Morbidity and mortality of discordant twins up to 34 weeks of gestational age

Long-term adverse neurodevelopmental outcomes of discordant twins delivered at term: A nationwide population-based study

OBJECTIVE

To evaluate long-term adverse neurodevelopmental outcomes of discordant twins delivered at term.

DESIGN

Retrospective cohort study.

SETTING

Nationwide (Republic of Korea).

POPULATION

All twin children delivered at term between 2007 and 2010.

METHODS

The study population was divided into two groups according to inter-twin birthweight discordancy: the 'concordant twin group', twin pairs with inter-twin birthweight discordancy less than 20%; and the 'discordant twin group', twin pairs with inter-twin birthweight discordancy of 20% or more. The risk of long-term adverse neurodevelopmental outcomes was compared between the concordant twin group and the discordant twin group. Long-term adverse neurodevelopmental outcomes between smaller and larger twin children within twin pairs were further analysed. The composite adverse neurodevelopmental outcome was defined as the presence of at least one of the following: motor developmental delay, cognitive developmental delay, autism spectrum disorders/attention deficit hyperactivity disorders, tics/stereotypical behaviour or epileptic/febrile seizure.

MAIN OUTCOME MEASURES

Long-term adverse neurodevelopmental outcome.

RESULTS

Of 22 468 twin children (11 234 pairs) included, 3412 (15.19%) twin children were discordant. The risk of composite adverse neurodevelopmental outcome was higher in the discordant twin group than in the concordant twin group (adjusted hazard ratio [HR] 1.13, 95% CI 1.03-1.24). The long-term adverse neurodevelopmental outcomes were not significantly different between smaller and larger twin children in discordant twin pairs (adjusted HR 1.01, 95% CI 0.81-1.28).

CONCLUSION

In twin pairs delivered at term, an inter-twin birthweight discordancy of 20% or greater was associated with long-term adverse neurodevelopmental outcomes; and long-term adverse neurodevelopmental outcomes were not significantly different in smaller or larger twin children in discordant twin pairs.

Neonatal outcomes between discordant monochorionic and dichorionic twins

OBJECTIVES

This study aimed to compare obstetrical complications and neonatal outcomes between monochorionic and dichorionic discordant twin pregnancies.

STUDY DESIGN

We enrolled 296 patients with twin pregnancy who delivered at Busan Paik Hospital between January 2014 and December 2017. The prevalence of obstetrical complications, neonatal mortality between monochorionic and dichorionic twins was compared. We also investigated whether there is a difference in neonatal outcome and neonatal morbidity between monochorionic discordant twins without monochorionic-specific complications and dichorionic discordant twins.

RESULTS

The risk of fetal death in utero (13.2 versus 5.2%, p = .025) and inter twin birth weight discordance (35.1 versus 20.8%, p = .031) is increased in monochorionic twins than in dichorionic twins. However, no difference was noted in obstetrical complication and neonatal mortality and morbidity between two groups. Among twin pregnancies with intertwin birth weight discordance, after excluding fetal death in utero and monochorionic specific complication, there was no difference in obstetrical complication and neonatal mortality and morbidity according to chorionicity. There was no difference in neonatal morbidity between monochorionic twins and dichorionic twins when comparing larger neonates and smaller neonates of each group.

CONCLUSIONS

Risk of birth weight discordance is higher in monochorionic twin but no significant difference was observed in maternal outcomes, neonatal mortality and morbidity between noncomplicated monochorionic and dichorionic discordant twins.

Birth-weight discordance and neonatal morbidity in twin pregnancy: analysis of STORK multiple pregnancy cohort

OBJECTIVES

To investigate the relationship between weight discordance and neonatal morbidity in twin pregnancy progressing to at least 34 weeks of gestation. The secondary aim was to determine the predictive accuracy of different weight discordance cut-offs in predicting neonatal morbidity in twin pregnancy.

METHODS

This was a retrospective multicenter cohort study of all twin pregnancies booked for antenatal care at four hospitals in the Southwest Thames region of London Obstetric Research Collaborative (STORK) over a period of 10 years. Ultrasound data were obtained by a search of each hospital's obstetric ultrasound computer database, while outcome details were obtained from the computerized maternity and neonatal records. The primary outcome was incidence of composite neonatal morbidity in twin pregnancy with birth-weight discordance. Logistic regression was used to identify and adjust for potential confounders, while a receiver-operating characteristics (ROC) curve was used to determine predictive accuracy.

RESULTS

Nine hundred and thirty-nine twin pregnancies (760 dichorionic, 179 monochorionic) were included. Gestational age at birth and birth-weight decile were significantly lower in pregnancies complicated by neonatal morbidity compared with those which were not (P < 0.001 for both). On multivariable logistic regression analysis, gestational age at birth (P < 0.001), birth-weight decile (P = 0.029) and birth-weight discordance (P = 0.019), but not chorionicity (P = 0.477) or presence of at least one small-for-gestational-age (SGA) twin (P = 0.245), were associated independently with the risk of neonatal morbidity. There was a progressive increase in the risk of neonatal morbidity with increasing birth-weight discordance. Despite this association, birth-weight discordance showed an overall poor predictive accuracy for neonatal morbidity, with an area under the ROC curve of 0.58 (95% CI, 0.53-0.63) with an optimal cut-off of 17.6%, showing sensitivity and specificity of 35.2% (95% CI, 27.8-43.2%) and 83.2% (95% CI, 80.4-85.8%), respectively.

CONCLUSION

Intertwin birth-weight discordance is associated independently with the risk of neonatal morbidity in twins born after 34 weeks' gestation, irrespective of chorionicity or diagnosis of SGA in either twin. However, its predictive accuracy for neonatal morbidity is poor. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Weight discordance and perinatal mortality in twin pregnancy: systematic review and meta-analysis

OBJECTIVES

The primary aim of this systematic review was to explore the strength of association between birth-weight (BW) discordance and perinatal mortality in twin pregnancy. The secondary aim was to ascertain the contribution of gestational age and growth restriction in predicting mortality in growth-discordant twins.

METHODS

MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched. Only studies reporting on the risk of mortality in twin pregnancies affected compared with those not affected by BW discordance were included. The primary outcomes explored were incidence of intrauterine death (IUD), neonatal death (NND) and perinatal death. Outcome was assessed separately for monochorionic (MC) and dichorionic (DC) twin pregnancies. Analyses were stratified according to BW discordance cut-off (≥ 15%, ≥ 20%, ≥ 25% and ≥ 30%) and selected gestational characteristics, including incidence of IUD or NND before and after 34 weeks' gestation, presence of at least one small-for-gestational age (SGA) fetus in the twin pair and both twins being appropriate-for-gestational age. Risk of mortality in the larger vs smaller twin was also assessed. Meta-analyses using individual data random-effects logistic regression and meta-analyses of proportion were used to analyze the data.

RESULTS

Twenty-two studies (10 877 twin pregnancies) were included in the analysis. In DC pregnancies, a higher risk of IUD, but not of NND, was observed in twins with BW discordance ≥ 15% (odds ratio (OR) 9.8, 95% CI, 3.9-29.4), ≥ 20% (OR 7.0, 95% CI, 4.15-11.8), ≥ 25% (OR 17.4, 95% CI, 8.3-36.7) and ≥ 30% (OR 22.9, 95% CI, 10.2-51.6) compared with those without weight discordance. For each cut-off of BW discordance explored in DC pregnancies, the smaller twin was at higher risk of mortality compared with the larger one. In MC twin pregnancies, excluding cases affected by twin-twin transfusion syndrome, twins with BW discordance ≥ 20% (OR 2.8, 95% CI, 1.3-5.8) or ≥ 25% (OR 3.2, 95% CI, 1.5-6.7) were at higher risk of IUD, compared with controls. MC pregnancies with ≥ 25% weight discordance were also at increased risk of NND (OR 4.66, 95% CI, 1.8-12.4) compared with those with concordant weight. The risk of IUD was higher when considering discordant pregnancies involving at least one SGA fetus. The overall risk of mortality in MC pregnancies was similar between the smaller and larger twin, except in those with BW discordance ≥ 20%.

CONCLUSION

DC and MC twin pregnancies discordant for fetal growth are at higher risk of IUD but not of NND compared with pregnancies with concordant BW. The risk of IUD in BW-discordant DC and MC twins is higher when at least one fetus is SGA. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Accuracy of Predicting Fetal Loss in Twin Pregnancies Using Gestational Age-Dependent Weight Discordance Cut-Offs: Analysis of the STORK Multiple Pregnancy Cohort

Objectives: A third-trimester fetal weight discordance of 25% has been proposed as an independent predictor of fetal loss in twin pregnancies. As fetal weight gain at this stage of pregnancy increases exponentially, it is not entirely certain whether a single cut-off for inter-twin weight discordance is appropriate. The aim of this study was to investigate whether a single weight discordance cut-off can be used or whether different cut-offs should be adopted according to the gestational age at assessment. Methods: This was a retrospective study of all twin pregnancies of known chorionicity from a large regional cohort over a 10-year period. Receiver operating characteristic curve and logistic regression analyses were used to explore the relation between estimated fetal weight (EFW) discordance detected within 4 weeks from the occurrence of the outcome and single fetal loss at different gestational age windows. Results: 957 twin pregnancies (173 monochorionic and 784 dichorionic) were included in the analysis. EFW discordance was independently associated with the occurrence of single fetal loss in twin pregnancies in each gestational age window. Ultrasound EFW discordance had an area under the curve of 0.77 (95% CI: 0.67-0.87) for the prediction of single fetal loss in the third trimester of pregnancy, with an optimal cut-off of around 25% (23.2%). The optimal cut-offs of EFW discordance for the prediction of single fetal loss were different in each gestational age window. Conclusion: The accuracy of EFW discordance in predicting single fetal loss in twin pregnancies varies during the third trimester of pregnancy. The degree of fetal weight discordance associated with fetal loss decreases during the third trimester, suggesting that the weight discordance threshold for intervention should vary according to gestational age.

[Birth weight discordance in dichorionic twins: diagnosis, obstetrical and neonatal prognosis]

OBJECTIVE

To describe neonatal and obstetrical prognosis in dichorionic (DC) twins with a birth weight discordance under 20% and evaluate the influence of intrauterine growth restriction on the management.

PATIENTS AND METHODS

We studied retrospectively 67 DC twins birth between July 2002 and July 2012 at our university labour ward. Birth weight discordance was considered slight between 20-25%, moderate between 25-30%, and severe over 30%.

RESULTS

Prevalence of birth weight discordance in DC twins is estimated at 11.4% in our study. Eighty percent of severe discordance was diagnosed before delivery, 41% for moderate discordance and 20% for slight discordance. We note 30% of pre eclampsia in our population with 44% in the severe discordance group. Mean gestational age was 35.1 weeks for slight and moderate discordances, and 33 weeks for severe discordance. Caesarean section rate was 48% for severe discordance and only 36% for slight discordance. Vaginal delivery rate is 56.7%. More than half of patient with a severe discordance gave birth vaginally. Intrauterine growth restriction rate under the 10th percentile was 18.7%. Prevalence of IUGR was 24% in sever discordance group, 23.5% in the moderate discordance group and 10% in the slight group. Neonatal morbidity rate was 20.8% mainly in children with IUGR.

DISCUSSION AND CONCLUSION

Neonatal mortality and morbidity rate are mainly increased in severe discordant twins. These pregnancies are at high risk of maternal morbidity. Vaginal delivery must be preferred for slight and moderate discordances. In case of severe discordance, vaginal delivery should be considered depending on the degree of intrauterine growth retardation.

Second-trimester discordance and adverse perinatal outcome in twins: the STORK multiple pregnancy cohort

OBJECTIVE

The aim of this study was to determine the association between biometry discordance at the time of the anomaly scan and adverse perinatal outcomes in twin pregnancies.

DESIGN

Retrospective cohort study.

SETTING

Nine hospitals in the Southwest Thames Region of London Obstetric Research Collaborative (STORK).

POPULATION OR SAMPLE

Population multicentre retrospective study of all twin pregnancies booked for antenatal care in nine hospitals over a period of 10 years. Methods Logistic regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate the association between abdominal circumference (AC) and estimated fetal weight (EFW) discordance, recorded between 20 and 22 weeks of gestation, and adverse pregnancy outcomes.

MAIN OUTCOME MEASURES

Stillbirth, neonatal mortality, preterm birth (PTB) at <34 weeks of gestation, and birthweight (BW) discordance ≥25%.

RESULTS

A total of 2399 twin pregnancies [457 monochorionic (MC) and 1942 dichorionic (DC)] were included in the study. The predictive accuracy of the EFW discordance was poor for fetal loss after 22 weeks of gestation (area under the curve, AUC 0.54, 95% CI 0.46-0.64), fetal loss beyond 28 weeks of gestation (AUC 0.42, 95% CI 0.31-0.52), perinatal loss (AUC 0.51, 95% CI 0.44-0.57), BW discordance (AUC 0.63, 95% CI 0.56-0.65), and PTB before 34 weeks of gestation (AUC 0.52, 95% CI 0.49-0.55). There was no significant difference in the prediction of these outcomes when using EFW discordance or AC discordance.

CONCLUSIONS

Once structural malformations, chromosomal abnormalities, and twin-to-twin transfusion syndrome have been excluded, second-trimester EFW and AC discordance have poor predictive value for adverse perinatal outcomes in twin pregnancy.

Crown-rump length discordance and adverse perinatal outcome in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort

OBJECTIVE

Evidence for the role of first-trimester ultrasound in predicting outcome in twin pregnancies is conflicting. The aim of this study was to determine the association between crown-rump length (CRL) discordance and adverse perinatal outcome in twin pregnancies.

METHODS

This was a retrospective study of all twin pregnancies of known chorionicity from a large regional cohort over a 10-year period. Terminations of pregnancy, cases with fetal or chromosomal abnormalities and monoamniotic pregnancies were excluded. Receiver-operating characteristics (ROC) curve and logistic regression analyses were performed to evaluate the association between CRL discordance and stillbirth, neonatal mortality, intrauterine growth restriction, preterm birth (PTB) at < 34 weeks' gestation and birth weight (BW) and ultrasound estimated fetal weight (EFW) discordance of ≥ 25%.

RESULTS

A total of 2155 twin pregnancies were analyzed, of which 420 were monochorionic (MC) and 1735 dichorionic (DC). There were 42 fetal losses before 24 weeks' gestation and 23 perinatal deaths. CRL discordance was poorly predictive for fetal loss at < 24 weeks (area under the ROC curve (AUC), 0.54 (95% CI, 0.46-0.62)), perinatal loss (AUC, 0.52 (95% CI, 0.41-0.64)), BW discordance (AUC, 0.61 (95% CI, 0.56-0.65)), BW < 5(th) centile (AUC, 0.56 (95% CI, 0.53-0.59)), EFW discordance (AUC, 0.55 (95% CI, 0.51-0.60)) and PTB at < 34 weeks (AUC, 0.50 (95% CI, 0.47-0.54)). Overall mortality was significantly higher in MC (5.0%) than in DC (2.6%) twins (P = 0.016). Logistic regression analysis demonstrated that chorionicity (odds ratio 2.09 (95% CI, 1.06-4.10); P = 0.033) independently contributed to determining mortality, while CRL discordance (P = 0.201) did not. Adjusting for chorionicity did not improve the detection of adverse outcomes using CRL discordance.

CONCLUSION

In the absence of aneuploidy or structural fetal abnormality, CRL discordance is of poor predictive value for adverse perinatal outcome in both MC and DC twin pregnancies. CRL discordance should not be used routinely to identify twin pregnancies at high risk of adverse perinatal outcome.

Weight discordance and perinatal mortality in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort

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 of perinatal 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 in twins 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.

Evaluating 2 Year Outcome in Twins ≤ 30 Weeks Gestation at Birth: A Regional Perinatal Unit's Experience

With improved technology in assisted reproductive medicine, there has been an absolute increase in the numbers of twin pregnancies with an associated increase in perinatal mortality and morbidity. This increase in perinatal mortality and morbidity is largely due to a higher incidence of delivering preterm as compared to singletons. Twin pregnancies have their unique complications that include abnormal placental communication and discordant growth which are associated with perinatal mortality and morbidity. The objectives of this study were two-fold: i) to determine if the morbidity/mortality outcome at 18–24 months corrected age seen in a cohort of twins born between 24–30 weeks gestation was significantly different as compared to singleton preterm infants of the same gestation; and ii) to determine and evaluate any differences between monochorionic (MC) and dichorionic (DC) twins. Twins 24–30 weeks gestation at birth born between 01/01/97–30/06/99 were identified and prospectively followed to 18–24 months corrected age (c.a.). They were matched with a singleton infant of the same gender and within 1 week of the same gestation. Obstetrical, neonatal and neurodevelopmental data were gathered and analyzed. The primary outcome was death or the presence of a severe neurodevelopmental deficit at 18–24 months corrected age. Of the 56 sets of twins identified, 52 sets were followed prospectively with 101 infants available for matching. In this cohort, twin pregnancies had a lower incidence of pregnancy-induced hypertension and premature rupture of membranes than singletons (p < 0.05). The two groups were comparable in neonatal characteristics. The incidence of death or severe disability was 29.7% in twins vs. 22.8% in singletons (p = 0.337, Fisher's exact test). The major area of deficit was in the cognitive category for both groups, 9.9% vs. 7.9% respectively. MC twins made up 35.6%; DC twins 64.4%. Twin to twin transfusion syndrome (TTTS) occurred in 6.9%. Discordant growth occurred more frequently in MC pregnancies (p = 0.016). MC twins tended to be more premature, lower in birth weight, and experience neonatal morbidity in the form of patent ductus arteriosus and sepsis (p < 0.05) as compared to DC twins. However, the primary outcome of death or severe neurodevelopmental deficit at 18–24 months c.a. was not significantly different between the two groups, 38.9% (MC) vs. 24.6% (DC), (p = 0.173, Fisher's exact test). Neurodevelopmental morbidity or mortality in twins with TTTS was 42%. Mortality and severe neurodevelopmental morbidity were not significantly higher in twins as compared to singletons in this cohort. However, the trend is slightly higher in twins, which may have clinical significance. Though not statistically significant, the incidence of 38.9% in adverse outcome with MC twins may be clinically significant. With the number of twins steadily increasing, further monitoring is required to determine future directions in intervention and research. Early recognition of monochorionicity remains essential to optimize care and neurodevelopment for these infants.

Stillbirth and Bereavement: Guidelines for Stillbirth Investigation

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Preterm twins: what threshold of birth weight discordance heralds major adverse neonatal outcome?

OBJECTIVE

This study was undertaken to establish the optimal threshold of birth weight discordance for prediction of adverse outcome in liveborn, non-malformed preterm twins.

STUDY DESIGN

We accessed a cohort of twin gestations for the period 1990 through 2000 delivered at less than 37.0 weeks' gestation. Adverse neonatal outcome was defined as stillbirth or occurrence of major morbidities.

RESULTS

A total of 335 twin gestations (670 twins) were included, of which 104 (31%) experienced adverse neonatal outcome. The average birth weight discordance was 12.4% +/- 10.6% versus 19.4% +/- 14.8% in those with good versus adverse outcome (P < .001). Birth weight discordance was a significant predictor of adverse neonatal outcome that was independent of gestational age at delivery, small for gestational age, and chorionicity. Receiver operating characteristic curve analysis suggested that optimal thresholds of birth weight discordance for clinical use should take into account gestational age.

CONCLUSION

Birth weight discordance is an independent predictor of adverse neonatal outcome in liveborn, non-malformed preterm twins.

Management of other complications specific to monochorionic twin pregnancies

Monochorionic (MC) twins have a 3-10-fold higher perinatal mortality and morbidity than dichorionic twins. This is largely attributable to their common vascular architecture and the high rate of discordant fetal growth, growth restriction and congenital abnormalities. In the event of a single intrauterine death (IUD), intertwin agonal transfusion results in up to a 38% risk of death and a 46% risk of neurological injury to the co-twin. This chapter addresses the management of complications unique to MC twins. The primary aim of management is to prevent single IUD or, if inevitable, prevent agonal transfusion occurring by vascular occlusive selective feticide. Older fetoscopic techniques have been replaced by the simpler ultrasound-guided techniques of interstitial laser and bipolar cord occlusion. Their application in twin reversed-arterial perfusion sequence has been associated with a 50% reduction of perinatal mortality in the pump twin. Moreover, prophylactic interstitial laser therapy in early pregnancy might obviate the technical and clinical difficulties in the presence of fetal decompensation in later pregnancy. Recent strategies to reduce the high perinatal mortality due to cord entanglement in antenatally diagnosed monoamniotic twins including medical amnioreduction and elective caesarean delivery at 32 weeks, are also discussed.

Etiology and outcome of fetuses with functional heart disease

BACKGROUND

The aim of this study was to assess the etiology and outcome of fetuses with functional heart disease as detected by echocardiography.

METHODS

In total, 51 fetuses (median gestation age of 28.6 weeks) were included. The inclusion criteria were hydrops (n = 14), pericardial effusion (PE; n = 9), tricuspid valve regurgitation (TR; n = 8), hypertrophic cardiomyopathy (HCM; n = 7) and dilated cardiomyopathy (DCM; n = 7). Antenatal management was performed for 17 of 51 fetuses (33%): two abortions, nine digoxin administrations, three thoracocenteses, one pericardial puncture, one blood transfusion and one ascites centesis.

RESULTS

The etiology of functional heart disease was twin pregnancy in 18, fetal lung lesions in five, maternal diabetes in five, fetal anemia in four, extracardiac or chromosomal abnormalities in three, infection in three, teratoma or arteriovenous malformation in four, indomethacin administration in two, endocardial fibroelastosis in two, maternal anaphylaxia in one, idiopathic arterial calcification of infancy (IACI) in one, pregnancy-induced hypertension (PIH) in one, and unknown in two fetuses. There was no significant difference between fetuses with and without treatment (53% vs. 79%; p = 0.06). There were two stillbirths and 12 postnatal deaths (29%). Among 35 surviving infants, 85% were free of symptoms in the follow-up (mean 3.9 years).

CONCLUSIONS

These findings indicate that a functional heart disease in utero is associated with very varying etiology and high mortality. Improved understanding of the hemodynamic findings may lead to treatment that is more successful.

The risk of mortality or cerebral palsy in twins: a collaborative population-based study

The purpose of the paper was to describe demographic and clinical factors associated with fetal or neonatal death or cerebral palsy (CP) in twins. Vital statistics from five populations in the United States and Australia, which included information on CP diagnosed after 1 y of age. Information on zygosity was not available. In 1,141,351 births, 25,772 of whom were twins, significant secular trends from 1980 to 1989 included increasing prevalence of twins, increasing proportion of unlike-sex twins, and increasing maternal age. Overall, twins were at an approximately 5-fold increased risk of fetal death, 7-fold increased risk of neonatal death, and 4-fold increased risk of CP compared with singletons. However, at birth weight <2500 g, twins generally did better than singletons, both with respect to mortality and to CP rates. Second-born twins and twins from same-sex pairs were at increased risk of early death but not of CP. Twins from growth-discordant pairs and twins whose co-twin died were at increased risk of both mortality and CP. The highest rates of CP were in surviving twins whose co-twin was still-born (4.7%), died shortly after birth (6.3%) or had CP (11.8%). In this large data set spanning a 10-y period, overall rates of death or cerebral palsy were higher in twins than singletons, although small twins generally did better than small singletons. Co-twin death was a strong predictor of CP in surviving twins. This risk was the same for same- and different-sex pairs, and observed both for preterm and term infants.

Respiratory distress syndrome and birth order in premature twins

OBJECTIVE

To determine the effect of birth order on respiratory distress syndrome (RDS) in the outcome of twins in a large premature population managed in a modern neonatal intensive care unit.

METHODS

An historical cohort study design was used to analyse the neonatal outcomes of 301 premature liveborn twin sibling pairs of between 23 and 31 weeks gestation from the Australia and New Zealand Neonatal Network 1995 database.

RESULTS

Among the 56 twin sibling pairs who were discordant for RDS, the second twin was affected in 41 cases (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.5 to 5.3). The excess risk of RDS in the second twin increased with gestation and was statistically significant for twins above 29 weeks gestation (OR 4.4, 95% CI 1.6 to 15).

CONCLUSIONS

There is a significant increased risk of RDS associated with being the second born of premature twins, which appears to depend on gestation.

Twin birth weight discordance and risk of preterm birth

OBJECTIVES

Our purpose was to determine whether birth weight discordance is a risk factor for preterm birth of twins, and to further characterize the relationships involved.

STUDY DESIGN

Maternally linked 1978-1990 Missouri birth certificates were used to analyze gestations resulting in live twins. We used contingency tables and multiple logistic regression.

RESULTS

The degree of discordance correlated strongly with risk for live preterm birth but only for discordances >30% and preterm birth at <32 weeks' gestation. Among 9479 pregnancies with discordance <30%, 9.5% ended in birth at <32 weeks' gestation, versus 13.7% of 326 with discordance of 30% to 40% (P =.03) and versus 34.1% of 126 with discordance > or =40% (P <. 001). There were 42 preterm twin births at <32 weeks' gestation with discordances > or =40%. Of these, 51% were attributable to fetal growth restriction and 16% to large size for gestational age in one infant; in 72% the smaller twin was the second born, and in 86% the twins were like sex. The relative association between > or =40% discordance and preterm birth at <32 weeks' gestation was strengthened (final odds ratio, 9.54; P <.0001) in a multivariate model containing other risk factors for delivery at <32 weeks' gestation: black race, either twin small for gestational age, unmarried, teenage mother, number of male fetuses, like fetal sex, education <12 years, nulliparity, and cigarette smoking.

CONCLUSIONS

Twin birth weight discordance has now clearly been demonstrated to be a risk factor for preterm birth. The effect was found particularly with discordances > or =40% before 32 weeks' gestation. Discordance was usually attributable to fetal growth restriction, most often in the second-born twin.

Twin differences and similarities of birthweight and term in the French Romulus population

This study was performed to examine the main characteristics of the French Romulus twin population: zygosity, chorionicity, sex, term and birthweight. A sample of 104 pairs of twins was distinguished by zygosity, chorionicity and sex, and divided into concordant and discordant birthweight groups. Fifty-three % (n = 55) of the fetus pairs studied were born at "ideal term" (35-38 weeks), and 25% (n = 26) were delivered at "preterm" (28-34 weeks). The very preterm (< 28 weeks), and "postterm" (> 38 weeks) represented altogether 22% (n = 23) of the sample. Of the 104 twin pairs, 68% (n = 71) differ by less than 15% in birthweight, and 32% (n = 33) have a birthweight difference higher than 15%. In dizygotic (DZ) pairs females had more tendency to be in the discordant group (p = 0.01) while in monochorionic-monozygotic (MC-MZ) pairs males were more discordant (p = 0.07). We found a significant interaction between sex and zygosity type (p = 0.02). Males had a birthweight difference significantly weaker than that of females in dichorionic-monozygotic (DC-MZ) and DZ twins whereas it was higher than that of females in MC-MZ twins. There were no MZ twin pairs with DC placentation over than 15% birthweight difference. Log linear analysis demonstrated a three-way interaction (p < 0.05) between term type, zygosity type and hypotrophy. Our data indicate that in the group of twins born between 35 and 38 weeks' gestation the crucial question still remains unsettled on how term and birthweight are related to zygotism and/or chorionicity.

Level of anxiety in parents of high-risk premature twins

We attempted to define parental anxiety in a population of parents of high-risk premature twins (mean birth weight 1,493 +/- 227 kg; mean gestational age 33 +/- 3.5 weeks), admitted to III level NICU. We specifically examined the following factors; gestational age of the twins, whether or not the twins had ventilatory support, pulmonary sequelae, major malformations or intra-ventricular hemorrhage, parental gender and highest level of education obtained by the parent. In the immediate pre-discharge period and a month later, a questionnaire (State-Trait Anxiety Inventory) was given to all parents of premature twins presenting for the discharge. The parents of 30 twins entered the study twice, at the discharge of their first twin (mean postnatal age 40 +/- 32 days), and one month later. They included 15 mothers and 11 fathers, aged 33 +/- 5.5 and 33 +/- 4.2 years, and at the second evaluation 11 mothers and 10 fathers, respectively. As case-controls we examined parental anxiety of fifteen consecutive singleton high-risk prematures, with equal gestational age, discharged immediately after. Our results indicate that the parents of high-risk twin and singleton prematures present an elevated, lasting state-trait anxiety level. Pre- and post-discharge parental anxiety is more elevated (not significant) in twinning with respect to the prematurity alone. When assessed separately by parental gender, in both these groups an increased (not significant) anxiety was persistently found in the mothers. We recommend that, although neonatologists generally define the discharge of the high-risk premature based upon the acquired stabilization of vital parameters, they pay special attention to the twin group we have identified which is at increased risk for predischarge parental anxiety.

Factors associated with neonatal hypoglycemia in premature twins and singletons

Twin gestation is associated with higher rate of neonatal hypoglycemia than do singletons. We examined the role of specific risk factors associated with neonatal hypoglycemia of 216 premature twins and 1284 premature singletons, consecutively born in the years 1994-1996 in the Department of Pediatrics of Padua University, Italy. Significantly higher risk of hypoglycemia (Dextrostix < 40 and < 20 mg%) was found in twins vs singletons (54% vs 32%, OR 2.49, CI 1.77-3.56; 19% vs 8%, OR 2.65, CI 1.59-4.19, respectively). Gestational age of 34-37 weeks increased hypoglycemia risk for the premature twins (77% vs 51%, OR 3.20 CI 1.49-6.88). Twin deliveries statistically differed from those of singletons in several perinatal characteristics. More twins were born by cesarean section (85% vs 55%, OR 4.15, CI 2.48-6.95), and the birth weight of twins was much lower related to prematures with BW < 1.0 kg (12% vs 6%, OR 2.06, CI 1.11-3.82) and SGA (20% vs 10%, OR 2.41, CI 1.46-3.98). The risk of twin deliveries was increased at 30-33 weeks gestational age (25% vs 15%, OR 1.84; CI 1.17-2.90). Twins were found to have higher rates of hospitalization (50% vs 40%, OR 1.52, CI 1.04-2.23) and showed an increased risk of cardiorespiratory resuscitation (51% vs 31%, OR 2.36, CI 1.61-3.47), hypothermia (11% vs 4%, OR 3.02, CI 2.33-3.91), BPD (25% vs 19%, OR 2.55, CI 1.10-5.91), and PVL (4% vs 1%, OR 4.08, CI 1.23-13.5). Mortality was found more often (not significant) in premature twins. The risk for intrapartum and early neonatal morbidity was however, mostly reduced in hypoglycemic twins, while it was comparable between smaller or smaller weight discordant twins and larger twins. Similarly, SGA twins, and smaller or smaller weight-discordant twins did not show increased hypoglycemia risk. In conclusion, our findings suggest that the multiple gestation per se is the single most important relative risk factor of hypoglycemia in premature twins.