Antepartum sinusoidal and decelerative heart rate patterns in Rh disease.

A review was made of the data on 42 cases of Rh disease that resulted in the birth of a live infant after 33 weeks' gestation. On 12 occasions, antepartum monitoring of fetal heart rate (FHR) showed a sinusoidal and/or decelerative heart rate pattern. All 12 infants were anemic at birth; only one was born acidotic. One infant died neonatally. Monitoring of FHR identified the severely affected infant more reliably than did the Liley classification. Within the same Liley group, infants with an abnormal heart rate tracing had lower values of hemoglobin at birth than did infants with a normal tracing. The conclusion is that a decelerative heart rate pattern is just as indicative of an infant severely affected with Rh disease as is the sinusoidal pattern. Once the abnormal heart rate pattern is identified, early delivery nearly always results in an infant who survives.