HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text All Versions of this Article: 2362040880v1 236/2/643    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Doubilet, P. M. Articles by Benson, C. B. Search for Related Content PubMed PubMed Citation Articles by Doubilet, P. M. Articles by Benson, C. B.

Outcome of First-Trimester Pregnancies with Slow Embryonic Heart Rate at 6–7 Weeks Gestation and Normal Heart Rate by 8 Weeks at US¹

From the Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, 75 Francis St, Boston, MA 02115. Received May 18, 2004; revision requested August 3; revision received August 24; accepted October 1. Address correspondence to P.M.D. (e-mail: Pdoubilet{at}Partners.org).

PURPOSE: To determine retrospectively the outcome of pregnancies in which the embryo has a slow heart rate at 6.0–7.0 weeks gestation and a normal heart rate at follow-up ultrasonography (US) by 8.0 weeks gestation.

MATERIALS AND METHODS: Institutional review board approval was granted; informed consent was not required. The study was Health Insurance Portability and Accountability Act compliant. Singleton pregnancies with an embryonic heart rate measured on a 6.0–7.0-week US scan were identified. The heart rate was classified as slow if it was fewer than 90 beats per minute prior to 6.3 weeks or fewer than 110 beats/min at 6.3–7.0 weeks, normal if it was 100 or more beats/min at less than 6.3 weeks or 120 or more beats/min at 6.3–7.0 weeks, or borderline if it was 90–99 beats/min prior to 6.3 weeks or 110–119 beats/min at 6.3–7.0 weeks. Pregnancies were excluded from the analysis if they were lost to follow-up before the end of first trimester. The Fisher exact test was used for all statistical comparisons.

RESULTS: The rates of first-trimester demise were 60.6% for pregnancies with slow heart rates at 6.0–7.0 weeks (188 of 310), 17.4% for those with borderline heart rates (103 of 593), and 9.1% for those with normal heart rates (186 of 2034). There were 59 pregnancies with a slow heart rate at 6.0–7.0 weeks and a normal heart rate at follow-up US by 8.0 weeks; 15 (25.4%) resulted in first-trimester demise. This rate of demise was significantly higher than that of 7.2% (28 of 390) in pregnancies with a normal heart rate at 6.0–7.0 weeks and a normal heart rate by 8.0 weeks (P <.001, Fisher exact test). Pregnancies with a borderline heart rate early in pregnancy followed by a normal heart rate had a demise rate of 7.6% (nine of 118), which is similar to those with normal heart rates early in pregnancy followed by normal heart rates at follow-up (P = .84).

CONCLUSION: When a slow embryonic heart rate is detected at 6.0–7.0 weeks, the likelihood of subsequent first-trimester demise remains elevated (approximately 25%) even if the heart rate is normal at follow-up. In such pregnancies, at least one follow-up scan in late first trimester is warranted.

© RSNA, 2005