Does birth weight discordance in preterm twins affect neonatal outcome?

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.

Role of birthweight discordance in preterm twins' outcomes in the Korean neonatal network

BACKGROUND

Twin pregnancies can be complicated by birthweight (BW) discordance. We analyzed the impact of BW discordance on clinical outcomes of very-low-birthweight (VLBW) twins.

METHODS

The study population was preterm infants in the Korean Neonatal Network registry. Multivariate logistic regression analyses were used to determine the contribution of BW discordance on respiratory morbidities and mortality of VLBW infants. Also, we assessed the effect of small for gestational age (SGA) on morbidity and mortality in discordant twins (DTs) and compared separately the clinical outcomes of smaller and larger DTs with different singletons matched for perinatal factors including BW percentile.

RESULTS

A total of 935 twin pairs [1548 concordant twins (CTs) and 322 DTs] were included. BW discordance was associated with increased odds of moderate bronchopulmonary dysplasia, mortality, and composite outcomes. Compared with the CTs, the smaller, but not larger, DTs had greater odds of morbidities and mortality. DTs had higher odds of adverse neonatal outcome when combined with SGA. Meanwhile, DTs had morbidities and mortality similar to singletons matched for BW percentile.

CONCLUSION

BW discordance in VLBW twins adversely affects neonatal mortality or respiratory morbidity which is predominant in smaller DTs. The impact of BW discordance could be increased through SGA.

Assessment of different thresholds of birthweight discordance for early neonatal outcomes: retrospective analysis of 2348 twin pregnancies

Background

The optimal threshold of birthweight discordance (BWD) remains controversial. This study aimed to evaluate the associations between BWD at different thresholds and early neonatal outcomes and to assess their predictive accuracy.

Methods

This was a retrospective cohort study using a birthweight data with the chorionicity information of 2348 liveborn twin pairs at a gestational age of ≥26 weeks, from 2012 to 2018. The percentage of BWD was calculated by dividing the actual birthweight difference by the weight of the larger twin and multiplying by 100. Outcomes of interest included neonatal intensive care unit (NICU) admission, neonatal respiratory distress syndrome (NRDS), ventilator support and a composite outcome combining major morbidities and neonatal death. Logistic regression models were performed to estimate the association between neonatal outcomes and BWD with different thresholds (≥15.0%, ≥20.0%, ≥25% and ≥ 30%). Generalized estimated equation (GEE) models were used to address intertwin correlation. Restrictive cubic spline (RCS) models were established to draw the dose-response relationship between BWD and the odds ratios of outcomes. Clustered receiver operating characteristic (ROC) curve analyses were performed to assess the predictive accuracy.

Results

Of 2348 twin pairs, including 1946 dichorionic twin pairs and 402 monochorionic twin pairs, BWD was significantly associated with NICU admission, regardless of the thresholds used. The incidence of NRDS, ventilator support and the composite outcome were significantly higher when a threshold of ≥20% or greater was chosen. The dose-response relationship showed nonlinear growth in the risk of adverse neonatal outcomes with increasing BWD. ROC analyses showed a low significant AUROC of 0.569 (95% CI: 0.526–0.612) for predicting NICU admission but no significant AUROCs for predicting other outcomes. A BWD of ≥30% provided a moderate increase in the likelihood of NICU admission [positive likelihood ratio (LR⁺) = 5.77].

Conclusion

Although BWD is independently associated with adverse neonatal outcomes, it is not a single predictor for neonatal outcomes given the weak discriminative ability to predict neonatal outcomes. A cutoff of 30% is more practical for risk stratification among twin gestations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04417-4.

The Delphi definition for selective fetal growth restriction may not improve detection of pathologic growth discordance in monochorionic twins

BACKGROUND

A consensus definition of selective fetal growth restriction (sFGR) in monochorionic diamniotic (MCDA) twins was recently proposed following a Delphi procedure involving an international panel of experts. The new definition augments the traditional definition with additional sonographic criteria.

OBJECTIVE

We sought to determine whether the augmentations of the "Delphi definition" identified additional morbidity and mortality compared to a traditional definition. We also sought to determine the benefit of each definition in identifying pathologic growth restriction relative to uncomplicated MCDA twins.

STUDY DESIGN

This is a retrospective analysis of unselected MCDA twins that underwent fortnightly ultrasound surveillance at a single center between 2011 and 2020. Patients with concomitant twin-to-twin transfusion (TTTS) syndrome, twin anemia polycythemia sequence (TAPS) or twin reverse arterial profusion (TRAP) sequence at the time of sFGR diagnosis were excluded. Diagnosis of sFGR by the Delphi definition required either an estimated fetal weight (EFW) < 3^rd percentile or presence of two of the following four observations in the smaller twin: i) EFW < 10^th percentile, ii) EFW discordance > 25%, iii) abdominal circumference < 10^th percentile, iv) umbilical artery pulsatility index (UA PI) > 95^th percentile. Diagnosis by the traditional definition required EFW < 10^th percentile and EFW discordance > 25%. To determine the efficacy of the augmentations in the Delphi definition, three groups were compared: Group I - uncomplicated MCDA twins, Group II - twins with sFGR by the traditional definition (and therefore the Delphi definition), Group III - twins with sFGR solely by the Delphi definition. Demographic characteristics, subsequent development of TTTS or TAPS, pregnancy outcomes and neonatal outcomes were compared.

RESULTS

There were 325 patients with MCDA twins meeting inclusion criteria. Of these, 213 (Group I, 66%) were uncomplicated, 37 (Group II, 11%) met the traditional definition for sFGR, 112 (35%) met the Delphi definition for sFGR with 75 (67%) meeting solely the Delphi definition (Group III). Demographic characteristics were similar between groups. Patients in Group II delivered earlier than uncomplicated twins (32.1 vs. 35.7 wks, p <0.01) and patients in Group III (32.1 vs 35.6, p < 0.01). They were also more likely to have critical UA Doppler abnormalities (38% vs. 4%, p < 0.01) and be delivered for deteriorating fetal status (30% vs. 5%, p < 0.01) compared with patients in group III. Overall, survival was lower in Group II than Groups I and III (89% vs. 96% and 100% respectively, p = 0.04). Composite neonatal morbidity and mortality was also greater in Group II (30%) compared with either Group I (6%, p < 0.01) or Group III (9%, p < 0.01). Rates of composite neonatal morbidity and mortality were similar between Groups I and III (p = 0.28).

CONCLUSIONS

Addition of AC and PI UA thresholds, as well as isolated EFW < 3% for diagnosis of sFGR, as proposed by the Delphi definition, increased diagnosis of sFGR, however there was no added benefit in identification of growth discordant pregnancies at risk for adverse outcomes. Prospective analysis of MCDA twins is required to contextualize these findings.

Multifetal Gestations: Twin, Triplet, and Higher-Order Multifetal Pregnancies: ACOG Practice Bulletin, Number 231

The incidence of multifetal gestations in the United States has increased dramatically over the past several decades. For example, the rate of twin births increased 76% between 1980 and 2009, from 18.9 to 33.3 per 1,000 births (1). However, after more than three decades of increases, the twin birth rate declined 4% during 2014-2018 to 32.6 twins per 1,000 total births in 2018 (2). The rate of triplet and higher-order multifetal gestations increased more than 400% during the 1980s and 1990s, peaking at 193.5 per 100,000 births in 1998, followed by a modest decrease to 153.4 per 100,000 births by 2009 (3). The triplet and higher-order multiple birth rate was 93.0 per 100,000 births for 2018, an 8% decline from 2017 (101.6) and a 52% decline from the 1998 peak (193.5) (4). The long-term changes in the incidence of multifetal gestations has been attributed to two main factors: 1) a shift toward an older maternal age at conception, when multifetal gestations are more likely to occur naturally, and 2) an increased use of assisted reproductive technology (ART), which is more likely to result in a multifetal gestation (5). A number of perinatal complications are increased with multiple gestations, including fetal anomalies, preeclampsia, and gestational diabetes. One of the most consequential complications encountered with multifetal gestations is preterm birth and the resultant infant morbidity and mortality. Although multiple interventions have been evaluated in the hope of prolonging these gestations and improving outcomes, none has had a substantial effect. The purpose of this document is to review the issues and complications associated with twin, triplet, and higher-order multifetal gestations and present an evidence-based approach to management.

Ultrasound for diagnosis of birth weight discordance in twin pregnancies

BACKGROUND

There is a need to standardize monitoring in obstetric research of twin pregnancies. Identification of birth weight discordance (BWD), defined as a difference in the birth weights of twins, is a well-documented phenomenon in twin pregnancies. Ultrasound for the diagnosis of BWD informs complex decision making including whether to intervene medically (via laser photo coagulation) or deliver the twins to avoid fetal morbidities or even death. The question is, how accurate is this measurement?

OBJECTIVES

To determine the diagnostic accuracy (sensitivity and specificity) of ultrasound estimated fetal weight discordance (EFWD) of 20% and 25% using different estimated biometric ultrasound measurements compared with the actual BWD as the reference standard in twin pregnancies.

SEARCH METHODS

The search for this review was performed on 15 March 2019. We searched CENTRAL, MEDLINE (Ovid), Embase (Ovid), seven other databases, conference proceedings, reference lists and contacted experts. There were no language or date restrictions applied to the electronic searches, and no methodological filters to maximize sensitivity.

SELECTION CRITERIA

We selected cohort-type studies with delayed verification that evaluated the accuracy of biometric measurements at ultrasound scanning of twin pregnancies that had been proposed for the diagnosis of estimated BWD, compared to BWD measurements after birth as a reference standard. In addition, we only selected studies that considered twin pregnancies and applied a reference standard for EFWD for the target condition of BWD.

DATA COLLECTION AND ANALYSIS

We screened all titles generated by electronic database searches. Two review authors independently assessed the abstracts of all potentially relevant studies. We assessed the identified full papers for eligibility, and extracted data to create 2 × 2 tables. Two review authors independently performed quality assessment using the QUADAS-2 tool. We excluded studies that did not report data in sufficient detail to construct 2 × 2 tables, and where this information was not available from the primary investigators. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 39 eligible studies with a median study sample size of 140. In terms of risk of bias, there were many unclear statements regarding patient selection, index test and use of proper reference standard. Twenty-one studies (53%) were of methodological concern due to flow and timing. In terms of applicability, most studies were of low concern. Ultrasound for diagnosis of BWD in twin pregnancies at 20% cut-off Twenty-two studies provided data for a BWD of 20% and the summary estimate of sensitivity was 0.51 (95% CI 0.42 to 0.60), and the summary estimate of specificity was 0.91 (95% CI 0.89 to 0.93) (8005 twin pregnancies; very low-certainty evidence). Ultrasound for diagnosis of BWD in twin pregnancies at 25% cut-off Eighteen studies provided data using a BWD discordance of 25%. The summary estimate of sensitivity was 0.46 (95% CI 0.26 to 0.66), and the summary estimate of specificity was 0.93 (95% CI 0.89 to 0.96) (6471 twin pregnancies; very low-certainty evidence). Subgroup analyses were possible for both BWD of 20% and 25%. The diagnostic accuracy did not differ substantially between estimation by abdominal circumference and femur length but femur length had a trend towards higher sensitivity and specificity. Subgroup analyses were not possible by sex of twins, chorionicity or gestational age due to insufficient data.

AUTHORS' CONCLUSIONS

Very low-certainty evidence suggests that EFWD identified by ultrasound has low sensitivity but good specificity in detecting BWD in twin pregnancies. There is uncertain diagnostic value of EFWD; this review suggests there is insufficient evidence to support this index as the sole measure for clinical decision making to evaluate the prognosis of twins with growth discordance. The diagnostic accuracy of other measures including amniotic fluid index and umbilical artery Doppler resistive indices in combination with ultrasound for clinical intervention requires evaluation. Future well-designed studies could also evaluate the impact of chorionicity, sex and gestational age in the diagnostic accuracy of ultrasound for EFWD.

Birth weight discordance in very low birth weight twins: mortality, morbidity, and neurodevelopment

OBJECTIVE

Examine outcomes among birth weight concordant and discordant 401-1500 g twins.

STUDY DESIGN

Twins (n = 8,114) at NICHD Neonatal Research Network (1994-2011) were studied. Discordance (birth weight difference/larger twin birth weight x 100%) was categorized into: ≤ 14, > 14-20, > 20-30, and > 30%. Separate logistic regression models for the smaller and larger infants assessed the adjusted association between discordance and outcomes.

RESULTS

Compared with the smaller twin with ≤ 14% discordance, mortality, necrotizing enterocolitis, severe retinopathy of prematurity, bronchopulmonary dysplasia, and neurodevelopmental impairment or death were highest among the smaller twins with discordance > 30%. The larger twins with discordance > 30% had higher odds of patent ductus arteriosus, moderate-to-severe cerebral palsy, blindness, cognitive and motor scores < 70. Odds of cerebral palsy and blindness were also higher among the larger twins with discordance > 14-20%.

CONCLUSIONS

Discordance > 30% was associated with higher mortality in the smaller twin and higher morbidities among the smaller and larger twins.

Adverse maternal outcomes and birth weight discordance in twin gestation: British Columbia, Canadian data

Objective

The aim of this study was to determine whether twin pregnancies with birth weight discordance were associated with higher rates of maternal morbidities.

Study design

A large retrospective population-based cohort study of twins born in British Columbia, Canada, from 2000 to 2010 was performed. Maternal morbidities and growth discordant were evaluated.

Results

There were 6,328 twin deliveries during the study period. Pregnancies carrying growth-discordant twins had higher frequencies of hypertension disorders, preterm labor, and cesarean delivery compared with growth-concordant twins. They also stayed longer than 3 days in hospital. Multivariate generalized estimating equation modeling found higher odds of preeclampsia, pregnancy-induced hypertension, preterm delivery, and cesarean delivery in mothers carrying growth-discordant twins compared with those carrying growth-concordant category. The modeling also resulted in higher odds in the length of stay longer than 3 days in mothers carrying growth-discordant twins compared with those carrying growth-concordant twins after adjustment for chorionicity.

Conclusion

Maternal complications are associated with growth discordance. Screening for birth weight discordance during pregnancy may alert clinicians to predict subclinical maternal conditions.

[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.

Hypoglycemia in critically ill children

BACKGROUND

The practice of glycemic control with intravenous insulin in critically ill patients has brought clinical focus on understanding the effects of hypoglycemia, especially in children. Very little is published on the impact of hypoglycemia in this population. We aimed to review the existing literature on hypoglycemia in critically ill neonates and children.

METHODS

We performed a systematic review of the literature up to August 2011 using PubMed, Ovid MEDLINE and ISI Web of Science using the search terms "hypoglycemia or hypoglyc*" and "critical care or intensive care or critical illness". Articles were limited to "all child (0-18 years old)" and "English".

RESULTS

A total of 513 articles were identified and 132 were included for review. Hypoglycemia is a significant concern among pediatric and neonatal intensivists. Its definition is complicated by the use of a biochemical measure (i.e., blood glucose) for a pathophysiologic problem (i.e., neuroglycopenia). Based on associated outcomes, we suggest defining hypoglycemia as <40-45 mg/dl in neonates and <60-65 mg/dl in children. Below the suggested threshold values, hypoglycemia is associated with worse neurological outcomes, increased intensive care unit stay, and increased mortality. Disruptions in carbohydrate metabolism increase the risk of hypoglycemia incritically ill children. Prevention of hypoglycemia, especially in the setting of intravenous insulin use, will be best accomplished by the combination of accurate measuring techniques, frequent or continuous glucose monitoring, and computerized insulin titration protocols.

CONCLUSION

Studies on hypoglycemia in critically ill children have focused on spontaneous hypoglycemia. With the current practice of maintaining blood glucose within a narrow range with intravenous insulin, the risk factors and outcomes associated with insulin-induced hypoglycemia should be rigorously studied to prevent hypoglycemia and potentially improve outcomes of critically ill children.

Differences in short-term neonatal outcomes between discordant twins

PURPOSE

To evaluate short-term outcomes associated with discordant twin pairs admitted to the NICU.

DESIGN

A retrospective descriptive study comparing discordant twin pairs.

SUBJECTS

Three hundred eighty-four discordant twin pairs were included. Mean gestational age of the twin pairs was 32.6 weeks (range, 24-39).

METHODS

The ParadigmHealth database was queried for all twin admissions from January 2001 to June 2004 admitted to 453 NICUs across the United States. Discordance was calculated for each twin set as defined as greater than 20% difference in birth weight. Exclusion criteria were death of a twin, congenital anomalies, or extracorporeal life support.

MAIN OUTCOME MEASURES

Demographics, respiratory needs, feeding characteristics, complications, and discharge needs.

RESULTS

A total of 384 discordant twin pairs met inclusion criteria. The larger twins required more ventilation/continuous positive airway pressure (55% vs 44%, P < .01) and/or oxygen therapy (50% vs 41%, P = .02) compared with smaller twins. Smaller twins reached full oral (PO) feeds an average of 0.6 weeks later than larger twins (P < .0001) but had more weight gain per day. Smaller twins transitioned to an open crib at lower weights but at slightly greater age. No differences were noted with necrotizing enterocolitis or apnea. Smaller twins had increased nosocomial infections. Mean length of stay was shorter (P = .0036) in the larger twin group. Only 33% of the twin pairs were discharged on the same day.

CONCLUSIONS

Larger twins had more acute respiratory issues but achieved certain milestones more rapidly with fewer complications, thus leading to earlier discharge compared with their smaller twin counterparts.