Attributable factors for the rising cesarean delivery rate over three decades: an observational cohort study

BACKGROUND

Cesarean delivery rates continue to rise globally the reasons for which are incompletely understood.

OBJECTIVES

We aimed to characterize attributable factors for increasing cesarean delivery rates over a 30-year period within our health network.

STUDY DESIGN

This was a planned observational cohort study across two hospitals (a large tertiary referral hospital and a metropolitan hospital) in Sydney, Australia using data from a previously published study. Two time periods were compared: 1989-1999 and 2009-2016, between which the cesarean delivery rate increased from 19% to 30%. Participants were all women who had a cesarean delivery after 24 weeks gestational age. Data were analyzed using multiple imputation and robust Poisson regression to calculate differences in the adjusted and unadjusted relative risk of cesarean delivery and estimate the changes in the cesarean delivery rate attributable to maternal and clinical factors. The primary outcome was cesarean delivery.

RESULTS

After 576 exclusions, 102 589 births were included in the analysis. Fifty-six percent of the increase in the rate of cesarean delivery was attributed to changes in the distribution of maternal age, body mass index, parity and history of previous cesarean delivery. An additional 10% of the increase was attributed to changes in the obstetric management of the following high-risk pregnancies: multiple gestation, malpresentation (mainly breech) and preterm singleton birth. When pre-labor cesarean deliveries for maternal choice, suspected fetal compromise, previous pregnancy issues and suspected large fetus were excluded, 78% of the increase was attributed to either maternal factors or changes in the obstetric management of these high-risk pregnancies.

CONCLUSIONS

Most of the steep rise in the cesarean delivery rate from 19% to 30% was attributed to changes in maternal demographic and clinical factors. This observation is relevant to developing preventative strategies which account for nulliparity, age, body mass index, and the management of high-risk pregnancies.

TWEETABLE ABSTRACT

More than half of the increase in the rate of cesarean delivery is attributable to changes in maternal age, BMI, parity and history of cesarean delivery.

Combining early (<11 weeks' gestation) ultrasound features and maternal factors to predict small-for-gestational age neonates

Objectives

Placental related adverse pregnancy outcomes such as fetal growth restriction have significant short- and long-term implications for both mother and fetus. This study aimed to determine if conventional and novel early first trimester ultrasound measures are associated with small for gestational age (SGA) neonates. In addition, we aimed to assess whether a combination of ultrasound measures, maternal characteristics and biochemistry improved the prediction of this adverse pregnancy outcome.

Methods

This was a prospective cohort study including ultrasound measurements: trophoblast thickness (TT), trophoblast volume (TV), mean uterine artery pulsatility index, crown-rump length, fetal heart rate, mean sac diameter (MSD) and yolk sac diameter. Biochemical markers considered in the analysis were placental growth factor (PIGF), pregnancy - associated plasma protein A (PAPP-A), beta human chorionic gonadotropin and alpha fetoprotein. Regression models were fitted for ultrasound parameters using multiples of the median (MoM). All measures were compared with normal birthweight (BW) ≥10^th centile and SGA (BW < 10^th centile). Logistic regression analysis was used to create a clinical prediction model for SGA based on maternal characteristics, ultrasound measurements at <11 weeks gestational age and maternal biochemistry collected at 10-14 weeks.

Results

As compared to pregnancies delivered of babies with normal BW (n = 1068), MoM values for TT, TV, MSD, PAPP-A and PIGF were significantly reduced (P < 0.05) in pregnancies delivered of SGA babies (n = 73). The proposed logistic regression model includes maternal height, TV and PIGF resulting in an area under the receiver operator curve 0.70 (95% CI 0.63-0.76) for the prediction of SGA.

Conclusion

A significantly decreased TV, measured <11 weeks gestation, is predictive of BW < 10^th centile. With addition of maternal height and PIGF, this three-marker algorithm provided a reasonable predictive value for the development of SGA later in pregnancy.

Uterine Artery Pulsatility Index Assessment at <11 Weeks' Gestation: A Prospective Study

OBJECTIVE

Mean uterine artery pulsatility index (meanUAPI) is commonly measured at 11-13+6 weeks to predict adverse pregnancy outcomes including hypertensive disorders and small-for-gestational age. The aims of this study were to establish a population-specific reference range for meanUAPI at <11 weeks, to determine if an abnormal meanUAPI at <11 weeks was associated with adverse pregnancy outcome, and to assess changes in meanUAPI between <11 weeks and 11-13+6 weeks.

METHODS

A prospective cohort was examined at <11 weeks and at 11-13+6 weeks to develop reference ranges for meanUAPI. Based on these regression models, meanUAPI Z-scores were compared between outcome groups using a two-sample t test. Longitudinal changes in the meanUAPI between <11 and 11-13+6 weeks were assessed by two-way mixed ANOVA.

RESULTS

Prior to 11 weeks, there was no significant difference in meanUAPI between normal (n = 622) and adverse (n = 80) outcomes (mean [95% CI]: 2.62 [2.57-2.67] and 2.67 [2.50-2.84], respectively; p = 0.807). At 11-13+6 weeks, meanUAPI was significantly higher in the adverse (n = 66) compared with the normal (n = 535) outcome group (mean [95% CI]: 1.87 [1.70-2.03] and 1.67 [1.63-1.72], respectively; p = 0.040). There was a statistically significant decrease (p < 0.0001) in meanUAPI between the two time points.

CONCLUSION

MeanUAPI measured at <11 weeks' gestation does not appear to be a useful marker for the prediction of placental-related adverse pregnancy outcomes, supporting an argument for the prediction of risk at 11-13+6 weeks' gestation.

First-trimester ultrasound features associated with subsequent miscarriage: A prospective study

BACKGROUND

First-trimester miscarriage is common, with women increasingly offered an ultrasound scan early in the first trimester to assess the status of their pregnancy. Ultrasound is uniquely situated to significantly impact the clinical management of these women.

AIMS

This study aims to determine whether there were any differences in the early ultrasound appearances of pregnancies that continued to be viable or resulted in miscarriage before 12 weeks gestation.

MATERIALS AND METHODS

This was a prospective cohort study including ultrasound measurements: mean sac diameter (MSD), yolk sac diameter (YSD), crown-rump length (CRL), fetal heart rate (FHR), trophoblast thickness, trophoblast volume (TTV) and mean uterine artery pulsatility index (meanUAPI). Regression models were fitted for each parameter and Z-scores compared between cohorts that progressed or miscarried after the scan but before 12 weeks gestation. Logistic regression analysis was used to create a prediction model for miscarriage prior to 12 weeks gestation based on the standardised ultrasound measurements recorded during the early first-trimester scan.

RESULTS

Comparison of Z-Scores for meanUAPI, TTV, FHR and MSD demonstrated significant variation between the two groups. The proposed logistic regression model resulted in an area under the receiver operator curve of 0.81. At a false-positive rate of 30%, the model resulted in a sensitivity of 76% (95% CI 64-89%).

CONCLUSION

The combination of FHR, meanUAPI, TTV in a prediction model for miscarriage may prove to be of value for ongoing pregnancy management in the first trimester.

Is ultrasound measured fetal biometry predictive of intrapartum caesarean section for failure to progress?

BACKGROUND

There are global concerns regarding excessive caesarean rates, which could be reduced by identification of risk factors leading to preventative measures such as induction of labour.

AIMS

This study aims to describe the association between antenatal ultrasound and emergency caesarean section for: (i) failure to progress; (ii) other indications; and (iii) any indication.

MATERIALS AND METHODS

Women who had an ultrasound in pregnancy between 36^(+0/7) to 38^(+6/7) weeks at Royal Prince Alfred Hospital from January 2005 to June 2009 were included. Ultrasound parameters were linked to clinical parameters from the maternity database. Missing clinical data were imputed and multiple logistic regression performed.

RESULTS

Fetal biometry data were available for 2006 pregnancies. After adjusting for maternal age, height, body mass index, parity, previous caesarean section and diabetes, caesarean section for failure to progress was associated with estimated fetal weight (odds ratio (OR) 2.24 (95% CI: 1.76-2.84) per 500 g increase); or biparietal diameter (OR 1.51 (1.16-1.97) per 5 mm increase) and abdominal circumference (OR for the 4th quartile (>75th centile) compared with the 10-25th centile group was 2.09 (1.13-3.85)).* There were also non-linear associations between components of fetal biometry and caesarean section for fetal distress and for any indication.

CONCLUSIONS

Components of fetal biometry in the third trimester are associated with intrapartum caesarean section for failure to progress. These parameters could be incorporated into models to predict emergency caesarean section which could lead to implementation of preventative strategies. *[Corrections added on 29 January 2018, after first online publication, '(OR for the 4th quartile (>7th centile)' has been changed to '(OR for the 4th quartile (>75th centile)'.].

Use of the CryoPredict algorithm to predict live birth from cryopreserved embryos

BACKGROUND

Currently, the viability of cryostored blastocysts that are subsequently re-warmed is determined via the percentage of cell survival. However, the large number of cells that forms the blastocyst can make this estimate difficult and unreliable. Studies have shown that fast re-expanding blastocysts have superior pregnancy rates.

AIM

To determine whether the degree and speed of blastocoele re-expansion following cryopreservation and warming correlate with rates of live birth.

MATERIALS AND METHODS

A retrospective cohort study of 757 frozen embryo transfer cycles over a 4-year period at Royal Prince Alfred Hospital, Sydney. Clinical and embryology notes were retrieved. Details regarding patient demographics, stimulation cycle from which embryos were derived, frozen embryo transfer cycles, embryology and pregnancy outcomes were recorded.

RESULTS

Female (P = 0.01) and male age (P = 0.02) at the time of embryo creation were inversely associated with live birth. Fertilisation method (P = 0.03), embryo type at cryopreservation (P = 0.009), embryo grade at cryopreservation (P < 0.0001), percentage of cell survival post-thaw (P < 0.0001) and the degree of re-expansion (P = 0.003) were the IVF and embryology factors significantly associated with live birth. A predictive model (CryoPredict) was created in order to individualise the probability that the transfer of a given embryo would result in live birth.

CONCLUSIONS

The degree and speed of blastocoele re-expansion postcryopreservation and subsequent warming can be used in conjunction with other parameters to predict live birth.