Can abnormal heart rhythms be detected with weekly fetal monitoring?

Yes: Weekly fetal heart monitoring is usually done for other reasons, like diabetes. Sometimes an abnormal heart rate is detected. Most of the time these are not significant.

Often: If the arrhythmia is intermittent, it may be difficult to detect with weekly monitoring. Most of the significant fetal arrhythmias are sustained and should be detected by an examination that includes an assessment of fetal heart rate and rhythm.