Association of Recorded Estimated Fetal Weight and Cesarean Delivery in Attempted Vaginal Delivery at Term

Abstract

Objective To evaluate the association between documentation of estimated fetal weight, and its value, with cesarean delivery. Methods This was a secondary analysis of a multi-center observational cohort of 115,502 deliveries from 2008 to 2011. Data were abstracted by trained and certified study personnel. We included women ≥37 weeks attempting vaginal delivery with live, non-anomalous, singleton, vertex fetuses, and no history of cesarean delivery. Rates and odds ratios were calculated for women with ultrasound or clinical estimated fetal weight, compared to women without documentation of estimated fetal weight. Further subgroup analyses were performed for estimated fetal weight categories (<3,500, 3,500 to 3,999, and ≥4,000 grams) stratified by diabetic status. Multivariable analyses were performed to adjust for important potential confounding variables. Results We included 64,030 women. Cesarean delivery rates were 18.5% in the ultrasound estimated fetal weight (EFW) group, 13.4% in the clinical EFW group, and 11.7% in the no documented EFW group (p < 0.001). After adjustment (including for birth weight), the adjusted OR (aOR) of cesarean delivery was 1.44 (95% CI 1.31–1.58, p<0.001) for women with ultrasound EFW and 1.08 for clinical EFW (95% CI 1.01–1.15, p=0.017), compared to women with no documented EFW (referent). The highest estimates of fetal weight conveyed the greatest odds of cesarean delivery. When ultrasound EFW was ≥4,000 grams, the aOR was 2.15 (95% CI 1.55–2.98, p<0.001) in women without diabetes, and 9.00 (95% CI 3.65–22.17, p<0.001) in women with diabetes, compared to those with EFW <3,500 grams. Conclusion In this contemporary cohort of women attempting vaginal delivery at term, documentation of estimated fetal weight (obtained clinically or, particularly, by ultrasound) was associated with increased odds of cesarean delivery. This relationship was strongest at higher fetal weight estimates, even after controlling for the effects of birth weight and other factors associated with increased cesarean delivery risk.

Accuracy of immediate antepartum ultrasound estimated fetal weight and its impact on mode of delivery and outcome - a cohort analysis

“…In a retrospective cohort analysis, EFW was also associated with an increased risk for caesarean delivery (OR 1.44, 95% CI 1.1–1.9) [ 20 ]. Similar results were found in a recently published big cohort study of 64,030 women at term who attempted vaginal delivery [ 21 ]. In this study the knowledge of EFW was significantly associated with an increased risk of caesarean delivery (adjusted OR 1.44 (95% CI 1.31–1.58, P < 0.001).…”

Does maternity care decision‐making conform to shared decision‐ making standards for repeat cesarean and labor induction after suspected macrosomia?

“…In the case of suspected fetal macrosomia, systematic reviews have clarified that estimates of fetal weight are imprecise and frequently falsely identify large fetuses, and that induced labor for suspected fetal macrosomia does not improve outcomes . Furthermore, this practice has been associated with higher rates of cesareans . For these reasons, a long‐standing Practice Bulletin of the American College of Obstetricians and Gynecologists (ACOG), which was in effect when our survey participants gave birth and has recently been reaffirmed (2015), clarifies that suspected fetal macrosomia is not an indication for labor induction .…”

Are selection criteria for healthy pregnancies responsible for the gap between fetal growth in the French national Elfe birth cohort and the Intergrowth‐21st fetal growth standards?

“…The IG standards would also classify more fetuses as LGA which could lead to unnecessary surveillance of these fetuses and possibly iatrogenic interventions, such as earlier delivery or caesarean. 32 Our finding that the differences in growth parameters between the sample restricted to women fulfilling the IG selection criteria and the overall population were very small is relevant for the current debate on growth standards vs. references. It shows that population selection is not an explanation for the differences between the IG standards and fetal growth in the ELFE cohort and is also unlikely to explain the differences found in other population-based studies.…”

“…requiring more surveillance because of potentially suboptimal growth; many professional societies recommend that monitoring small for gestational age (SGA) fetuses 1-3 and identifying large for gestational age fetuses are important for the surveillance of women with gestational diabetes and for the management of delivery. [29][30][31][32] Several studies have shown that failure to detect growth restriction among SGA fetuses is associated with higher rates of stillbirths and neonatal morbidity. [33][34][35] The IG standards would classify fewer fetuses as being SGA than the currently used references and could worsen performance, already judged to be sub-optimal, 29 for identifying SGA fetuses needing more surveillance.…”