Slow embryonic heart rate in early first trimester: indicator of poor pregnancy outcome.
OBJECTIVE
To assess the outcome of early first-trimester pregnancies with slow embryonic heart rates.


METHODS
Forty pregnant women had prenatal ultrasound scans obtained before 8 weeks gestation that demonstrated an embryonic heart rate of 90 beats per minute or less. Follow-up information was used to determine pregnancy status at the end of the first trimester.


RESULTS
Thirty-two embryos died before the end of the first trimester, five survived the first trimester, and three were lost to follow-up. Fetal demise occurred in all seven embryos with heart rates of less than 70 beats per minute, 10 of 11 with heart rates of 70-79 beats per minute, and 15 of 19 with heart rates of 80-90 beats per minute. All 32 pregnancy losses occurred within 10.5 weeks gestation.


CONCLUSIONS
An embryonic heart rate of 90 beats per minute or less early in the first trimester carries a dismal prognosis, with a very high likelihood of fetal demise before the end of the first trimester. Demise occurred in all embryos with heart rates less than 70 beats per minute.
Department of Radiology, Harvard Medical School, Boston, MA.
C B
CB
Benson
P M
PM
Doubilet
D005260:Female; D005313:Fetal Death / Q000175:diagnosis*; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011379:Prognosis