Fetal heart rate

In euploid fetuses the heart rate increases from about 110 bpm at 5 weeks of gestation to 170 bpm at 10 weeks and then gradually decreases to 150 bpm by 14 weeks.

In trisomy 21 the FHR is mildly increased and is above the 95th centile in about 15% of cases.

In trisomy 18 the FHR is mildly decreased and is below the 5th centile in about 15% of cases.

In trisomy 13 the FHR is substantially increased and is above the 95th centile in 85% of cases.