Normal Fetal Heart Rate at 12 Weeks Gestation
The normal fetal heart rate at 12 weeks gestation is 110 to 160 beats per minute, according to American Academy of Family Physicians guidelines. 1, 2
Baseline Normal Range
The established normal baseline fetal heart rate throughout pregnancy is 110 to 160 bpm, which applies from early gestation through term 1, 2
Research analysis of 78,852 cardiotocography tracings identified 120 to 160 bpm as the most accurate symmetric normal range, though the broader 110-160 bpm range remains clinically safe in daily practice 3
Bradycardia is defined as heart rate below 110 bpm, while tachycardia is defined as heart rate above 160 bpm 1, 4
Gestational Age Considerations
Fetal heart rate decreases slightly as gestation advances, so rates at 12 weeks may trend toward the higher end of the normal range 3
At 12 weeks gestation specifically, the uterus is just beginning to cause compression of maternal vessels (inferior vena cava and aorta), which can affect maternal hemodynamics but does not directly alter the normal fetal heart rate range 1
Important Clinical Caveats
Persistent tachycardia above 180 bpm is defined as tachyarrhythmia and requires further evaluation, as this exceeds normal physiologic variation 2
Maternal factors including fever, infection, anxiety, and certain medications can cause fetal tachycardia within or above the normal range 1
Fetal bradycardia at 12 weeks warrants investigation for potential conduction abnormalities, though transient bradycardia may occur with position changes 1
Supraventricular tachycardia (SVT) should be considered when fetal heart rate exceeds 200 bpm, as this represents true arrhythmia rather than physiologic tachycardia 5