Prediction of vaginal birth after cesarean in China

OBJECTIVE

This study aimed to develop and validate a prediction model of vaginal birth after cesarean delivery (VBAC) in China.

METHODS

A nomogram for effective prediction of VBAC of singleton, cephalic and one previous low-transverse cesarean section deliveries was created by comparing the combinations of ultrasonographic and non-ultrasonographic factors from five hospitals between 2018 and 2019.

RESULTS

A total of 1066 women were included. Of the women who underwent trial of labor after cesarean (TOLAC), 854 (80.1%) had a VBAC. Ultrasound factors included reached a higher area under the curve (AUC) combined with non-ultrasonographic factors. Of the three ultrasonographic factors analyzed, the best predictive factor for successful TOLAC was fetal abdominal circumference. A nomogram was generated with eight validated factors, including maternal age, gestational week, height, previous vaginal delivery, Bishop score, dilatation of the cervix at the time of admission, body mass index at delivery, and fetal abdominal circumference by ultrasound. The trained and validated AUC were 0.719 (95% confident interval 0.674-0.764) and 0.774 (95% confident interval 0.712-0.837), respectively.

CONCLUSION

Our VBAC nomogram based on obstetric factors and fetal abdominal circumference obtained by ultrasound could be used to counsel women who are considering TOLAC.

Risk Factors for Intrapartum Cesarean Section Delivery in Low-risk Multiparous Women Following at Least a Prior Vaginal Birth (Robson Classification 3 and 4)

OBJECTIVE

 The aim of the present study was to evaluate the risk factors for cesarean section (C-section) in low-risk multiparous women with a history of vaginal birth.

METHODS

 The present retrospective study included low-risk multiparous women with a history of vaginal birth who gave birth at between 37 and 42 gestational weeks. The subjects were divided into 2 groups according to the mode of delivery, as C-section Group and vaginal delivery Group. Risk factors for C-section such as demographic characteristics, ultrasonographic measurements, smoking, weight gain during pregnancy (WGDP), interval time between prior birth, history of macrosomic birth, and cervical dilatation at the admission to the hospital were obtained from the charts of the patients. Obstetric and neonatal outcomes were compared between groups.

RESULTS

 The most common C-section indications were fetal distress and macrosomia (33.9% [n = 77 and 20.7% [n = 47] respectively). A bivariate correlation analysis demonstrated that mothers aged > 30 years old (odds ratio [OR]: 2.09; 95% confidence interval [CI]: 1.30-3.34; p = 0.002), parity >1 (OR: 1.81; 95%CI: 1.18-2.71; p = 0.006), fetal abdominal circumference (FAC) measurement > 360 mm (OR: 34.20; 95%CI: 8.04-145.56; p < 0.001)) and < 345 mm (OR: 3.06; 95%CI: 1.88-5; p < 0.001), presence of large for gestational age (LGA) fetus (OR: 5.09; 95%CI: 1.35-19.21; p = 0.016), premature rupture of membranes (PROM) (OR: 1.52; 95%CI: 1-2.33; p = 0.041), and cervical dilatation < 5cm at admission (OR: 2.12; 95%CI: 1.34-3.34; p = 0.001) were associated with the group requiring a C-section.

CONCLUSION

 This is the first study evaluating the risk factors for C-section in low-risk multiparous women with a history of vaginal birth according to the Robson classification 3 and 4. Fetal distress and suspected fetal macrosomia constituted most of the C-section indications.

Impact of biometric measurement error on identification of small- and large-for-gestational-age fetuses

OBJECTIVES

First, to obtain measurement-error models for biometric measurements of fetal abdominal circumference (AC), head circumference (HC) and femur length (FL), and, second, to examine the impact of biometric measurement error on sonographic estimated fetal weight (EFW) and its effect on the prediction of small- (SGA) and large- (LGA) for-gestational-age fetuses with EFW < 10^th and > 90^th percentile, respectively.

METHODS

Measurement error standard deviations for fetal AC, HC and FL were obtained from a previous large study on fetal biometry utilizing a standardized measurement protocol and both qualitative and quantitative quality-control monitoring. Typical combinations of AC, HC and FL that gave EFW on the 10^th and 90^th percentiles were determined. A Monte-Carlo simulation study was carried out to examine the effect of measurement error on the classification of fetuses as having EFW above or below the 10^th and 90^th percentiles.

RESULTS

Errors were assumed to follow a Gaussian distribution with a mean of 0 mm and SDs, obtained from a previous well-conducted study, of 6.93 mm for AC, 5.15 mm for HC and 1.38 mm for FL. Assuming errors according to such distributions, when the 10^th and 90^th percentiles are used to screen for SGA and LGA fetuses, respectively, the detection rates would be 78.0% at false-positive rates of 4.7%. If the cut-offs were relaxed to the 30^th and 70^th percentiles, the detection rates would increase to 98.2%, but at false-positive rates of 24.2%. Assuming half of the spread in the error distribution, using the 10^th and 90^th percentiles to screen for SGA and LGA fetuses, respectively, the detection rates would be 86.6% at false-positive rates of 2.3%. If the cut-offs were relaxed to the 15^th and 85^th percentiles, respectively, the detection rates would increase to 97.0% and the false-positive rates would increase to 6.3%.

CONCLUSIONS

Measurement error in fetal biometry causes substantial error in EFW, resulting in misclassification of SGA and LGA fetuses. The extent to which improvement can be achieved through effective quality assurance remains to be seen but, as a first step, it is important for practitioners to understand how biometric measurement error impacts the prediction of SGA and LGA fetuses. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Defining fetal growth restriction: abdominal circumference as an alternative criterion

PURPOSE

The purpose of this study is to determine if using abdominal circumference percentile (AC) to define fetal growth restriction (FGR) improves ultrasound at ≥36 weeks as a screening test for small for gestational age (SGA).

MATERIALS AND METHODS

All non-anomalous singletons undergoing ultrasound at a single center at ≥36 weeks during 12/2008-5/2014 were included. FGR was defined as (estimated fetal weight) estimated fetal weight (EFW) and/or abdominal circumference (AC) < 10 for gestational age (GA). The primary outcome was SGA (birthweight ≤10th percentile for GA). Data were stratified by maternal race/ethnicity and BMI. Sensitivity, specificity, false-positive rate (FPR), positive- and negative-predictive values (positive-predictive value (PPV), negative-predictive value (NPV)), and areas under the receiver-operating characteristic (ROC) curve (AUC were calculated.

RESULTS

There were 1594 ultrasounds. Median (IQR) ultrasound GA was 37.3 (36.6-38.0), days to delivery 10.6 (5.0-18.4), and delivery GA 39.29 (38.6-39.9). EFW <10 had the following characteristics: sensitivity 50.6%, FPR 2.0%, PPV 83.8%, and AUC 0.743. Using AC <10, these were 64.0, 2.9, 81.3, and 0.806, respectively. Using AC or EFW <10, these were 67.5, 3.3, 80.3, and 0.821, respectively; this criterion has the largest AUC (p < .008). This finding persisted when stratified by maternal race/ethnicity and BMI.

CONCLUSIONS

AC <10 is more sensitive and has a similar PPV compared with EFW <10 for SGA. Using AC <10 or EFW <10 has the best balance of sensitivity and specificity as a screening test and has a low FPR. AC may be a reasonable alternative criterion to EFW for FGR diagnosis.

Translation of fetal abdominal circumference-guided therapy of gestational diabetes complicated by maternal obesity to a clinical outpatient setting

OBJECTIVE

To evaluate the effectiveness of fetal abdominal circumference-guided therapy for gestational diabetes (GDM) in an outpatient population characterized by highly-prevalent maternal obesity.

METHODS

Data for this translational retrospective cohort study come from medical records. Fetal abdominal circumference was assessed by ultrasound in late second trimester, and sex- and gestational age-specific percentiles assigned. Taking fetal abdominal circumference percentile as a marker for adequacy of fetal growth, maternal glucose targets were set accordingly: loose, moderate or tight. Associations between mother's targets and neonatal outcomes (small for gestational age (SGA), large for gestational age (LGA), macrosomia, neonatal intensive care unit (NICU) admission, and neonatal hypoglycemia) were assessed using unconditional logistic regression, controlling for pre-gravid body mass index (BMI) and gestational weight gain.

RESULTS

In 419 consecutive pregnancies complicated by GDM, neonatal outcomes compared favorably with previous randomized trials of intensive GDM management. Importantly, adverse outcomes were observed less often than might be expected in an obese GDM population. BMI did not have an independent effect on neonatal outcomes.

CONCLUSIONS

Ultrasound-guided therapy of GDM, in general clinic use, can limit excess macrosomia and LGA, even in a population with significant maternal obesity.

Glycemic control and fetal abdominal circumference

Aim:

To study about the correlation between the glycemic status and increase in fetal abdominal circumference in gestational diabetes patients and its relationship with fetal birth weight.

Materials and Methods:

Seventy-five gestational diabetes mellitus (GDM) patients were taken up for study with duly informed consent and suggested for anthropometry profile and glycemic profile with HbA1C. Fetal abdominal circumference was measured during routine scans. The patients were followed up till delivery and the fetal birth was noted.

Inclusion Criteria:

Seventy-five gestational diabetic mothers who have attended a secondary level diabetic clinic and on regular follow-up were included in the study.

Exclusion Criteria:

Pre-GDM mothers, patients with co-morbid disease were excluded from the study.

Expected Results:

Fetal abdominal circumference correlated well with fluctuating glycemic control and fetal birth weight.