In the past half century, labor and delivery practice has followed the Friedman curve in the United States. However, the obstetric population and labor management have changed substantially during the same period. Mounting evidence has begun to suggest that the Friedman curve may no longer be appropriate for contemporary labor practice. New, evidence-based definitions of labor protraction and arrest are needed. In addition, our understanding of the reasons behind the rising cesarean section rate was incomplete because detailed information on labor and delivery was lacking at a national level. The primary goals of this observational study were:
- Explore the underlying causes of the high cesarean rate in the U.S. population;
- Describe contemporary labor progression at the national level; and
- Determine when is the more appropriate time to perform a Cesarean delivery in women with labor protraction and arrest.
The CSL collected detailed information from electronic medical records in 228,562 deliveries from 19 hospitals across the U.S. from 2002 to 2008. The most common reason for cesarean section was elective repeat cesarean delivery due to a previous uterine scar, accounting for approximately one third of all cesarean deliveries. However, investigators also found that one out of three first time mothers delivered by cesarean section and a high percentage of intrapartum cesarean deliveries were performed too soon before women achieved active labor. These findings mean that preventing cesarean delivery in the first pregnancy will go a long way to decrease the national cesarean delivery rate. In another major study from the CSL, labor patterns were found to be different for individual women. Many parturients did not have a clear pattern of active phase, and more importantly, the active phase of labor may not start until 6 cm of cervical dilation or later. This finding differs from the prevailing concepts established by the Friedman curve which illustrated that the active phase starts before 4 cm dilation. Researchers have also compared the differences in labor patterns using data from the CSL of women who presented in labor for delivery and compared them to women from the Collaborative Perinatal Project, another NIH sponsored study from the late 1950's to early 1960s. Labor patterns were found to be longer now than approximately 50 years ago. Researchers have also examined other factors that may affect labor progression and cesarean delivery, such as induction of labor, maternal obesity, and epidural analgesia for labor pain. Other areas of ongoing research include determining the optimal time for second stage of labor, when pushing begins, and exploring how the sociodemographic changes in the current obstetrical population have affected pregnancy complications, maternal and neonatal morbidity, and implications for clinical management including delivery timing and route. Researchers are exploring how chronic diseases such as hypertension, diabetes and asthma also affect these outcomes. Further work from the CSL study will help shape the future clinical care of pregnant women.
- CSL Papers and Presentations (PDF - 483 KB)
- Zhen Chen, Ph.D.
- Stefanie Hinkle, Ph.D.
- Pauline Mendola, Ph.D.
- Lindsey Sjaarda, Ph.D.
- Cuilin Zhang, M.D., M.P.H., Ph.D.
- Rajeshwari Sundaram, M.S., Ph.D.
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- Grantz KL, Sundaram R, Ma L, Hinkle S, Berghella V, Hoffman MK, Reddy UM. Reassessing the Duration of the Second Stage of Labor in Relation to Maternal and Neonatal Morbidity. Obstetrics and Gynecology. 2018; 131(2):345-353. PMID: 29324600. PMCID: PMC5785437
- Kim SS, Zhu Y, Grantz KL, Hinkle SN, Chen Z, Wallace ME, Smarr MM, Epps NM, Mendola P. Obstetric and Neonatal Risks Among Obese Women Without Chronic Disease. Obstetrics and Gynecology. 2016; 128(1):104-112. PMID: 27275800. PMCID: PMC4917420
- Grantz KL, Gonzalez-Quintero V, Troendle J, Reddy UM, Hinkle SN, Kominiarek MA, Zhang J. Labor Patterns in Women Attempting Vaginal Birth After Cesarean with Normal Neonatal Outcomes. American Journal of Obstetrics and Gynecology. 2015; 213(2):226.e1-6. PMID: 25935774. PMCID: PMC4519387
- Mendola P, Mumford SL, Mӓnnistӧ TI, Holston A, Reddy UM, Laughon SK. Controlled Direct Effects of Preeclampsia on Neonatal Health After Accounting for Mediation by Preterm Birth. Epidemiology. 2015; 26(1):17-26. PMID: 25437315
- Parikh LI, Reddy UM, Männistö T, Mendola P, Sjaarda L, Hinkle S, Lu Z, Laughon SK. Neonatal outcomes in early term birth. American Journal of Obstetrics and Gynecology. 2014; 211(3):265.e1-265.e11. PMID: 24631438. PMCID: PMC4149822
- Mendola P, Männistö TI, Leishear K, Reddy UM, Chen Z, Laughon SK. Neonatal health of infants born to mothers with asthma. The Journal of Allergy and Clinical Immunology. 2014; 133(1):85-90.e1-4. PMID: 23916153. PMCID: PMC3874245
- Laughon SK, Berghella V, Reddy UM, Sundaram R, Lu Z, Hoffman MK. Neonatal and maternal outcomes with prolonged second stage of labor. Obstetrics and Gynecology. 2014; 124(1):57-67. PMID: 24901265. PMCID: PMC4065200
- Mendola P, Laughon SK, Männistö TI, Leishear K, Reddy UM, Chen Z, Zhang J. Obstetric complications among US women with asthma. American Journal of Obstetrics and Gynecology. 2013; 208:127.e1-8. PMID: 23159695. PMCID: PMC3557554
- Männistö T, Mendola P, Reddy U, Laughon SK. Neonatal outcomes and birth weight in pregnancies complicated by maternal thyroid disease. American Journal of Epidemiology. 2013; 178(5):731-740. PMID: 23666815. PMCID: PMC3755642
- Männistö T, Mendola P, Grewal J, Xie Y, Chen Z, Laughon SK. Thyroid diseases and adverse pregnancy outcomes in a contemporary US cohort. The Journal of Clinical Endocrinology and Metabolism. 2013; 98(7):2725-2733. PMID: 23744409. PMCID: PMC3701274
- Werder E, Mendola P, Männistö T, O'Loughlin J, Laughon SK. Effect of maternal chronic disease on obstetric complications in twin pregnancies in a United States cohort. Fertility and Sterility. 2013; 100(1):142-149.e1-2. PMID: 23541402. PMCID: PMC3699962
- Bowers K, Laughon SK, Kim S, Mumford SL, Brite J, Kiely M, Zhang C. The association between a medical history of depression and gestational diabetes in a large multi-ethnic cohort in the United States. Paediatric and Perinatal Epidemiology. 2013; 27(4):323-328. PMID: 23772933. PMCID: PMC4123954
- Bowers K, Laughon SK, Kiely M, Brite J, Zhang C. Gestational diabetes, pre-pregnancy obesity and pregnancy weight gain in relation to excess fetal growth: variations by race/ethnicity. Diabetologia 2013; 56(6):1263-1271. PMID: 23571827
- Reddy UM, Zhang J, Sun L, Chen Z, Raju TN, Laughon SK. Neonatal mortality by attempted route of delivery in early preterm birth. American Journal of Obstetrics and Gynecology. 2012; 207(2):117.e1-8. PMID: 22840720. PMCID: PMC3408612
- Laughon SK, Zhang J, Grewal J, Sundaram R, Beaver J, Reddy UM. Induction of labor in a contemporary obstetric cohort. American Journal of Obstetrics and Gynecology. 2012; 206(6):486.e1-9. PMID: 22520652. PMCID: PMC3361637
- Laughon SK, Branch DW, Beaver J, Zhang J. Changes in labor patterns over 50 years. American Journal of Obstetrics & Gynecology. 2012; 206(5):419.e1-9. PMID: 22542117. PMCID: PMC3655692