Normal Range of Uterine Contractions in CTG

Defining Normal Contraction Frequency

• The American Academy of Family Physicians defines normal uterine contractions as no more than 5 contractions in a 10-minute period, averaged over a 30-minute window 1, 2, 3
• Normal uterine activity during labor is defined as ≤5 contractions per 10 minutes (averaged over 30 minutes), while >5 contractions per 10 minutes is classified as tachysystole 1, 2, 3

Assessment Parameters Beyond Frequency

• When evaluating uterine contractions on CTG, clinicians should assess multiple characteristics beyond just frequency, including rate and rhythm, duration, intensity, and resting tone between contractions 1
• An intrauterine pressure catheter (IUPC) should be used if accurate assessment of contraction strength is clinically necessary, as external transducers have limitations in measuring amplitude 1, 2, 3

Clinical Context and Tachysystole

• Tachysystole must be qualified by the presence or absence of fetal heart rate decelerations, as this determines clinical significance and urgency of intervention 1, 2, 3

Important Caveats

• Contraction patterns do not reliably distinguish latent from active phase of labor or differentiate true from false labor, according to the American Journal of Obstetrics and Gynecology 4
• Serial cervical examinations remain the gold standard for assessing labor progress, not contraction quantification alone, as recommended by the American Journal of Obstetrics and Gynecology 4