Related Experiment Video
Updated: May 22, 2026

Electromyometrial Imaging of Uterine Contractions in Pregnant Women
Published on: May 26, 2023
Changes in labor patterns over 50 years
S Katherine Laughon1, D Ware Branch, Julie Beaver
1Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA.
Objective:
The objective of the study was to examine differences in labor patterns in a modern cohort compared with the 1960s in the United States.
Study Design:
Data from pregnancies at term, in spontaneous labor, with cephalic, singleton fetuses were compared between the Collaborative Perinatal Project (CPP, n = 39,491 delivering 1959-1966) and the Consortium on Safe Labor (CSL; n = 98,359 delivering 2002-2008).
Results:
Compared with the CPP, women in the CSL were older (26.8 ± 6.0 vs 24.1 ± 6.0 years), heavier (body mass index 29.9 ± 5.0 vs 26.3 ± 4.1 kg/m(2)), had higher epidural (55% vs 4%) and oxytocin use (31% vs 12%), and cesarean delivery (12% vs 3%). First stage of labor in the CSL was longer by a median of 2.6 hours in nulliparas and 2.0 hours in multiparas, even after adjusting for maternal and pregnancy characteristics, suggesting that the prolonged labor is mostly due to changes in practice patterns.
Conclusion:
Labor is longer in the modern obstetrical cohort. The benefit of extensive interventions needs further evaluation.
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