Background Breech presentation at term contributes significantly to cesarean section (CS) rates worldwide. External cephalic version (ECV) is a safe procedure that reduces term breech presentation and associated CS. A principal barrier to ECV is failure to diagnose breech presentation. Failure to diagnose breech presentation also leads to emergency CS or unplanned vaginal breech birth. Recent evidence suggests that undiagnosed breech might be eliminated using a third trimester scan. Our aim was to evaluate the impact of introducing a routine 36-week scan on the incidence of breech presentation and of undiagnosed breech presentation. Methods and findings We carried out a population-based cohort study of pregnant women in a single unit covering Oxfordshire, United Kingdom. All women delivering between 37+0 and 42+6 weeks gestational age, with a singleton, nonanomalous fetus over a 4-year period (01 October 2014 to 30 September 2018) were included. The mean maternal age was 31 years, mean BMI 26, 44% were nulliparous, and 21% were of non-white ethnicity. Comparisons between the 2 years before and after introduction of routine 36-week scan were made for 2 primary outcomes of (1) the incidence of breech presentation and (2) undiagnosed breech presentation. Secondary outcomes related to ECV, mode of birth, and perinatal outcomes. Relative risks (RRs) with 95% confidence intervals (CIs) are reported. A total of 27,825 pregnancies were analysed (14,444 before and 13,381 after). A scan after 35+0 weeks was performed in 5,578 (38.6%) before, and 13,251 (99.0%) after (p < 0.001). The incidence of breech presentation at birth did not change significantly (2.6% and 2.7%) (RR 1.02; 95% CI 0.89, 1.18; p = 0.76). The rate of undiagnosed breech before labour reduced, from 22.3% to 4.7% (RR 0.21; 95% CI 0.12, 0.36; p < 0.001). Vaginal breech birth rates fell from 10.3% to 5.3% (RR 0.51; 95% CI 0.30, 0.87; p = 0.01); nonsignificant increases in elective CS rates and decreases in emergency CS rates for breech babies were seen. Neonatal outcomes were not significantly altered. Study limitations include insufficient numbers to detect serious adverse outcomes, that we cannot exclude secular changes over time which may have influenced our results, and that these findings are most applicable where a comprehensive ECV service exists. Conclusions In this study, a universal 36-week scan policy was associated with a reduction in the incidence but not elimination of undiagnosed term breech presentation. There was no reduction in the incidence of breech presentation at birth, despite a comprehensive ECV service.
Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality. Identifying which pregnancies are at risk of FGR facilitates enhanced surveillance and early delivery before fetal demise can ensue. However, existing risk stratification strategies yield an unacceptably low detection rate. A robust and reliable first trimester screening test for FGR would not only enable high-risk women to be appropriately monitored but would facilitate future trials for possible interventions to enhance fetal growth. Both the volume and vascularity of the first trimester placenta has been demonstrated to be linked to adverse pregnancy outcomes including FGR and pre-eclampsia. The investigation of novel ultrasound markers for FGR are discussed along with the development of methods for fully automatic placental volume estimation which has the potential for use as part of a multivariable population-based screening test. Aim To review novel automated techniques for ultrasound measurement of placental volume and utero-placental perfusion, and to illustrate how these might have utility in the development of a screening test for fetal growth restriction. Introduction Birth weight is dependent upon numerous factors including gestational age at the time of delivery [1]; maternal characteristics [1-3]; and placental volume, vasculature and function [4]. FGR is the term used to describe babies that do not achieve their inherent growth potential, and this term is often used synonymously with 'small-forgestational-age' (SGA) although the two are distinctly different. SGA is defined as a
Introduction Ultrasound assessment of fetuses subjected to hyperglycemia is recommended but, apart from increased size, little is known about its interpretation, and the identification of which large fetuses of diabetic pregnancy are at risk is unclear. Newer markers of adverse outcomes, abdominal circumference growth velocity and cerebro‐placental ratio, help to predict risk in non‐diabetic pregnancy. Our study aims to assess their role in pregnancies complicated by diabetes. Material and methods This is a retrospective analysis of a cohort of singleton, non‐anomalous fetuses of women with pre‐existing or gestational diabetes mellitus, and estimated fetal weight at the 10th centile or above. Gestational diabetes was diagnosed by selective screening of at risk groups. A universal ultrasound scan was offered at 20 and 36 weeks of gestation. Estimated fetal weight, abdominal circumference growth velocity, presence of polyhydramnios, and cerebro‐placental ratio were evaluated at the 36‐week scan. A composite adverse outcome was defined as the presence of one or more of perinatal death, arterial cord pH less than 7.1, admission to Neonatal Unit, 5‐minute Apgar less than 7, severe hypoglycemia, or cesarean section for fetal compromise. A chi‐squared test was used to test the association of estimated fetal weight at the 90th centile or above, polyhydramnios, abdominal circumference growth velocity at the 90th centile or above, and cerebro‐placental ratio at the 5th centile or below with the composite outcome. Logistic regression was used to assess which ultrasound markers were independent risk factors. Odds ratios of composite adverse outcome with combinations of independent ultrasound markers were calculated. Results A total of 1044 pregnancies were included, comprising 87 women with pre‐existing diabetes mellitus and 957 with gestational diabetes. Estimated fetal weight at the 90th centile or above, abdominal circumference growth velocity at the 90th centile or above, cerebro‐placental ratio at the 5th centile or below, but not polyhydramnios, were significantly associated with adverse outcomes: odds ratios (95% confidence intervals) 1.85 (1.21–2.84), 1.54 (1.02–2.31), 1.92 (1.21–3.30), and 1.53 (0.79–2.99), respectively. Only estimated fetal weight at the 90th centile or above and cerebro‐placental ratio at the 5th centile or below were independent risk factors. The greatest risk (odds ratio 6.85, 95% confidence interval 2.06–22.78) was found where both the estimated fetal weight is at the 90th centile or above and the cerebro‐placental ratio is at the 5th centile or below. Conclusions In diabetic pregnancies, a low cerebro‐placental ratio, particularly in a macrosomic fetus, confers additional risk.
What are the novel findings of this work?The use of different combinations of commonly used estimated-fetal-weight and birth-weight reference charts can result in a 4-fold difference in small-for-gestationalage detection rates in the same dataset. Detection rates are influenced further by the choice of reference scan. Similar findings are seen for the detection of large-for-gestationalage cases. What are the clinical implications of this work?Unless there is consistency in the use of estimated-fetalweight and birth-weight reference charts, comparison of detection rates between care providers may be misleading. Methodological transparency in reporting is required, and where the intention is to allow comparison between care providers, a unified approach should be adopted.
Objective To investigate perinatal mortality, morbidity and obstetric intervention following the introduction of a universal late third‐trimester ultrasound scan for growth restriction. Design Prospective cohort study. Setting Oxfordshire (OUH), UK. Population Women with a non‐anomalous singleton pregnancy undergoing pregnancy care and term delivery at OUH with an estimated due date (EDD) of birth between 1 January 2014 and 30 September 2019. Methods Universal ultrasound for fetal growth restriction between 35+0 and 36+6 weeks was introduced in 2016. The outcomes of the next 18 631 eligible term pregnancies were compared, adjusting for covariates and time, with the previous 18 636 who had clinically indicated ultrasounds only. ‘Screen‐positives’ for growth restriction were managed according to a pre‐determined protocol which included non‐intervention for some small‐for‐gestational‐age babies. Main Outcome Measures Extended perinatal mortality, a composite of mortality or encephalopathy Grade II–III, and expedited birth. Other outcomes included composite adverse outcomes used elsewhere, detection of low birthweight and birth from 37+0 to 38+6 weeks. Results Extended perinatal deaths decreased 27% and severe morbidity decreased 33% but neither change was statistically significant (adjusted odd ratio [aOR] 0.53, 95% confidence interval [C1] 00.18–1.56 and aOR 0.71, 95% CI 0.31–1.63). Expedited births changed from 35.2% to 37.7% (aOR 0.99, 95% CI 0.92–1.06). Birthweight (<10th centile) detection using fetal biometry alone was 31.4% and rose to 40.5% if all abnormal scan parameters were used. Conclusion Improvements in mortality and severe morbidity subsequent to introducing a universal ultrasound for growth restriction are encouraging but remain unclear. Little change in intervention is possible. The antenatal detection of low birthweight remains poor but improves where markers of growth restriction are used.
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