Journal of Ultrasound in Medicine, Vol 8, Issue 10 561-563, Copyright © 1989 by American Institute of Ultrasound in Medicine

JOURNAL ARTICLE

First trimester bradycardia. A sign of impending fetal loss

L. A. Laboda, J. A. Estroff and B. R. Benacerraf
Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, Massachusetts.

Normal first trimester fetal heart rates rise from an average of 100 beats per minute (bpm) at 5 to 6 weeks to 140 bpm at 8 to 9 weeks. The heart rates of 65 consecutive first trimester fetuses between 5+ and 8+ weeks were measured to determine whether unusually slow first trimester fetal heartbeats are associated with a poor outcome. All five pregnancies in which heart rates were below 85 ended in spontaneous miscarriage. This study suggests that first trimester bradycardia may be associated with a poor prognosis for the pregnancy.

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