Table 1.

Operationalized active labor diagnostic guidelines for labor state categorization at hospital admission

Source	Diagnostic criteria
Friedman 2,5	Cervical dilation rate ≥1.2 cm/h during the first hour after admission that led to dilatation ≥3 cm, or progression from an earlier dilatation to complete dilatation within 1 h of admissiona
National Institute for Health and Care Excellence7	Cervical dilation rate ≥ 2cm in 4 h (≥0.5 cm/h, on average) postadmission that led  to dilation ≥4cm, or progression from an earlier dilation to complete dilation  within 4 h of admissionb
American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine8	Cervical dilatation ≥6 cm but not completely dilated and regular uterine contractions at admission

^aSlope calculations based on cervical examinations immediately before and after the 1- h postadmission time point were used to approximate cervical dilatation (cm) at the 1- h time point, unless an examination was performed exactly 1 h after admission. The dilation slope (cm/h) during the first hour postadmission was then calculated for each woman to determine if she was in active labor.

^bSlope calculations based on cervical exams immediately before and after the 4- h postadmission time point were used to approximate cervical dilatation (cm) at the 4- h time point, unless an exam was performed exactly 4 h after admission. The dilation slope (cm/h) during the first 4 h postadmission was then calculated for each woman to determine if she was in active labor.