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Developmental Biology - Labor & Delivery

Vaginal Births Labor More Slowly Than Expected

Spontaneous labor progression for vaginal births is slower than expected in many women...

Cervical dilatation during labor for vaginal births can progress more slowly than the widely accepted benchmark of 1 cm/hour.

According to new data published this week in PLOS Medicine, as part of the World Health Organization's Better Outcomes in Labour Difficulty (BOLD) project, labor progression patterns were examined based on cervical dilatation over time in a cohort of 5,606 women in Nigeria and Uganda. All births were vaginal and there were no adverse outcomes following onset of spontaneous labor.
Researchers found the median time to advance by 1 cm exceeded 1 hour until 5 cm was reached. This was true for women having their first child and women who had given birth previously.

Women giving birth to their first child progressed at the slowest rates (95th percentile) taking up to 7 hours to progress from 4 to 5 cm. Taking over 3 hours to progress from 5 to 6 cm — and up to 9 hours to progress from 6 to 10 cm.

The authors point out that as labor may not naturally accelerate in some women until a cervical dilatation of at least 5 cm, interventions to expedite labor before 5 cm dilatation may be inappropriate — regardless of previous births.
"Our labor progression data clearly demonstrates a minimum cervical dilatation rate of 1cm as 'active phase'. This calculation may be unrealistically fast for some women and should not be universally applied as a threshold for identifying abnormally progressing labor."

"The term 'average labor curves' may not truly reflect all the variability in labor progression. So its use for decision-making in labor management should be de-emphasized.

Olufemi Oladapo MD, World Health Organization (WHO), Department of Reproductive Health and Research, World Bank Special Program of Development and Research Training in Human Reproduction (HRP), Switzerland.


Escalation in the global rates of labor interventions, particularly cesarean section and oxytocin augmentation, has renewed interest in a better understanding of natural labor progression. Methodological advancements in statistical and computational techniques addressing the limitations of pioneer studies have led to novel findings and triggered a re-evaluation of current labor practices. As part of the World Health Organization's Better Outcomes in Labour Difficulty (BOLD) project, which aimed to develop a new labor monitoring-to-action tool, we examined the patterns of labor progression as depicted by cervical dilatation over time in a cohort of women in Nigeria and Uganda who gave birth vaginally following a spontaneous labor onset.

Methods and findings
This was a prospective, multicentre, cohort study of 5,606 women with singleton, vertex, term gestation who presented at <= 6 cm of cervical dilatation following a spontaneous labor onset that resulted in a vaginal birth with no adverse birth outcomes in 13 hospitals across Nigeria and Uganda. We independently applied survival analysis and multistate Markov models to estimate the duration of labor centimetre by centimetre until 10 cm and the cumulative duration of labor from the cervical dilatation at admission through 10 cm. Multistate Markov and nonlinear mixed models were separately used to construct average labor curves. All analyses were conducted according to three parity groups: parity = 0 (n = 2,166), parity = 1 (n = 1,488), and parity = 2+ (n = 1,952). We performed sensitivity analyses to assess the impact of oxytocin augmentation on labor progression by re-examining the progression patterns after excluding women with augmented labors. Labour was augmented with oxytocin in 40% of nulliparous and 28% of multiparous women. The median time to advance by 1 cm exceeded 1 hour until 5 cm was reached in both nulliparous and multiparous women. Based on a 95th percentile threshold, nulliparous women may take up to 7 hours to progress from 4 to 5 cm and over 3 hours to progress from 5 to 6 cm. Median cumulative duration of labor indicates that nulliparous women admitted at 4 cm, 5 cm, and 6 cm reached 10 cm within an expected time frame if the dilatation rate was >= 1 cm/hour, but their corresponding 95th percentiles show that labor could last up to 14, 11, and 9 hours, respectively. Substantial differences exist between actual plots of labor progression of individual women and the ‘average labor curves’ derived from study population-level data. Exclusion of women with augmented labors from the study population resulted in slightly faster labor progression patterns.

Cervical dilatation during labor in the slowest-yet-normal women can progress more slowly than the widely accepted benchmark of 1 cm/hour, irrespective of parity. Interventions to expedite labor to conform to a cervical dilatation threshold of 1 cm/hour may be inappropriate, especially when applied before 5 cm in nulliparous and multiparous women. Averaged labor curves may not truly reflect the variability associated with labor progression, and their use for decision-making in labor management should be de-emphasized.

Olufemi T. Oladapo , Joao Paulo Souza, Bukola Fawole, Kidza Mugerwa, Gleici Perdoná, Domingos Alves, Hayala Souza, Rodrigo Reis, Livia Oliveira-Ciabati, Alexandre Maiorano, Adesina Akintan, Francis E. Alu, Lawal Oyeneyin, Amos Adebayo, Josaphat Byamugisha, Miriam Nakalembe, Hadiza A. Idris, Ola Okike, Fernando Althabe, Vanora Hundley, France Donnay, Robert Pattinson, Harshadkumar C. Sanghvi, Jen E. Jardine, Özge Tunçalp, Joshua P. Vogel, Mary Ellen Stanton, Meghan Bohren, Jun Zhang, Tina Lavender, Jerker Liljestrand, Petra ten Hoope-Bender, Matthews Mathai, Rajiv Bahl and A. Metin Gülmezoglu.

The authors thank A. Iwasaki and C. Dela-Cruz for reagents and advice, A. Mennone Jr. and T. Zhang for assistance with microscopy, C. O’Connor for help with cell sorting and flow cytometry, M. Leblanc and Y.-L. Chang for mouse tissue collection, S. O. Kelley and T. Sack for providing mitochondria-targeted doxorubicin, and N. Varki and the UCSD histopathology core for preparation and analysis of mouse tissues. This work was supported by NIH grant no. R01 AR069876 and the Audrey Geisel Chair in Biomedical Science to G.S.S., NIH grant no. R01 CA216101 to G.S.S and S.M.K., NIH grant no. R35 CA197574 to P.M.G., NIH grant no. R01 CA237586 to Q.Y., NIH grant no. F31 AG062099 to A.G.S. and NIH grant no. P50 CA121974. A.P.W. was supported by grant no. RP170734 from the Cancer Prevention and Research Institute of Texas and grant no. W81XWH-17-1-0052 from the Office of the Assistant Secretary of Defense for Health Affairs, Peer Reviewed Medical Research Program. Z.W. was supported by the China Scholarship Counsel, K.C.M. by the Salk Excellerators Postdoctoral Fellowship and L.E.N. by the George E. Hewitt Foundation for Medical Research Postdoctoral Fellowship.

About the Salk Institute for Biological Studies: Every cure has a starting point. The Salk Institute embodies Jonas Salk's mission to dare to make dreams into reality. Its internationally renowned and award-winning scientists explore the very foundations of life, seeking new understandings in neuroscience, genetics, immunology, plant biology and more. The Institute is an independent nonprofit organization and architectural landmark: small by choice, intimate by nature and fearless in the face of any challenge. Be it cancer or Alzheimer's, aging or diabetes, Salk is where cures begin. Learn more at: salk.edu.

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Dec 24 2019   Fetal Timeline   Maternal Timeline   News 

The authors examined patterns of labor progression over time in a cohort of 5,606 women in Nigeria and Uganda. CREDIT WHO Department of Reproductive Health and Research.

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