Twinning on the brain: the effect on neurodevelopmental outcomes

Chorionicity and Psychomotor Development From Infancy to Childhood: The Japan Environment and Children's Study

Twins lag behind singletons in their early psychomotor development, but little is known about how chorionicity affects this difference. We compared early psychomotor development in singletons, monochorionic (MC) twins and dichorionic (DC) twins. Our longitudinal data from the Japan Environment and Children's Study (JECS; see Appendix) included 98,042 singletons, 577 MC twins and 1051 DC twins representing the general Japanese population. Chorionicity was evaluated by ultrasound images and complemented by postnatal pathological examinations. Five domains of psychomotor development were evaluated at 6 time points from 6 months to 3 years of age using the Ages and Stages Questionnaires (ASQ-3). The data were analyzed using linear regression models. Twins lagged behind singletons in all areas of psychomotor development during infancy. This gap decreased over time but was still noticeable at 3 years of age. More than half of this difference was attributed to twins having lower birth weight and being born earlier in gestation. MC twins showed slightly delayed development compared to DC twins, but this difference was minor compared to the overall gap between twins and singletons. Twins delay singletons in their early psychomotor development, and this delay is not specific to MC twinning.

Cerebral palsy and related neuromotor disorders: Overview of genetic and genomic studies

Cerebral palsy (CP) is a debilitating condition characterized by abnormal movement or posture, beginning early in development. Early family and twin studies and more recent genomic investigations clearly demonstrate that genetic factors of major effect contribute to the etiology of CP. Most copy number variants and small alterations of nucleotide sequence that cause CP arise as a result of de novo mutations, so studies that estimate heritability on basis of recurrence frequency within families substantially underestimate genetic contributions to the etiology. At least 4% of patients with typical CP have disease-causing CNVs, and at least 14% have disease-causing single nucleotide variants or indels. The rate of pathogenic genomic lesions is probably more than twice as high among patients who have atypical CP, i.e., neuromotor dysfunction with additional neurodevelopmental abnormalities or malformations, or with MRI findings and medical history that are not characteristic of a perinatal insult. Mutations of many different genetic loci can produce a CP-like phenotype. The importance of genetic variants of minor effect and of epigenetic modifications in producing a multifactorial predisposition to CP is less clear. Recognizing the specific cause of CP in an affected individual is essential to providing optimal clinical management. An etiological diagnosis provides families an "enhanced compass" that improves overall well-being, facilitates access to educational and social services, permits accurate genetic counseling, and, for a subset of patients such as those with underlying inherited metabolic disorders, may make precision therapy that targets the pathophysiology available. Trio exome sequencing with assessment of copy number or trio genome sequencing with bioinformatics analysis for single nucleotide variants, indels, and copy number variants is clinically indicated in the initial workup of CP patients, especially those with additional malformations or neurodevelopmental abnormalities.

Imaging diagnosis and legal implications of brain injury in survivors following single intrauterine fetal demise from monochorionic twins - a review of the literature

Brain injury of the surviving twin from monochorionic pregnancies following intrauterine fetal demise during the second and third trimesters is a rare but severe complication. Monochorionicity and gestational age at the time of stillbirth seem to be decisive factors in terms of long-term neurologic outcome prediction for the survivor. Magnetic resonance imaging (MRI), diffusion weighted imaging (DWI) in particular, seem to bring the earliest and most accurate diagnosis. Ultrasound detection of brain damage is possible in later stages of fetal brain injury. It is essential to provide early diagnosis and multidisciplinary counsel to the parents to ensure informed decision making. For couples who choose to terminate pregnancy legislation related to late abortion might lead to further distress. Our paper aims to stress the importance of MRI DWI in the evaluation of surviving twins following single intrauterine fetal demise in monochorionic pregnancies and the delicate context of the medical professionals and parents facing this clinical situation, sometimes complicated by legal constraints.

The spectrum of brain malformations and disruptions in twins

Twins have an increased risk for congenital malformations and disruptions, including defects in brain morphogenesis. We analyzed data on brain imaging, zygosity, sex, and fetal demise in 56 proband twins and 7 less affected co-twins with abnormal brain imaging and compared them to population-based data and to a literature series. We separated our series into malformations of cortical development (MCD, N = 39), cerebellar malformations without MCD (N = 13), and brain disruptions (N = 11). The MCD group included 37/39 (95%) with polymicrogyria (PMG), 8/39 (21%) with pia-ependymal clefts (schizencephaly), and 15/39 (38%) with periventricular nodular heterotopia (PNH) including 2 with PNH but not PMG. Cerebellar malformations were found in 19 individuals including 13 with a cerebellar malformation only and another 6 with cerebellar malformation and MCD. The pattern varied from diffuse cerebellar hypoplasia to classic Dandy-Walker malformation. Brain disruptions were seen in 11 individuals with hydranencephaly, porencephaly, or white matter loss without cysts. Our series included an expected statistically significant excess of monozygotic (MZ) twin pairs (22/41 MZ, 54%) compared to population data (482/1448 MZ, 33.3%; p = .0110), and an unexpected statistically significant excess of dizygotic (DZ) twins (19/41, 46%) compared to the literature cohort (1/46 DZ, 2%; p < .0001. Recurrent association with twin-twin transfusion syndrome, intrauterine growth retardation, and other prenatal factors support disruption of vascular perfusion as the most likely unifying cause.

Advances in cerebral palsy biomarkers

Cerebral palsy (CP), defined as a group of nonprogressive disorders of movement and posture, is the most common cause of severe neurodisability in children. The prevalence of CP is the same across the globe, affecting approximately 17 million people worldwide. Cerebral Palsy is an umbrella term used to describe the disease due to its inherent heterogeneity. For instance, CP has multiple (1) causes; (2) clinical types; (3) patterns of neuropathology on brain imaging and (4) it's associated with several developmental pathologies such as intellectual disability, autism, epilepsy, and visual impairment. Understanding its physiopathology is crucial to developing protective strategies. Despite its importance, there is still insufficient progress in the areas of CP prediction, early diagnosis, treatment, and prevention. Herein we describe the current risk factors and biomarkers used for the diagnosis and prediction of CP. With the advancement in biomarker discovery, we predict that our understanding of the etiopathophysiology of CP will also increase, lending to more opportunities for developing novel treatments and prognosis.

The complex aetiology of cerebral palsy

Cerebral palsy (CP) is the most prevalent, severe and costly motor disability of childhood. Consequently, CP is a public health priority for prevention, but its aetiology has proved complex. In this Review, we summarize the evidence for a decline in the birth prevalence of CP in some high-income nations, describe the epidemiological evidence for risk factors, such as preterm delivery and fetal growth restriction, genetics, pregnancy infection and other exposures, and discuss the success achieved so far in prevention through the use of magnesium sulfate in preterm labour and therapeutic hypothermia for birth-asphyxiated infants. We also consider the complexities of disentangling prenatal and perinatal influences, and of establishing subtypes of the disorder, with a view to accelerating the translation of evidence into the development of strategies for the prevention of CP.

Neurodevelopmental Outcomes of Twins Compared With Singleton Children: A Systematic Review

More than 200 million children aged <5 years fail to reach their full cognitive potential, and children born as twins are particularly at risk. In this article, we review studies that examined differences in the neurodevelopmental outcomes of twins compared to singletons. We searched the Medline database for articles on twins, singletons, neuro, and cognitive development. We also inspected bibliographies of relevant publications to identify related articles from 2011 to 2017. Our search criteria yielded 162 studies, 8 of which met the inclusion criteria. Of the eight studies examined, four were prospective follow-up studies, three were cross-sectional studies, and one was a randomized controlled trial. Five of these studies were carried out in developed countries, and they found no statistically significant difference in neurodevelopmental outcomes among twins and singletons. However, two of the three studies carried out in developing countries found a difference with singletons having significantly higher academic ratings than twins. Studies in which neurodevelopmental outcomes were measured early in life (1-5 years) showed no significant twin-singleton differences, while those in which it was measured later in life showed mixed twin-singleton differences. Overall, these studies may have been underpowered and may not have been optimally designed and implemented. There is need for studies with adequate sample sizes, good design, and optimal measurement of all relevant covariates in order to resolve the conflicting reports in the literature.

Twins and neurodevelopmental outcomes: the effect of IVF, fetal growth restriction, and preterm birth

This invited review aimed at presenting the evidence concerning neurodevelopmental outcomes, particularly cerebral palsy (CP), motor disability, cognitive impairment, mental retardation, any major disability, blindness and deafness in cases of twins, conceived after in vitro fertilization, presenting fetal/intrauterine growth restriction (FGR/IUGR) or being prematurely born. FGR/IUGR, prematurity and zygosity affect neurodevelopmental outcome; CP is higher in term infants, those presenting with FGR/IUGR, as well as in survivors of intrauterine co-twin death; cognitive ability of twins versus singletons mainly relates to confounding factors, as FGR/IUGR and prematurity, while evidence for differences in behavioral and psychiatric disorders between twins and singletons is limited. The impact of IVF per se has not been documented. Nevertheless, available literature, usually of heterogeneous and retrospective nature, diverges in the criteria for neurodevelopmental delay. Furthermore, differences in selection/exclusion criteria and small mixed cohorts, including the full range of complications, make comparison of the existing studies difficult. Future studies should focus in confirming the lack of IVF impact on twins' neurodevelopment and general health, in comparing long-term outcome of naturally conceived twins with those conceived following assisted reproduction techniques and in including evaluation of individual, longitudinal trajectories of growth, and development. In this respect, worldwide population-based registries will enable more precise description of neurodevelopmental outcomes among twins.

Risk of cerebral palsy in Chinese children: A N:M matched case control study

AIM

To estimate epidemiological risk factors for cerebral palsy (CP) in children.

METHODS

A N:M matched case control study was conducted in 114 persons with CP and 1286 controls. Relevant data were collected using a maternal self-design questionnaire. Univariate logistic regression and multivariate conditional logistic regression analyses were performed using SPSS.

RESULTS

Univariate analysis has yielded 20 significant risk factors for CP. Advanced maternal age (30 years or older) at childbirth (adjusted odds ratio (OR) 1.63, 95% confidence interval (CI) 0.98-2.72), alcohol consumption during pregnancy (adjusted OR 4.17, 95% CI 1.23-14.08), living in the countryside (adjusted OR 1.71, 95% CI 1.18-2.48), father's occupational exposure to harmful substances (adjusted OR 3.34, 95% CI 1.61-6.93) and multiple births (adjusted OR 3.10, 95% CI 1.65-5.84) were found to be risk factors for CP by multivariate analysis. On the other side, high mother's education level (adjusted OR 0.60, 95% CI 0.46-0.76), folic acid supplements (adjusted OR 0.50, 95% CI 0.30-0.82), and high birth hospital level (adjusted OR 0.68, 95% CI 0.52-0.90) were found to be protective factors.

CONCLUSION

Although the important risk factors of CP focus on gestation at birth and perinatal events, the incidence could probably be further lowered, if potential risk factors identified in this study are considered.

Neuro-developmental outcome of a large cohort of growth discordant twins

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.

Impact of ART on pregnancies in California: an analysis of maternity outcomes and insights into the added burden of neonatal intensive care

OBJECTIVE

We reviewed the occurrence of prematurity, low birth weight, multiple gestations, frequency of stillbirths and maternity care-associated variables including hospital stay and hospital charges of women conceiving using assisted reproductive technology (ART) or artificial insemination (AI) compared with women with a history of infertility who conceived naturally, and all other naturally conceived pregnancies in California at non-federal hospitals between 2009 and 2011. At a single center, infants born after ART/AI were compared with infants provided care in the normal nursery.

STUDY DESIGN

Publically available inpatient data sets from the California Office of Statewide Health Planning and Development for years 2009-2011 using data from all California non-federal hospitals were used to determine the impact of ART on a variety of pregnancy-related outcomes and infant characteristics. Infant data from a single center was used to determine hospital charges for infants delivered over an 18-month period to compare the hospital and physician charges indexed to similar charges for infants admitted to the 'normal' newborn nursery.

RESULT

Among ART/AI pregnancies, there was a 4-5-fold increase in stillbirths, compared with a 2-3-fold increase among women with infertility compared with other naturally conceiving women. ART/AI pregnancies underwent more cesarean sections (fourfold), and a near fourfold increase in the rate of preterm deliveries. Multiple gestations were increased 24-27-fold compared with naturally conceived pregnancies. Maternal hospital stay and hospital charges were increased among those undergoing ART/AI. Infant charges were increased multi-fold for singletons, twins and triplets delivered after ART/AI compared with naturally conceived infants.

CONCLUSION

Multiple births, preterm births and a higher overall rate of fetal anomalies were found in California after ART/AI for 2009-2011. Cesarean section rates, longer length of maternal stay and hospital charges among women receiving ART/AI could be lowered if emphasis on elective single embryo transfers was a higher priority among providers. Charges for the care of infants delivered after ART/AI are substantially higher than among naturally conceived infants born late preterm or at term. Families seeking ART/AI need to be informed of the impact of these adverse pregnancy outcomes, including neonatal outcomes and charges for medical care for their infant(s), when considering ART/AI.

Impact of ART on pregnancies in California: an analysis of maternity outcomes and insights into the added burden of neonatal intensive care

OBJECTIVE

We reviewed the occurrence of prematurity, low birth weight, multiple gestations, frequency of stillbirths and maternity care-associated variables including hospital stay and hospital charges of women conceiving using assisted reproductive technology (ART) or artificial insemination (AI) compared with women with a history of infertility who conceived naturally, and all other naturally conceived pregnancies in California at non-federal hospitals between 2009 and 2011. At a single center, infants born after ART/AI were compared with infants provided care in the normal nursery.

STUDY DESIGN

Publically available inpatient data sets from the California Office of Statewide Health Planning and Development for years 2009-2011 using data from all California non-federal hospitals were used to determine the impact of ART on a variety of pregnancy-related outcomes and infant characteristics. Infant data from a single center was used to determine hospital charges for infants delivered over an 18-month period to compare the hospital and physician charges indexed to similar charges for infants admitted to the 'normal' newborn nursery.

RESULT

Among ART/AI pregnancies, there was a 4-5-fold increase in stillbirths, compared with a 2-3-fold increase among women with infertility compared with other naturally conceiving women. ART/AI pregnancies underwent more cesarean sections (fourfold), and a near fourfold increase in the rate of preterm deliveries. Multiple gestations were increased 24-27-fold compared with naturally conceived pregnancies. Maternal hospital stay and hospital charges were increased among those undergoing ART/AI. Infant charges were increased multi-fold for singletons, twins and triplets delivered after ART/AI compared with naturally conceived infants.

CONCLUSION

Multiple births, preterm births and a higher overall rate of fetal anomalies were found in California after ART/AI for 2009-2011. Cesarean section rates, longer length of maternal stay and hospital charges among women receiving ART/AI could be lowered if emphasis on elective single embryo transfers was a higher priority among providers. Charges for the care of infants delivered after ART/AI are substantially higher than among naturally conceived infants born late preterm or at term. Families seeking ART/AI need to be informed of the impact of these adverse pregnancy outcomes, including neonatal outcomes and charges for medical care for their infant(s), when considering ART/AI.

Do very preterm twins and singletons differ in their neurodevelopment at 5 years of age?

OBJECTIVE

Twins have inconsistently shown poorer outcomes than singletons. Although a high proportion of twins are born very preterm, data are sparse on the long-term outcomes in very preterm twins. The objective of this study was to compare mortality and neurodevelopmental outcomes of very preterm singletons and twins and to study outcomes in relation to factors specific to twins.

DESIGN

Birth cohort study Etude Epidemiologique sur les Petits Ages Gestationnels (EPIPAGE).

SETTING

Nine regions in France.

PATIENTS

All very preterm live births occurring from 22 to 32 weeks of gestation in all maternity wards of nine French regions in 1997 (n=2773).

MAIN OUTCOMES MEASURES

Neurodevelopmental status, including cerebral palsy, and a cognitive assessment with the Kaufman Assessment Battery for Children, with scores on the Mental Processing Composite (MPC) scale, was available for 1732 and 1473 children at 5 years of age, respectively.

RESULTS

Among live births, twins had higher hospital mortality than singletons (adjusted (a)OR: 1.4 (95% CI 1.1 to 1.9)). Among survivors, there was no crude difference at 5 years between twins and singletons in the prevalence of cerebral palsy (8.0% vs 9.1%, respectively), MPC <70 (9.5% vs 11.1%) and mean MPC (94.6 vs 94.4). However, after adjustment for sex, gestational age, intrauterine growth restriction and social factors, twins were more likely to have lower MPC scores (mean difference: -2.4 (95% CI-4.8 to 0.01)). Live born twins had a higher risk of mortality when birth weight discordance was present (aOR:2.9 (95% CI 1.7 to 4.8)), but there were no differences in long-term outcomes.

CONCLUSIONS

Compared with very preterm singletons, twins had higher mortality, no difference with respect to severe deficiencies, but slightly lower MPC scores at 5 years.

Neonatal mortality and morbidity in preterm infants born from assisted reproductive technologies

AIM

Premature birth is frequent in infants conceived with assisted reproductive technologies (ART). We sought to determine whether neonatal outcome in ART preterm infants differs from that of spontaneously conceived (SC) preterm infants.

METHODS

Data were prospectively collected in infants born ≤ 32 weeks after ART or SC. We calculated a composite index of severe morbidity (based on occurrences of severe necrotizing enterocolitis, severe intraventricular haemorrhage, periventricular leukomalacia or bronchopulmonary dysplasia). Survival rate without severe morbidity was compared between the two groups.

RESULTS

Six hundred and twelve preterm infants were hospitalized in our tertiary care centre: 81 in ART group and 521 in SC group. In the ART group, twin pregnancy (69.1% vs. 15.9%, p < 0.001) and inborn delivery (98.8% vs. 90.0%, p < 0.01) were more frequent. Gestational age (29 vs. 28 weeks, p < 0.05) and birth weight (1100 vs. 1020 g, p < 0.001) were also higher. Survival without severe morbidity was significantly higher in ART infants (76.5% vs. 55.2%, p < 0.001), with the difference mainly observed in infants born ≤ 28 weeks (22.9% vs. 55.7%, p < 0.001).

CONCLUSION

Assisted reproductive technologies was not associated with adverse neonatal outcome. Differences in pregnancy and neonatal characteristics probably explain the increased survival without severe morbidity in ART infants.

Altered fetal cerebral and cerebellar development in twin-twin transfusion syndrome

BACKGROUND AND PURPOSE

Neurodevelopmental disability is common in twins with TTTS in utero; however, the responsible neuropathology remains uncertain. We proposed to document the frequency of brain abnormalities on clinical fetal MR images and to determine if quantitative fetal brain biometric analysis in twin fetuses with TTTS was different from those in healthy control fetuses.

MATERIALS AND METHODS

We reviewed the fetal brain MR images of 33 twin pairs with TTTS clinically evaluated in our institution. Eighteen fetal MR images of "healthy" twins with TTTS were further studied with biometric analysis in comparison with GA-matched singleton fetuses to detect quantitative differences in brain growth and development.

RESULTS

A higher incidence of anomalies (11/33, 33.3%) was found than previously reported. The most frequent abnormality was ventriculomegaly (7/11, 63%) in both donor and recipient. In "healthy" twins with TTTS, biometric analysis revealed persistently small measurements (cBTD, CMT, TCD, and VAPD) in the donor cerebrum and cerebellum in comparison with their recipient cotwin and healthy control fetuses. These differences were preserved when normalized by cBTD.

CONCLUSIONS

Our findings show that significant brain abnormalities are common in TTTS. In addition, diffuse subtle abnormalities are also present in normal-appearing donor fetal brains that cannot be solely explained by overall growth restriction. Such subtle fetal brain anomalies may explain the high incidence of poor long-term neurodevelopmental outcomes of survivors, and they need to be further investigated with more sophisticated quantitative fetal imaging methodologies.

No major effect of twinning on autistic traits

BACKGROUND

It has been questioned whether the process of twinning might be a risk factor for autism spectrum conditions (ASC) and autistic traits.

AIM

We sought to determine whether autistic traits and probable disorder, as measured by the Childhood Autism Spectrum Test (CAST), were more pronounced in twins compared to singletons.

SAMPLES

Data were analyzed from two large population-based samples of UK children, twins (n = 5,142 twin pairs, aged 8 years) and singletons (n = 2,805, aged 5-9 years).

RESULTS

Distributions of CAST scores in both groups were negatively skewed and scores for twins were more variable than singletons. Mean CAST total scores and standard errors (SE) were not significantly different for twins (5.1; SE 0.04) compared to singletons (4.9; SE 0.08). Moreover, contrary to expectations, the likelihood of scoring above the threshold for possible ASC was significantly lower in the twins than the singletons (OR = 0.69; P = 0.002). Subsidiary analyses of CAST scores according to sex, twin type, and subscale scores representing the subdomains of autism found a few significant differences (P<0.01), but the effect sizes for these differences were small and none exceeded η(2) = 0.005. The explanation for these small differences remains obscure, but the very small effect sizes mean they are of little importance.

CONCLUSIONS

Our results do not provide evidence to support twinning as a risk factor in the development of autistic traits.

Oxidative stress in twin neonates is influenced by birth weight and weight discordance

OBJECTIVES

To evaluate the extent of oxidative stress in neonates born from multiple gestation pregnancies who are at high risk of prematurity and growth abnormalities.

DESIGN AND METHODS

Blood samples were collected from umbilical cord of 72 twins, born at gestational age of 28-38 weeks, and 20 consecutive control singletons. Oxidative stress parameters (15-F(2t)-isoprostane, a marker of lipid peroxidation, and total antioxidant capacity, tAOC), were measured in cord plasma.

RESULTS

Levels of 15-F(2t)-isoprostane showed a moderate negative correlation with birth weight and were higher in small co-twins of discordant pairs; tAOC was positively correlated with birth weight but no significant difference was found between co-twins.

CONCLUSIONS

Oxidative stress levels in twins are mainly influenced by birth weight and weight discordance. We suggest that evaluation of cord blood 15-F(2t)-isoprostane might be of clinical value as maker of pre- and perinatal distress in twinning.

Single twin demise: consequence for survivors

Multiple pregnancies, the majority of which are twins, are at substantially higher risk of fetal morbidity and mortality when compared with singleton pregnancies. Single fetal demise occurs in up to 6.2% of all twin pregnancies. It may cause considerable risk for the co-twin including increased risk of fetal loss, premature delivery, neurovascular injury and end-organ damage. In this review we seek to summarise the most contemporary literature on the aetiology of single twin demise, the pathophysiology of injury to the surviving twin and the evidence for current management strategies.