Public Release: 

Effectively predicting cesarean delivery in nulliparous women

Study determines a risk score to better inform women of their risk of cesarean delivery

Society for Maternal-Fetal Medicine

ATLANTA (Feb. 1, 2016)--In a study to be presented on Feb. 4 in an oral concurrent session at 1:15 p.m. EST, at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting™, in Atlanta, researchers will present findings from a study titled, How to Predict Cesarean Delivery in the Nulliparous Patient: Results from the Prospective Multi-center Genesis Study. The objective of the Genesis study, was to assess the use of a range of demographic, clinical and ultrasound features to develop a predictive tool for cesarean delivery (CD) in nulliparous, singleton pregnancies.

In contemporary obstetric practice the majority of women now require medical intervention for safe childbirth. Despite all of this obstetric intervention we cannot predict which women will experience the greatest of difficulties during labor. In this study a detailed clinical evaluation and ultrasound assessment were performed after 39 weeks' gestation. Women and their managing clinicians were blinded to the ultrasound derived fetal biometry. This study developed a risk scoring tool based on five easy to record parameters, which accurately predicts an individual woman's risk of CD.

Of 2,336 women recruited to the Genesis Study, 491 (21%) had an unplanned cesarean delivery. In a multivariate analysis, five parameters were determined to be the best combined predictors of CD. These were advancing maternal age, short maternal height, higher body mass index, a larger fetal abdominal circumference and increasing fetal head circumference. The study's conclusion was that, by using these five factors, overall risk of CD in nulliparous women at term can be better determined.

Naomi Burke, M.D. lead researcher on the Genesis Study stated "We developed a simple risk scoring system for cesarean delivery in first time mothers. We hope this will aid women and obstetricians with decisions about labor and delivery". Burke will present the findings at the SMFM annual meeting.

Fergal Malone, chairman of the Perinatal Ireland Research Consortium commented, "This risk assessment tool may be useful for planning service needs as well as for individual patient's decisions on place and mode of delivery."

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A copy of the abstract is available at http://www.smfmnewsroom.org and below. For interviews please contact Vicki Bendure at Vicki@bendurepr.com 202-374-9259 (cell).

The Society for Maternal-Fetal Medicine (est. 1977) is the premiere membership organization for obstetricians/gynecologists who have additional formal education and training in maternal-fetal medicine. The society is devoted to reducing high-risk pregnancy complications by sharing expertise through continuing education to its 2,000 members on the latest pregnancy assessment and treatment methods. It also serves as an advocate for improving public policy, and expanding research funding and opportunities for maternal-fetal medicine. The group hosts an annual meeting in which groundbreaking new ideas and research in the area of maternal-fetal medicine are shared and discussed. For more information visit http://www.smfm.org.

Abstract 20: How to Predict Cesarean Delivery in the Nulliparous Patient: Results from the Prospective Multi-center Genesis Study

Authors: Naomi Burke1, Gerry Burke2, Fionnuala Breathnach1, Fionnuala McAuliffe3, John J. Morrison4, Michael Turner5, Samina Dornan6, John Higgins7, Amanda Cotter2, Michael Geary8, Fiona Cody9, Peter McParland10, Sean Daly11, Patrick Dicker12, Elizabeth Tully1, Fergal D. Malone1
1Obstetrics and Gynecology, Royal College of Surgeons in Ireland, Dublin, Ireland, 2Obstetrics and Gynecology, Graduate Entry Medical School, University of Limerick, Limerick, Ireland, 3Obstetrics and Gynecology, UCD School of Medicine and Medical Science, National Maternity Hospital, Dublin, Ireland, 4Obstetrics and Gynecology, National University of Ireland, Galway, Ireland, 5Obstetrics and Gynecology, UCD Centre for Human Reproduction Coombe Women and Infants University Hospital, Dublin, Ireland, 6Obstetrics and Gynecology, Royal Jubilee Maternity Hospital, Belfast, Ireland, 7Obstetrics and Gynecology, University College Cork, Cork University Maternity Hospital, Cork, Ireland, 8Obstetrics and Gynecology, St Michael's Hospital, University of Toronto, Toronto, ON, Canada, 9Obstetrics and Gynecology, Rotunda Hospital, Dublin, Ireland, 10Obstetrics and Gynecology, National Maternity Hospital, Dublin, Ireland, 11Obstetrics and Gynecology, Coombe Women and Infants University Hospital, Dublin, Ireland, 12Epidemiology and Public Health, Royal College of Surgeons in Ireland, Dublin, Ireland

Objective: The rising cesarean delivery rate continues to generate concern. While many studies have tried to predict cesarean delivery (CD) by prenatal diagnosis of cephalopelvic disproportion or fetal macrosomia, neither strategy has proved particularly useful in the clinical setting. In this primary analysis of the Genesis Study we sought to prospectively assess the use of a range of demographic, clinical and ultrasound features to develop a predictive tool for CD in nulliparous, singleton pregnancies.

Study Design: The Genesis Study recruited 2,336 nulliparous patients with a vertex presentation between 39+0 and 40+6 weeks' gestation in a prospective multi-center national study to examine predictors of CD. At recruitment a detailed clinical evaluation and ultrasound assessment were performed. Patients and their managing clinicians were blinded to the ultrasound details, to reduce bias from knowledge of this data potentially influencing mode of delivery. All hypothetical prenatal risk factors for unplanned CD were assessed individually and as a composite to eliminate confounding factors. Multiple logistic regression analysis was used to develop a risk evaluation tool for CD in nulliparous patients.

Results: From a cohort of 2,336 nulliparous patients, 491 (21%) had an unplanned CD. In a multivariate analysis, five parameters (maternal age, maternal height, BMI, fetal AC and fetal HC) were determined to be the best combined predictors of CD. These five parameters are listed in Table 1 along with their respective odds ratios when calculated at different time points during pregnancy. Individual Z scores were calculated for demographic and biometric data to determine these odds ratios and a risk score. Z scores can be calculated from Table 1. The totaled Z scores for the five parameters can then be applied to Figure 1 to give a personalized risk of CD.

Conclusion: Five parameters (maternal age, BMI, height, fetal AC and fetal HC) can be used to better determine the overall risk of cesarean delivery in nulliparous patients at term. A risk score can be used to better inform patients of their individualized risk of CD in early gestation and again from 39 weeks' gestation. This risk tool may be useful for planning service needs as well as for individual patient's decisions on place and mode of delivery.

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