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Objective: The ability to predict the need for emergency Cesarean delivery holds the potential to facilitate birth choices. The objective of the RECIPE study (Reducing Emergency Cesarean delivery and Improving the Primiparous Experience) was to externally validate a Cesarean delivery risk prediction model. This model, developed by the Genesis study, identified five key predictive factors for emergency Cesarean delivery: maternal age, maternal height, BMI, fetal head circumference (HC) and fetal abdominal circumference (AC)., Study Design: This prospective, observational study was conducted in two tertiary referral perinatal centers. Inclusion criteria were as follows: primiparous women with a singleton, cephalic presentation fetus in the absence of fetal growth restriction (FGR), oligohydramnios, pre-eclampsia, pre-existing diabetes mellitus or an indication for planned Cesarean delivery. Between 38 + 0 and 40 + 6 weeks' gestational age, participants attended for prenatal assessment that enabled the determination of an individualized risk calculation for emergency Cesarean delivery during labour based on maternal height, BMI, fetal HC and AC, with crucially both participants and care providers being blinded to the resultant risk prediction score. Labor, delivery and postnatal outcomes were ascertained. Calibration and receiver operator curves were generated to determine the predictive capacity for emergency Cesarean delivery of the Genesis risk prediction model in this cohort., Results: 559 primiparous participants were enrolled from May 2017 to April 2019, of whom 142 (25 %) had an emergency Cesarean delivery during labour. Participants with a low predicted risk score (<10 %) had a mean predicted rate of 8% (+/- standard deviation of 2%) and a similarly low actual observed rate of Cesarean delivery (8%). Participants with a high predicted risk (>50 %) had a mean predicted Cesarean delivery rate of 64 % (+/- standard deviation of 9%) and also had a high actual observed Cesarean delivery rate (62 %). The calibration curve and receiver operating characteristic curve demonstrated that this validation study had comparable discriminatory power for emergency Cesarean delivery to that described in the original Genesis study. The Area Under the Curve (AUC) in Genesis was 0.69, whereas the AUC in RECIPE was 0.72, which reflects good predictive capacity of the risk prediction model., Conclusion: The accuracy of the Genesis Cesarean delivery prediction tool is supported by this validation study., Competing Interests: Declaration of Competing Interest The authors report no declarations of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: Our study aim was to evaluate standard ultrasound-derived fetal biometric parameters in the prediction of clinically significant intertwin birthweight discordance defined as ≥18%., Material and Methods: This was a secondary analysis of a prospective cohort study of 1028 unselected twin pairs recruited over a two-year period. Dichorionic twins underwent two-weekly ultrasonographic surveillance from 24 weeks' gestation, with surveillance of monochorionic twins two-weekly from 16 weeks. Ultrasonographic biometric data from 24 to 36 weeks were evaluated for the prediction of an intertwin birthweight discordance threshold ≥18%. Umbilical artery Doppler waveform data was also analyzed to evaluate whether it was predictive of birthweight discordance., Results: Of the 956 twin pairs analyzed for discordance, 208 pairs were found to have a clinically significant birthweight discordance ≥18%. All biometric parameters were predictive of significant inter-twin birthweight discordance at low cut-offs, with low discriminatory powers when ROC curves were analyzed. Discordance in estimated fetal weight was predictive of a significant birthweight discordance at all gestational categories with cut-offs between 8 and 11%. A low-discriminatory power and poor sensitivity and specificity were also observed. An abnormal umbilical artery Doppler was predictive of birthweight discordance ≥18% between 28 and 32 weeks' gestation, although with poor sensitivity and specificity., Conclusions: Calculation of estimated fetal weight and birthweight discordance between twins allows minimal margin for error. These margins make it difficult to accurately predict those who are at or above the discordance threshold of 18%. These findings highlight that small intertwin discrepancies in weight and biometry should not be overlooked and merit further investigation., (© 2017 Nordic Federation of Societies of Obstetrics and Gynecology.)

Unlabelled: Our aims were to study the effect of birthweight growth discordance (≥20%) on neuro-developmental outcome of monochorionic and dichorionic twins and to compare the relative effects of foetal growth discordance and prematurity on cognitive outcome. We performed a cross-sectional multicentre prospective follow-up study from a cohort of 948 twin pregnancies. One hundred nineteen birthweight-discordant twin pairs were examined (24 monochorionic pairs) and were matched for gestational age at delivery with 111 concordant control pairs. Participants were assessed with the Bayley Scales between 24 and 42 months of age. Analysis was by paired t test for intra-twin pair differences and by multiple linear regression. Compared to the larger twin of a discordant pair, the smaller twin performed significantly worse in cognition (mean composite cognitive score difference = -1.7, 95% confidence interval (CI) = 0.3-3.1, p = 0.01) and also in language and motor skills. Prematurity prior to 33 weeks' gestation, however, had a far greater impact on cognitive outcomes (mean cognitive composite score difference = -5.8, 95% CI = 1.2-10.5, p = 0.008)., Conclusion: Birthweight growth discordance of ≥20% confers an independent adverse effect on long-term neuro-development of the smaller twin. However, prior to 33 weeks' gestation, gestational age at birth adversely affects cognitive development to a greater extent than foetal growth discordance.

Objective: We sought to evaluate the association between placental histological abnormalities and birthweight discordance and growth restriction in twin pregnancies., Study Design: We performed a multicenter, prospective study of twin pregnancies. Placentas were examined for evidence of infarction, retroplacental hemorrhage, chorangioma, subchorial fibrin, or abnormal villus maturation. Association of placental lesions with chorionicity, birthweight discordance, and growth restriction were assessed., Results: In all, 668 twin pairs were studied, 21.1% monochorionic and 78.9% dichorionic. Histological abnormalities were more frequent in placentas of smaller twins of birthweight discordant pairs (P = .02) and in placentas of small for gestational age infants (P = .0001) when compared to controls. The association of placental abnormalities with both birthweight discordance and small for gestational age was significant for dichorionic twins (P = .01 and .0001, respectively). No such association was seen in monochorionic twins., Conclusion: In a large, prospective, multicenter study, we observed a strong relationship between abnormalities of placental histology and birthweight discordance and growth restriction in dichorionic, but not monochorionic, twin pregnancies., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Twin growth is frequently mismatched. This review serves to explore the pathophysiologic mechanisms that underlie growth aberrations in twin gestations, the prenatal recognition of abnormal twin growth, and the critical importance of stratifying management of abnormal twin growth by chorionicity. Although poor in utero growth of both twins may reflect maternal factors resulting in global uteroplacental dysfunction, discordant twin growth may be attributed to differences in genetic potential between co-twins, placental dysfunction confined to one placenta only, or one placental territory within a shared placenta. In addition, twin-twin transfusion syndrome represents a distinct entity of which discordant growth is a common feature. Discordant growth is recognized as an independent risk factor for adverse perinatal outcome. Intertwin birth weight disparity of 18% or more should be considered to represent a discordance threshold, which serves as an independent risk factor for adverse perinatal outcome. At this cutoff, perinatal morbidity is found to increase both for the larger and the smaller twin within a discordant pair. There remains uncertainty surrounding the sonographic parameters that are most predictive of discordance. Although heightening of fetal surveillance in the face of discordant twin growth follows the principles applied to singleton gestations complicated by fetal growth restriction, the timing of intervention is largely influenced by chorionicity., (Copyright © 2012 Elsevier Inc. All rights reserved.)