Introduction
Labor onset can be spontaneous or induced with regular or rhythmic
uterine contractions. Prolonged labor, especially latent phase, has been
associated with increased risk of caesarian deliveries, need for
intrapartum interventions, adverse fetal outcomes such as poor APGAR
scores at 5 minutes, and admission to newborn intensive care units
(NICU) [2,3]. There are some inconsistencies in defining the active
phase of labor. In 1978, Friedman observed that active labor started
when there is a significantly increased rate of change in cervical
dilation [4]. In the 2003 American College of Obstetrics and
Gynecologists (ACOG) practice bulletin on approaches to limit
intervention during labor and birth, it has been noted that most
clinicians defined the active phase of labor at 3 or 4 cm cervical
dilation [5]. Also, the 1998 World Health Organization partograph
defined the beginning of an active phase of labor at 3 cm with a
cervical dilation rate of at least 1 cm per hour [6]. However,
recent evidence suggests that defining active labor at cervical
dilatation of 5 or 6 centimeters may have similar obstetric outcomes as
cervical dilatation happens substantially slower than originally
reported by Friedman in his 1978 published book [7]. Zhang et al. in
2002 reported a substantially slower rate of dilation from 4-10 cm (5.5
hours) compared to what was reported by Friedman (2.5 hours) in 1978,
with the 3-4 cm diagnostic criteria for active labor found to be too
stringent for nulliparous parturients [8]. A follow-up study by
Zhang et al. (2010) and Laughon et al. (2014) also reported
substantially lower rates of dilation (0.5-0.7 cm per hour) compared to
Friedman’s (1 cm per hour) [8,9], supporting earlier findings that
the 3-4 cm diagnostic criteria for active labor might be too stringent.
Guided by this new evidence, ACOG released a new diagnostic criterion
for the active phase of labor in an obstetric care consensus statement
in 2014, which advocated for adopting 6 cm cervical dilation as the
threshold for the onset of the active phase of labor for most women
[10] and late r on supported by the World Health Organization (WHO)
in 2018 [11]. However, the feasibility and obstetric outcomes of
defining the active phase of labor at cervical dilation of 6 compared to
4 centimeters in low-resource settings have not been evaluated. This
study sought to compare the obstetrics outcomes of parturients whose
active stage of labor was defined at a cervical dilation of 4 cm
compared to 6 cm in Kenya.