1039: Determining the risk of cesarean delivery in the nulliparous population stratified by age and BMI

Abstract

The rising cesarean delivery (CD) rate is a complex issue, particularly in a nulliparous population of advancing maternal age and increasing body mass index (BMI). The objective of this study was to stratify the CD rate in nulliparous women by age and BMI to determine if there was any significant difference within this cohort. This was a retrospective review of CD procedures of nulliparous women in Galway University Hospital, Galway and The Rotunda Hospital, Dublin, Ireland, over 4 years (from 2014 through 2017), with Institutional Review board approval from both hospitals. Data were obtained from hospital databases including details on mode of delivery, maternal age and BMI. The number of CD procedures and percentage was determined for each age and BMI category and graphed for analysis. Statistical analysis was performed using SPSS software. Sub-analysis was performed on nulliparous women in spontaneous labor (Robson Group 1). A total of n=17,474 nulliparous women were included for analysis. N=6,257 (35.8%) had CD procedures. Results are presented in Table 1. A trend can be seen emerging showing increasing CD rates for increasing age and BMI categories. Women under 20 years with a BMI of < 18.5kg/m2 had a CD rate of 9%, while those with a BMI of 30-34.9kg/m2 had a 29% CD rate. Women 35-39 years of BMI < 18.5 kg/m2 and 30-34.9kg/m2 had CD rates of 36% and 62% respectively. For women over 45 years the CD rates ranged from 80-100% in all BMI groups. The higher CD rates in women of higher BMI and advanced maternal age when compared with younger women of lower BMI was significant (P< 0.05). Similar results were obtained when analyzing the CD rates of women in Robson Group 1. We observed significant differences within the nulliparous population in the CD rates when stratified by age and BMI. The development of customized charts subdivided by age and BMI may aide to more accurately estimate a women’s risk of CD In a first pregnancy, provide a useful counseling tool to women and their clinicians and may also assist in the comparison of CD rates between obstetric units.