Understanding the Stages of Labor: Why Modern Research Has Changed How We Define Progress

By Birth & Baby University · Last updated: October 2026 · 5 min read

Many doulas learned the stages of labor as a tidy sequence: dilate at about a centimeter an hour, then push. Researchers have spent the last fifteen years showing that real labors do not follow that line, and guidelines have shifted. This article explains what changed, what remains debated, and how to talk about progress with families.

Key takeaways

• Large modern datasets show slower early progress and faster progress later than the traditional curve implied.
• WHO’s Labour Care Guide places the start of the active phase at 5 cm, and ACOG’s 2024 guideline replaced its 2014 consensus on labor management.
• Randomized evidence comparing the old and new approaches found no clear difference in intrapartum cesarean use, so the debate is not settled.
• Whether labor is “on track” is a clinical judgment. Your role is to help families understand the reasoning and ask questions.

What the research says

Where the old curve came from and why it was questioned

The traditional partograph traces back to work in the 1950s and 1970s. A 2025 FIGO position statement notes that WHO endorsed its use in 1994 based on a multicenter trial showing less prolonged labor, augmentation, emergency cesarean and intrapartum stillbirth. In 2020 the WHO launched the Labour Care Guide, which treats the active phase as starting at 5 cm, and FIGO recommends universal adoption.

The challenge came from data. A large U.S. analysis of 62,415 spontaneous labors with normal neonatal outcomes found that progress from 4 to 5 cm could take more than 6 hours and from 5 to 6 cm more than 3 hours, that nulliparous and multiparous people progressed at a similar pace before 6 cm, and that labor accelerated much faster after 6 cm for those who had given birth before. The authors suggested that allowing more time before 6 cm might reduce intrapartum and later repeat cesarean births. The 95th percentile of second stage was 3.6 hours with epidural and 2.8 hours without in nulliparous people.

How guidelines responded

The 2014 ACOG obstetric care consensus on preventing primary cesarean listed labor dystocia as the most common indication for primary cesarean and said it may be necessary to revisit the definition because contemporary labor progresses substantially slower than historically taught. That consensus has since been replaced by ACOG Clinical Practice Guideline No. 8 (2024), which defines labor and labor arrest and gives graded recommendations for dystocia in the first and second stages. Its recommendations include that cervical dilation of 6 cm be considered the start of the active phase (strong recommendation, moderate-quality evidence); that active phase arrest be defined, with ruptured membranes, as no cervical change at 6 cm or more despite 4 hours of adequate contractions or 6 hours of inadequate contractions with oxytocin (conditional, low-quality evidence); and that a prolonged second stage be defined as more than 3 hours of pushing for first-time birthing people and 2 hours for those who have given birth before, with an individualized approach before diagnosing arrest (strong, high-quality evidence). The guideline text also describes a normal latent phase as varying widely, a prolonged latent phase as longer than 16 hours for first-time birthing people, and says most people with a prolonged latent phase enter active labor with expectant management. It recommends that pushing begin when full dilation is reached and that neuraxial anesthesia be offered in any stage. This article read the guideline’s free full text on 16 October 2026; a March 2025 correction to the guideline exists, and its text could not be read.

What happened when the approaches were compared

The Norwegian Labour Progression Study randomized 14 obstetric units to follow either the WHO partograph or Zhang’s guideline. Among 7,277 nulliparous people in spontaneous active labor, intrapartum cesarean occurred in 5.9% with the partograph and 6.8% with Zhang’s guideline, a difference that did not reach statistical significance (adjusted relative risk 1.17, 95% CI 0.98 to 1.40). Rates in both groups were lower than the roughly 9% seen before the trial. A follow-up analysis of the same trial found no difference in childbirth experience scores. Importantly, the trial did not show that the newer guideline lowers cesarean use, and it was cluster randomized without masking of staff.

Observational work points both ways. A single-center hospital cohort of 3,665 births found that labor arrest under either set of criteria was associated with higher maternal morbidity than normal progress, and that maternal and neonatal outcomes did not differ between the Friedman and Zhang criteria. Its authors suggested the change may reduce cesarean rates without more morbidity, while acknowledging a retrospective design.

What this means for doulas

• Replace the clock with a range. Tell families that early labor can take many hours and that care teams now often allow more time before concluding labor has stalled.
• Do not judge progress yourself. Cervical checks and the decision that progress is insufficient belong to the clinicians. Notice how your client feels and help them ask what the team is seeing and why.
• Expect different local practice. Hospitals and midwifery practices may use different labor curves, and a client who has read one guideline may meet another.
• Avoid “natural pace” slogans. Slower is not always fine. Arrest and prolonged labor are associated with more maternal morbidity in the observational work cited above, so the right message is “let’s understand the plan,” not “wait it out.”

Putting the evidence into practice

• During prenatal visits, explain that labor progress is not linear and that families may hear different definitions from different clinicians.
• Encourage clients to ask, early in labor, how the team will decide whether progress is adequate and what options exist if it slows.
• When progress slows, offer comfort, rest and position options within your scope, and help the family hear and weigh the team’s recommendation.
• Keep language like “typical” and “range” in your vocabulary. Avoid “should be dilating by now.”

The bottom line

The stages of labor are a useful teaching frame, but the timelines attached to them have been revised. Newer data describe a slower, then faster, pattern, and guidelines are adapting while trials have not shown that one approach clearly outperforms the other. Doulas help most by teaching flexibility, supporting informed questions and leaving assessment to the clinical team.

This article is for professional education. It is not medical, legal or tax advice. Check the standards of your certifying organization and the rules where you work.

Sources and further reading

• Zhang J, et al. Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstetrics & Gynecology 2010. Read the source
• American College of Obstetricians and Gynecologists. Obstetric Care Consensus No. 1: Safe prevention of the primary cesarean delivery. Obstetrics & Gynecology 2014. Read the source
• ACOG Committee on Clinical Practice Guidelines-Obstetrics. First and Second Stage Labor Management: ACOG Clinical Practice Guideline No. 8. Obstetrics & Gynecology 2024. Read the source
• Bernitz S, et al. The frequency of intrapartum caesarean section use with the WHO partograph versus Zhang’s guideline in the Labour Progression Study (LaPS): a multicentre, cluster-randomised controlled trial. Lancet 2019. Read the source
• Nunes JP, et al. Concerns about the contemporary labor curves and guidelines: Is it time to revisit the old ones? Eur J Obstet Gynecol Reprod Biol 2022. Read the source
• Ubom AE, et al. FIGO position statement on the use of the WHO labor care guide versus the partograph. Int J Gynaecol Obstet 2025. Read the source
• Rozsa DJ, et al. The effect of Zhang’s guideline vs the WHO partograph on childbirth experience measured by the Childbirth Experience Questionnaire in the Labor Progression Study (LaPS): a cluster randomized trial. Acta Obstet Gynecol Scand 2022. Read the source

If you want structured training in supporting families through labor, see the birth doula training and mentorship options on the For Doulas page.

More for professionals: the Professionals Blog.