According to the Friedman curve revised criteria (Zhang et al., 2010) for active labour, which threshold of cervical dilation marks the onset of the active phase in nulliparous women?
- A 3 cm
- B 6 cm ✓
- C 4 cm
- D 5 cm
Correct answer: B. 6 cm
Explanation
Zhang et al. (2010) reanalysed contemporary labour data and found that active labour acceleration (the active phase of cervical dilation) does not begin reliably until 6 cm dilation, rather than the historical 4 cm (Friedman's threshold). This led ACOG and SMFM to revise guidelines in 2014, recommending that the active phase of labour begins at 6 cm, and that cesarean delivery for active phase arrest should not be performed before 6 cm dilation with inadequate contractions unresponsive to oxytocin.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.