Adverse perinatal outcomes in borderline amniotic fluid index

Perinatal Outcomes of Pregnancies with Borderline Oligohydramnios at Term

INTRODUCTION

Limited evidence exists on borderline oligohydramnios. Our objective was to determine perinatal outcomes in uncomplicated term pregnancies with borderline oligohydramnios.

METHODS

This retrospective analysis compared adverse perinatal outcomes among pregnancies during 2018-2022, between those with borderline oligohydramnios defined as amniotic fluid index (AFI) of 5.1-8.0 cm, those with oligohydramnios (AFI ≤5 cm), and those with normal AFI (8.1-25 cm). The latter matched one-to-one to the borderline oligohydramnios group and served as the control group. The outcomes compared included birthweight, cesarean delivery due to fetal distress, the presence of meconium-stained amniotic fluid, Apgar scores, neonatal intensive care unit admission, and the occurrence of small-for-gestational-age (SGA) neonates.

RESULTS

During the study period, 140 women had borderline oligohydramnios and 345 had oligohydramnios; the control group included 140 women. Borderline oligohydramnios was associated with increased rates of delivering SGA neonates (adjusted odds ratio [aOR] = 3.6, 95% confidence interval [CI] 1.1-11.6, p = 0.034) and cesarean delivery due to fetal distress (aOR = 3.0, 95% CI 1.1-8.3, p = 0.032). Rates of composite neonatal outcome (including at least one of the following: cesarean delivery due to fetal distress, meconium-stained amniotic fluid, 5-min Apgar score <7, umbilical artery pH <7.15, or neonatal intensive care unit admission) were higher in both the borderline oligohydramnios (20.7%) and oligohydramnios (18.6%) groups compared to the control group (9.3%) (p = 0.019).

CONCLUSIONS

Pregnancies with borderline oligohydramnios were associated with increased risks of delivering SGA neonates and requiring cesarean delivery due to fetal distress. These findings support considering closer antepartum surveillance for these pregnancies, especially for identifying abnormal fetal growth.

Comparison of the effectiveness and pregnancy outcomes of labor induction with dinoprostone or single-balloon catheter in term nulliparous women with borderline oligohydramnios

BACKGROUNDS

At present, there is no consensus on the induction methods in term pregnancy with borderline oligohydramnios. This study aimed to compare the effectiveness and pregnancy outcomes of labor induction with dinoprostone or single-balloon catheter (SBC) in term nulliparous women with borderline oligohydramnios.

METHODS

We conducted a retrospective cohort study from January 2016 to November 2018. During the study period, a total of 244 cases were enrolled. Of these, 103 cases were selected for induction using dinoprostone and 141 cases were selected for induction with SBC. The pregnancy outcomes between the two groups were compared. Primary outcomes were successful vaginal delivery rates. Secondary outcomes were maternal and neonatal adverse events. Multivariate logistic regression was used to assess the risk factors for vaginal delivery failure in the two groups.

RESULTS

The successful vaginal delivery rates were similar between the dinoprostone group and the SBC group (64.1% [66/103] vs. 59.6%, [84/141] P = 0.475), even after adjustment for potential confounding factors (adjusted odds ratio [aOR]: 1.07, 95% confidence interval [CI]: 0.57-2.00, P = 0.835). The incidence of intra-amniotic infection was lower in the dinoprostone group than in the SBC group (1.9% [2/103] vs. 7.8%, [11/141] P < 0.001), but the presence of non-reassuring fetal heart rate was higher in the dinoprostone group than in the SBC group (12.6% [13/103] vs. 0.7%, [1/141] P < 0.001). Multivariate logistic regression showed that nuchal cord was a risk factor for vaginal delivery failure after induction with dinoprostone (aOR: 6.71, 95% CI: 1.96-22.95). There were three factors related to vaginal delivery failure after induction with SBC, namely gestational age (aOR: 1.51, 95% CI: 1.07-2.14), body mass index (BMI) >30 kg/m2 (aOR: 2.98, 95% CI: 1.10-8.02), and fetal weight >3500 g (aOR: 2.49, 95% CI: 1.12-5.50).

CONCLUSIONS

Term nulliparous women with borderline oligohydramnios have similar successful vaginal delivery rates after induction with dinoprostone or SBC, with their advantages and disadvantages. In women with nuchal cord, the risk of vaginal delivery failure is increased if dinoprostone is used in the induction of labor. BMI >30 kg/m2, large gestational age, and estimated fetal weight >3500 g are risk factors for vaginal delivery failure after induction with SBC.

Amniotic fluid index curves in the obese gravida

OBJECTIVE

To determine whether amniotic fluid volume as measured by amniotic fluid index (AFI) is influenced by maternal pre-gestational obesity as measured by body mass index (BMI).

METHODS

This was a retrospective cohort study of pregnant women between 20 and 43 weeks gestation receiving ultrasounds with AFI measurements at Augusta University Medical Center between 2003 and 2017. A subset of 500 charts that met inclusion and exclusion criteria were reviewed to obtain maternal clinical data. The study cohort was subdivided by maternal BMI at initial obstetric visit into three groups: normal weight (18.5 kg/m2-24.9 kg/m2), overweight (25.0 kg/m2-29.9 kg/m2), and obese (≥ 30 kg/m2). Chi-square analysis was used to compare BMI groups in terms of categorical clinical characteristics and outcome variables, and analysis of variance (ANOVA) was used for continuous variables. Mixed effects regression models (MRMs) were used to evaluate AFI throughout gestation separately in each group, and MRM-based analysis of covariance was used to compare AFI throughout gestation among groups. AFI curves were constructed for the 5th, 50th, and 95th percentiles for all study subjects combined and separately for normal weight, overweight, and obese subjects.

RESULTS

Fitted curves relating AFI percentiles to estimated gestational age (EGA) showed statistically significant differences among BMI groups. There was also a significant difference in AFI over gestation across the obesity groups.

CONCLUSION

Fitted curves for AFI throughout pregnancy showed statistically significant differences among BMI groups.

Universal late pregnancy ultrasound screening to predict adverse outcomes in nulliparous women: a systematic review and cost-effectiveness analysis

BACKGROUND

Currently, pregnant women are screened using ultrasound to perform gestational aging, typically at around 12 weeks' gestation, and around the middle of pregnancy. Ultrasound scans thereafter are performed for clinical indications only.

OBJECTIVES

We sought to assess the case for offering universal late pregnancy ultrasound to all nulliparous women in the UK. The main questions addressed were the diagnostic effectiveness of universal late pregnancy ultrasound to predict adverse outcomes and the cost-effectiveness of either implementing universal ultrasound or conducting further research in this area.

DESIGN

We performed diagnostic test accuracy reviews of five ultrasonic measurements in late pregnancy. We conducted cost-effectiveness and value-of-information analyses of screening for fetal presentation, screening for small for gestational age fetuses and screening for large for gestational age fetuses. Finally, we conducted a survey and a focus group to determine the willingness of women to participate in a future randomised controlled trial.

DATA SOURCES

We searched MEDLINE, EMBASE and the Cochrane Library from inception to June 2019.

REVIEW METHODS

The protocol for the review was designed a priori and registered. Eligible studies were identified using keywords, with no restrictions for language or location. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Health economic modelling employed a decision tree analysed via Monte Carlo simulation. Health outcomes were from the fetal perspective and presented as quality-adjusted life-years. Costs were from the perspective of the public sector, defined as NHS England, and the costs of special educational needs. All costs and quality-adjusted life-years were discounted by 3.5% per annum and the reference case time horizon was 20 years.

RESULTS

Umbilical artery Doppler flow velocimetry, cerebroplacental ratio, severe oligohydramnios and borderline oligohydramnios were all either non-predictive or weakly predictive of the risk of neonatal morbidity (summary positive likelihood ratios between 1 and 2) and were all weakly predictive of the risk of delivering a small for gestational age infant (summary positive likelihood ratios between 2 and 4). Suspicion of fetal macrosomia is strongly predictive of the risk of delivering a large infant, but it is only weakly, albeit statistically significantly, predictive of the risk of shoulder dystocia. Very few studies blinded the result of the ultrasound scan and most studies were rated as being at a high risk of bias as a result of treatment paradox, ascertainment bias or iatrogenic harm. Health economic analysis indicated that universal ultrasound for fetal presentation only may be both clinically and economically justified on the basis of existing evidence. Universal ultrasound including fetal biometry was of borderline cost-effectiveness and was sensitive to assumptions. Value-of-information analysis indicated that the parameter that had the largest impact on decision uncertainty was the net difference in cost between an induced delivery and expectant management.

LIMITATIONS

The primary literature on the diagnostic effectiveness of ultrasound in late pregnancy is weak. Value-of-information analysis may have underestimated the uncertainty in the literature as it was focused on the internal validity of parameters, which is quantified, whereas the greatest uncertainty may be in the external validity to the research question, which is unquantified.

CONCLUSIONS

Universal screening for presentation at term may be justified on the basis of current knowledge. The current literature does not support universal ultrasonic screening for fetal growth disorders.

FUTURE WORK

We describe proof-of-principle randomised controlled trials that could better inform the case for screening using ultrasound in late pregnancy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017064093.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 15. See the NIHR Journals Library website for further project information.

Perinatal outcomes following labor induction with dinoprostone in pregnancies with borderline amniotic fluid index at term: A clinical observation study

AIM

To compare perinatal outcomes of dinoprostone for induced labor in pregnancies with a borderline versus normal amniotic fluid index (AFI) at term, and to investigate the related factors affecting outcomes of cesarean section.

METHODS

The retrospective study was carried out in Hubei Maternal and Child Health Hospital with singleton pregnancies of 37-42 weeks' gestation from January to August 2016. A total of 992 subjects were divided into two groups: borderline AFI group (n =125) with 5 < AFI ≤ 8 and normal AFI group (n = 867) with 8 < AFI ≤ 24.

RESULTS

Time to delivery (P =0.004) and use of oxytocin augmentation (P = 0.011) were significantly lower in pregnancies with borderline AFI. There were no significant differences between the two groups in terms of delivery mode, time to onset of labor, fetal distress, Apgar scores, meconium-stained amniotic fluid, birth weight, or incidences of admission to neonatal intensive care unit (NICU). Gestational hypertension and birth weight were the major factors affecting outcomes of cesarean section in the borderline group (odds ratio [OR] = 13.61, 95% confidence interval [CI] 1.96-94.49, P =0.008 and OR = 1.003, 95% CI 1.001-1.005, P =0.001, respectively). Maternal age (OR = 1.12, 95% CI 1.06-1.19, P < 0.001), parity (OR = 7.57, 95% CI 3.05-18.76, P < 0.001), biparietal diameter (OR = 0.55, 95% CI 0.33-0.91, P = 0.021), and meconium-stained amniotic fluid (OR = 1.56, 95% CI 1.12-2.17, P = 0.009) were related factors in the normal group.

CONCLUSION

The perinatal outcomes of dinoprostone for induced labor are comparable between the two groups. Gestational hypertension and birth weight are factors related to outcomes of cesarean section in the borderline group.