
- Embryology
- Perinatology
- Medical Ultrasound
Background:
- Embryonic heart rate (EHR) during early gestation is a critical indicator of development.
- Limited data exists on EHR in the 6-8 week gestational period.
- Understanding EHR can aid in predicting first-trimester fetal outcomes.
Purpose of the Study:
- To determine embryonic heart rates at four distinct stages between 6-8 weeks' gestation.
- To correlate EHR with fetal outcomes at the end of the first trimester.
- To establish the lower limit of EHR associated with favorable pregnancy outcomes.
Main Methods:
- Prospective study of 2,164 singleton pregnancies (1992-1995).
- Gestational age determined by last menstrual period and crown-rump length (CRL) via ultrasound.
- M-mode sonography used to measure mean EHR in beats per minute.
Main Results:
- Mean EHR increased with gestational age: 111±14 (42-45 days), 125±15 (46-49 days), 145±14 (50-52 days), 157±13 (53-56 days).
- Significantly fewer losses observed with EHRs of 116-125 bpm (early stages) and ≥146 bpm (later stages).
- Embryos with EHR <85 bpm during 6-8 weeks' gestation did not survive; fetal loss decreased linearly with increasing gestational age.
Conclusions:
- Embryonic heart rate during 6-8 weeks' gestation is a significant predictor of first-trimester fetal outcome.
- EHR can identify embryos at risk of non-survival.
- Specific EHR ranges are associated with optimal outcomes at different early gestational ages.