Browsing by Author "Southwest Thames Obstetric Research Collaborative (STORK)"

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Does antenatal ultrasound labeling predict birth order in twin pregnancies?
(Wiley, 2013) D'Antonio, F.; Dias, T.; Thilaganathan, B.; Southwest Thames Obstetric Research Collaborative (STORK)
OBJECTIVE: It is often assumed by obstetricians, neonatologists and parents that the prenatal nomenclature used to identify twins on ultrasound is consistent with twin labeling after their birth. The aim of this study was to use a large regional database of twin ultrasound scans to validate the effectiveness of a scan before delivery in predicting twin birth-order. METHODS: A large regional database of twin ultrasound scans with data from nine hospitals over a 10-year period was used to identify all ultrasound examinations carried out just before birth. The discordance in twin order between the last scan and birth was evaluated by observing discrepancies in fetal sex and weight. RESULTS: In total, 2103 twin pregnancies with ultrasound estimated fetal weights (EFWs) and birth weights were assessed. Of these, fetal sex was recorded in 149 different-sex pregnancies. Discrepancy between antenatal labeling and the anticipated birth order was noted in 37.6% (56/149) of cases when judged by sex discordance and in 36% (757/2103) of cases when judged by weight discordance. Multiple logistic regression analyses demonstrated that weight discordance, but not chorionicity, scan-to-delivery interval, gestation at scan or gestation at delivery, significantly influenced the change in birth order (P < 0.001). CONCLUSION: Antenatal ultrasound labeling does not predict twin birth-order in a significant proportion of twin deliveries. This finding should be borne in mind not only by parents, but also by physicians when delivering twins discordant for anomalies that are not evident on external examination
Early fetal loss in monochorionic and dichorionic twin pregnancies: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort
(Wiley, 2013) D'Antonio, F.; Khalil, A.; Dias, T.; Thilaganathan, B.; Southwest Thames Obstetric Research Collaborative (STORK)
OBJECTIVES: Monochorionic (MC) twins are at increased risk of early fetal loss secondary to vascular complications such as twin-twin transfusion syndrome (TTTS). This study compared the early perinatal loss rates between MC and dichorionic (DC) twins in an era of invasive treatment for TTTS. METHODS: This was a retrospective study of all twin pregnancies of known chorionicity from a large regional cohort of nine hospitals over a 10-year period. Ultrasound data were matched to hospital delivery records and to a mandatory national register of pregnancy losses. Prospective risk of pregnancy loss from 14 to 24 weeks' gestation was calculated and the survival trend of MC and DC twins was analyzed using Kaplan-Meier survival analysis. RESULTS: The analysis included 3117 twin pregnancies (605 MC and 2512 DC). The total risk of early pregnancy loss (miscarriage and neonatal death) before 24 weeks was significantly higher in MC twins (60.3 per 1000 fetuses) than in DC twins (6.6 per 1000 fetuses), with a relative risk of 9.18 (95% CI, 6.0-13.9). Survival analysis showed a significant difference in overall and early mortality between MC and DC twins (log-rank test, P < 0.0001), while no difference was noted after 24 weeks' gestation (log-rank test, P = 0.08). CONCLUSIONS: Early pregnancy loss is significantly more common in MC than in DC twins, but no difference in the prospective risk of mortality between MC and DC twins is evident after 24 weeks' gestation. The observed early mortality rate has almost halved in comparison with previous studies in the published literature. Early detection and prompt treatment of complications in MC twins are likely to have contributed to this improvement in outcome. Copyright © 2012 ISUOG. Published by John Wiley & Sons Ltd.
The influence of chorionicity and gestational age at single fetal loss on the risk of preterm birth in twin pregnancies: analysis of the STORK multiple pregnancy cohort
(Wiley, 2017) D'Antonio, F.; Thilaganathan, B.; Dias, T.; Khalil, A.; Southwest Thames Obstetric Research Collaborative (STORK)
BACKGROUND: Single intrauterine death (sIUD) in twin pregnancies is associated with a significant risk of co-twin demise and pretermbirth (PTB), especially in monochorionic (MC) twins. However, it is yet to be established whether the gestational age at loss may influence the pregnancy outcome. The aim of this study was to explore the risk of PTB according to the gestational age at the diagnosis of sIUD. METHODS: A cohort study of all twin pregnancies from a large regional network of 9 hospitals over a ten-year period. Ultrasound data was matched to hospital delivery records and a mandatory national register for perinatal losses (CMACE). Cases with double fetal loss at the time of the scan were not included in the analysis. The cumulative rates of PTB before 34, 32 and 28 weeks of gestation was assessed in pregnancies which did vs those which did not experience sIUD. The risk of PTB was stratified according to the gestationalage at the diagnosis of sIUD. RESULTS: The analysis included 3013 twin gestations (2469 DC and 544 MC) . Median gestational age at birth was lower in the pregnancies complicated by sIUD compared to those which were not (32.0 weeks, IQR 29.0-34.3 vs 36.7 weeks, IQR 35.0-37.6; p < 0.001) and this difference persisted when stratifying the analysis according to chorionicity (p < 0.0001 for both MC and DC pregnancies). The risk of PTB before 34 weeks (RR: 4.3, 95% CI 3.5-5.2), before 32 weeks (RR: 6.1, 95% CI 4.6-8.1) and before 28 weeks (RR: 12.40, 95% CI 6.9-22.2) was higher in pregnancies complicated by a sIUD compared to those which did not experience any fetal loss. This association was observed both in MC and DC twin gestations. When compared to DC pregnancies, MC twins affected by sIUD were not at significantly increased risk of PTB either before 34, 32 or 28 weeks of gestation. The risk of PTB before 34 weeks of gestation was higher when the sIUD occurred at a later gestational age (Chi-square test for trend, p < 0.001). CONCLUSION: Twin pregnancies complicated by sIUD, regardless of the chorionicity, have a significantly higher risk of PTB before 34, 32 and 28 weeks of gestation. The risk of PTB before 34 weeks of gestation was higher when the sIUD occurred in the second half of the pregnancy. Large prospective multicenter studies with shared protocols for prenatal management are needed to ascertain the actual risk of spontaneous PTB in twin pregnancies affected by sIUD.
Ultrasound estimation of birthweight in twin pregnancy: comparison of biometry algorithms in the STORK multiple pregnancy cohort.
(Wiley, 2014) Khalil, A.; D'Antonio, F.; Dias, T.; Cooper, D.; Thilaganathan, B.; Southwest Thames Obstetric Research Collaborative (STORK)
OBJECTIVES: The aims of this study were first, to ascertain the accuracy of formulae for ultrasonographic birth-weight estimation in twin compared with singleton pregnancies and second, to assess the accuracy of sonographic examination in the prediction of birth-weight discordance in twinpregnancies. METHODS: This was a retrospective cohort study including both singleton and twin pregnancies. Routine biometry was recorded and estimated fetalweight (EFW) calculated using 33 different formulae. Only pregnancies that delivered within 48 h of the ultrasound scan were included (4280 singleton and 586 twin fetuses). Differences between the EFW and actual birth weight (ABW) were assessed by percentage error, accuracy in predictions within ± 10 % and ± 15% of error and use of the Bland-Altman method. The accuracy of prediction of the different cut-offs of birth-weight discordance intwin pregnancies was also assessed using the area under the receiver-operating characteristics curve (AUC). RESULTS: The overall mean absolute percentage error was ≤ 10 % for 25 formulae in singleton pregnancies compared with three formulae in twinpregnancies. The overall predictions within ± 10% and ± 15% of the ABW were 62.2% and 81.5% in singleton and 49.7% and 68.5% in twinpregnancies, respectively. When the formulae were categorized according to the biometric parameters included, those based on a combination of head, abdomen and femur measurements showed the lowest mean absolute percentage error, in both singleton and twin pregnancies. The predictive accuracy for 25% birth-weight discordance using the Hadlock 2 formula, as assessed by the AUC, was 0.87. CONCLUSIONS: Ultrasound estimation of birth weight is less accurate in twin than in singleton pregnancies. Formulae that include a combination of head, abdomen and femur measurements perform best in both singleton and twin pregnancies.
Weight discordance and perinatal mortality in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort
(Wiley, 2013) D'Antonio, F.; Khalil, A.; Dias, T.; Thilaganathan, B.; Southwest Thames Obstetric Research Collaborative (STORK)
OBJECTIVES: The degree of actual intertwin birth weight (BW) or ultrasound estimated fetal weight (EFW) discordance that justifies elective delivery is yet to be established. The main aim of this study was to ascertain the performance of BW and ultrasound EFW discordance in the prediction ofperinatal loss in twin pregnancies. METHODS: This was a retrospective study of all twin pregnancy births from a large regional cohort of nine hospitals over a 10-year period. Intertwin BW and ultrasound EFW discordance were analyzed in relation to the occurrence of stillbirth or neonatal death of one or both twins from 26 weeks' gestation as obtained from a mandatory national register. Receiver-operating characteristics (ROC), survival and logistic regression analyses were performed to evaluate the contribution of weight discordance in determining perinatal loss. RESULTS: A total of 2161 twin pregnancies were included in the analysis. The area under the ROC curve for the prediction of perinatal loss was similar for BW and ultrasound EFW discordance (P = 0.62). Kaplan-Meier analysis showed that twins with BW or EFW of ≥ 25% discordance had a significantly lower survival trend than did those with lesser degrees of discordance (P < 0.001). The hazard ratios for the risk of total perinatal loss intwins with a BW or EFW discordance of ≥ 25% were 7.29 (95% CI, 4.37-12.00) and 7.28 (95% CI, 4.46-11.92), respectively. Logistic regression analysis demonstrated that BW discordance and gestational age, but not chorionicity or individual fetal size percentile, were independently associated with perinatal mortality. CONCLUSIONS: An EFW discordance of ≥ 25% represents the optimal cut-off for the prediction of stillbirth and neonatal mortality irrespective of chorionicity or individual fetal size. A policy of increased fetal surveillance commencing from 26 weeks' gestation might be reasonable for pregnancies beyond this cut-off, but this would require confirmation in large-scale prospective trials. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd