Low beta-hCG is associated with poor prognosis in association with an embryo with positive cardiac activity.

Seven pregnancies with positive fetal heart activity and low or very low serum beta-human chorionic gonadotropin (beta-hCG) levels were investigated. The gestational age by dates was between 6 weeks 3 days and 8 weeks 4 days at the time of the first ultrasound scan and beta-hCG ranged between 282 and 10,000 mIU/ml of the Second International Standard. The crown-rump lengths ranged between 6 and 13 mm and heart activity was always detected. Four cases were scanned because beta-hCG was lower than that expected for the gestational age; in these cases the yolk sac was present but the gestational sacs were small, with a trophoblastic ring that looked thin and subjectively seemed abnormal. The beta-hCG level was measured in the other three cases, because the gestational sacs were small and had a thin trophoblastic ring. In these cases, fetal heart activity was clearly imaged. All cases were scheduled for a repeat ultrasound scan 2 weeks later. Three cases aborted spontaneously the following week, whereas in the other four no heart activity was detected in a repeat sonogram 2 weeks later. Low serum beta-hCG levels indicate a poor prognosis even when associated with an embryo with positive cardiac activity detected ultrasonographically.