The predictive validity of fetal/embryonic heart monitoring during the first trimester in assessing the pregnancy outcomes

Objective To explore the pregnancy outcomes in women whose fetal/embryonic heart rate(FHR) were below 120 beats per minute(bpm) before 8 weeks pregnancy and determine the predictive value of FHR in pregnancy outcome. Methods The laboratory examinations, clinical data and clinical history of the pregnant women whose FHR were below 120 bpm before 8 weeks pregnancy were retrospectively analyzed. Results When gestational age(GA)was less than 8 weeks, pregnancy loss was observed in 11.0% (110/998) cases with an FHR less than or equal to 120 bpm, and pregnancy loss occurred in all the cases (23/23) with an FHR less than or equal to 70 bpm. The proportions of first trimester loss were 86.4% (19/22) for pregnancies with an FHR of 71-80 bpm, 75.7% (28/37) for pregnancies with an FHR of 81-90 bpm, 25.5% (14/55) for pregnancies with an FHR of 91-100 bpm, 6.3% (13/208) for pregnancies with an FHR of 101-110 bpm, and 2.0% (13/653) for pregnancies with an FHR of 111-120 bpm.ROC analysis showed that the best cut-off value to predict adverse pregnancy outcomes was an FHR of 94 bpm. The area under the ROC curve was 0.906 (P<0.0001) and its sensitivity and specificity values were 97.86% and 71.43% respectively. Conclusions Fetal/embryonic heart monitoring before 8-weeks pregnancy can be an effective predictor for early pregnancy outcome. The best cut-off value to predict adverse pregnancy outcomes is an FHR of 94 bpm. Key words: Ultrasonography; Heart rate, fetal; First trimester; Pregnancy outcome