Reduced lung function during childhood in identical twins with discordant fetal growth: a cohort study

Background

Fetal growth restriction (FGR) can negatively affect lung development, leading to increased respiratory morbidity and reduced lung function later in life. Studies regarding the impact of FGR on lung function in singletons are influenced by genetic, obstetric, and maternal factors. To overcome these confounding factors, we aim to investigate lung function in identical twins with selective FGR (sFGR).

Methods

Lung function assessments were performed in identical twins with sFGR born in our centre between March 1, 2002, and December 31, 2017, aged between 5 and 17 years. sFGR was defined as birthweight discordance ≥20%. Outcome measures consisted of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and transfer factor for carbon monoxide (DLCO) and were compared between the smaller and larger twin.

Findings

Thirty-nine twin pairs performed spirometry of sufficient quality. Median gestational age at birth was 34.3 (interquartile range (IQR) 32.1-36.0) weeks with median birthweights of 1500 (IQR 1160-1880) grams and 2178 (IQR 1675-2720) grams for the smaller and larger twin, respectively. Smaller twins had significantly lower z-scores for FEV1 (-0.94 versus -0.41, p = 0.0015), FVC (-0.56 versus -0.06, p < 0.0001) and DLCO (-0.50 versus 0.00, p < 0.0001) compared to larger co-twins.

Interpretation

Although being genetically identical, sFGR in identical twins is associated with a reduction in static and dynamic lung volume and a reduction in lung diffusion, even when taking the reduced lung volume into account. This indicates that adverse growth conditions in utero negatively affect lung development and function, potentially contributing to an increase in respiratory morbidities later in life.

Funding

The Dutch Heart Foundation and The Bontius Foundation.

Necrotizing enterocolitis in monochorionic twins: Insights from an identical twin model

Necrotizing enterocolitis (NEC) is a major cause of neonatal morbidity and mortality in preterm neonates, yet its pathophysiology remains unclear. The aim of this study is to evaluate risk factors for NEC using an identical twin model. In this case-control study, all monochorionic twin pairs born in our center in 2002-2020 were retrospectively reviewed for NEC. Potential risk factors for NEC were studied. For within-pair comparison, outcomes were compared between affected and unaffected twins. Within-pair analyses showed that the twin with NEC had a lower birth weight compared to its unaffected co-twin (1100 (913-1364) vs. 1339 (1093-1755) grams). Median gestational age at birth and birth weight were lower in twin pairs in the NEC-group compared to the no-NEC group, 29.1 weeks (27.8-30.8) versus 33.6 (30.7-36.0) and 1221 g (1010-1488) versus 1865 (1356-2355) respectively. Twin pregnancies in the NEC-group were more often complicated by twin-to-twin transfusion syndrome compared to the no-NEC-group (70 % (14/20) vs. 49 % (472/962)), particularly when treated with amnioreduction. This unique population of identical twins confirms that preterm neonates with a relatively lower birth weight are more prone to develop NEC compared to their co-twin, regardless of other genetic, maternal and obstetrical factors.

Artery-to-vein anastomoses in unequally divided placentas and their association with birthweight discordance

INTRODUCTION

This study investigated the impact of the shared intertwin circulation in unequally divided monochorionic (MC) placentas on fetal growth.

METHODS

This retrospective analysis included color-dyed, unequally shared placentas from two tertiary centers. Exclusions included twin-twin transfusion syndrome, twin anemia polycythemia sequence, and lethal anomalies. Measurement of the external diameters and areas of the artery-to-artery (AA), artery-to-vein (AV), and vein-to-vein (VV) anastomoses was performed. The ratio of the shared circulation (AV ratio) was determined by comparing the areas of the summed venous components of shared AV anastomoses to those in the individual AV anastomoses of the smaller placental part. The birth weight ratio/placental ratio (BWR/PR), total AV size areas and net AV transfusion were calculated. Univariable and multivariable linear regressions were performed to assess the relationship between BWR/PR, the AV ratio, the areas of the different anastomoses and cord insertion discordance.

RESULTS

Among 352 placentas, 97 % (340) had intertwin AV anastomoses, and 50 % (176) were from pregnancies with selective growth restriction. The AV ratio, AA, VV, total AV areas, and cord insertion discordance negatively correlated with BWR/PR. Multivariable linear regression confirmed the independent negative association between BWR/PR and the AV ratio, suggesting that a larger shared circulation benefits the twin with the smaller placental part. Type III sFGR placentas exhibited the highest AV ratio, resulting in the lowest BWR/PR.

DISCUSSION

A larger shared circulation mitigates the impact of an unequally divided placenta on fetal growth. This effect surpasses the influence of AA and VV diameters and is most prominent in Type III sFGR placentas.

Association between fetal growth-restriction and retinopathy of prematurity using a unique identical twin model

BACKGROUND

Research in singletons identified fetal growth restriction (FGR) as a risk factor for retinopathy of prematurity (ROP), but is generally subject to confounding by genetic, obstetric, and maternal factors. We investigated the effect of FGR on ROP in growth-discordant identical twins, thereby controlling for confounding factors.

METHODS

All data of monochorionic (MC) twin pairs with a birth weight discordance ≥20% born in our center between 2010 and 2021 were retrospectively reviewed for the presence of ROP. Potential risk factors for ROP were analyzed. Outcomes were compared between the smaller and larger twin.

RESULTS

We included 88 MC twin pairs with growth discordance. In 34% (30/88), both neonates were at risk of ROP. Prevalence of ROP was higher among the smaller twin compared to the larger twin, 30% (9/30) versus 13% (4/30), respectively (OR 2.8, 95% CI: 1.2-6.6). The smaller twin had a longer duration of mechanical ventilation (8 (1-20) versus 2 (1-4) days) and received their first red blood cell transfusion at an earlier postmenstrual age (29.6 (28.1-31.6) versus 30.4 (29.7-32.6) weeks).

CONCLUSIONS

In this identical twin model, FGR is associated with almost tripled odds of ROP development, suggesting that both unfavorable antenatal growth conditions and adverse neonatal outcomes affect postnatal retinal vascular proliferation.

IMPACT

Fetal growth restriction in growth-discordant identical twins is associated with almost tripled odds of developing retinopathy of prematurity in the smaller twin. Since these twins do not only differ in birth weight but also duration of mechanical ventilation and timing of the first red blood cell transfusion, both unfavorable antenatal growth conditions and adverse neonatal outcomes can affect postnatal retinal vascular proliferation. More attention for preventing retinopathy of prematurity is needed in those with fetal growth restriction who received prolonged duration of mechanical ventilation, oxygen supplementation, or a first red blood cell transfusion <32 weeks postmenstrual age.

A robust and standardized method to isolate and expand mesenchymal stromal cells from human umbilical cord

BACKGROUND AIMS

Human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) are increasingly used in research and therapy. To obtain hUC-MSCs, a diversity of isolation and expansion methods are applied. Here, we report on a robust and standardized method for hUC-MSC isolation and expansion.

METHODS

Using 90 hUC donors, we compared and optimized critical variables during each phase of the multi-step procedure involving UC collection, processing, MSC isolation, expansion and characterization. Furthermore, we assessed the effect of donor-to-donor variability regarding UC morphology and donor attributes on hUC-MSC characteristics.

RESULTS

We demonstrated robustness of our method across 90 UC donors at each step of the procedure. With our method, UCs can be collected up to 6 h after birth, and UC-processing can be initiated up to 48 h after collection without impacting on hUC-MSC characteristics. The removal of blood vessels before explant cultures improved hUC-MSC purity. Expansion in Minimum essential medium α supplemented with human platelet lysate increased reproducibility of the expansion rate and MSC characteristics as compared with Dulbecco's Modified Eagle's Medium supplemented with fetal bovine serum. The isolated hUC-MSCs showed a purity of ∼98.9%, a viability of >97% and a high proliferative capacity. Trilineage differentiation capacity of hUC-MSCs was reduced as compared with bone marrow-derived MSCs. Functional assays indicated that the hUC-MSCs were able to inhibit T-cell proliferation demonstrating their immune-modulatory capacity.

CONCLUSIONS

We present a robust and standardized method to isolate and expand hUC-MSCs, minimizing technical variability and thereby lay a foundation to advance reliability and comparability of results obtained from different donors and different studies.

Fetal growth restriction inhibits childhood growth despite catch-up in discordant identical twins: an observational cohort study

OBJECTIVE

Research suggests that postnatal catch-up growth after fetal growth restriction (FGR) occurs frequently. Yet, postnatal growth in singletons may be influenced by multiple factors. Identical twins with discordant prenatal growth, termed selective FGR (sFGR), can be regarded as a natural experiment eliminating these sources of bias.

DESIGN

Observational cohort study.

METHODS

Monochorionic twins with sFGR born between 2002 and 2017 (aged 3-17 years) were eligible. Growth measurements (height, weight, head circumference, and body mass index) were performed at follow-up. Detailed growth curves documented by a systematic primary care system in the Netherlands were collected. Measurements were converted to standard deviation scores (SDSs). A mixed-effects model was used to assess within-pair SDS difference and individual height SDS relative to target height SDS.

RESULTS

Forty-seven twin pairs (94 children) were included at a median age of 11 (interquartile range 8-13) years. At the last measurement, smaller twins at birth had a lower height SDS [-0.6 vs -0.3, P < .001, median difference 0.5 (95%CI 0.4-0.7)], lower weight SDS [-0.5 vs -0.1, P < .001, median difference 0.8 (95%CI 0.5-1.0)], and lower head circumference SDS [-0.5 vs 0.2, P < .001, median difference 0.8 (95%CI 0.6-0.9)] compared to larger twins. These differences persisted until the age of 17. Smaller twins showed rapid catch-up growth in the first 2 years and reached their target height range between 8 and 11 years.

CONCLUSIONS

Identical twins with discordant prenatal growth maintain a modest but significant difference in height, weight, and head circumference, indicating a persistent, inhibitory effect of an adverse intrauterine environment on childhood growth.

Increased Risk of Retinopathy of Prematurity in Donors with Twin-to-Twin Transfusion Syndrome: A Cohort Study

INTRODUCTION

The purpose of this study was to evaluate the within-pair difference in retinopathy of prematurity (ROP) between donors and recipients with twin-to-twin transfusion syndrome (TTTS) and to identify risk factors for ROP development.

METHODS

This retrospective cohort study included 147 TTTS twin pairs managed between 2002 and 2022 and eligible for ROP screening. Primary outcomes were any stage ROP and severe ROP. Secondary outcomes were hemoglobin at birth, red blood cell transfusions, mechanical ventilation days, postnatal steroids, and neonatal morbidity. Donor status was defined as having polyhydramnios pre-laser.

RESULTS

Rates of any stage ROP (23% vs. 14%) and severe ROP (8% vs. 3%) were significantly higher in donors compared to recipients. Donors received a higher number of blood transfusions (1 [±1.9] versus 0.7 [±1.5]). Five factors were univariately associated with any stage ROP: donor status (odds ratio [OR] 1.9; 95% CI 1.3-2.9), lower gestational age (GA) at birth (OR 1.7; 95% CI 1.4-2.1), small for GA (OR 2.1; 95% CI 1.3-3.5), mechanical ventilation days (OR 1.1; 95% CI 1.1-1.2), and blood transfusions in phase 1 (OR 2.3; 95% CI 1.2-4.3). Three factors were independently associated with any stage ROP: donor status (OR 1.8; 95% CI 1.1-2.9), lower GA at birth (OR 1.6; 95% CI 1.2-2.1), and mechanical ventilation days (OR 1.1, 95% CI 1.0-1.1). Donor status was univariately associated with severe ROP (OR 2.3, 95% CI 1.1-5.0).

CONCLUSION

Any stage ROP and severe ROP are detected twice as frequently in donors compared to recipients. Increased awareness for ROP is needed in donors, especially those with lower GA at birth and longer duration of mechanical ventilation.

Insecure attachment and internalizing behavior problems in growth discordant identical twins

BACKGROUND

Psychosocial development in monochorionic (MC) twins born after selective fetal growth restriction (sFGR) has been unreported to date, despite its importance for daily functioning and future relationships.

AIMS

To investigate psychosocial development, attachment and school functioning in MC twins with sFGR and compare outcomes with the general population and between smaller and larger twins.

STUDY DESIGN

Observational cohort study.

SUBJECTS

MC twins with sFGR (defined as a birth weight discordance ≥20 %) born between 2002 and 2017 and aged 3-17 years.

OUTCOME MEASURES

Multiple parent report questionnaires: the Child Behavior Checklist (social-emotional development and behavior), the (Early) Childhood Behavior Questionnaire Very Short Form (temperament), the Attachment Insecurity Screening Inventory (attachment) and a school functioning questionnaire.

RESULTS

Median age for the 48 twin pairs was 11 (interquartile range (IQR) 8-13) years. Attachment insecurity for both twins was higher than in the general population for ambivalence/resistance (34 % (21/62) vs. 16 %, p = 0.024) and total attachment insecurity (35 % (22/62) vs. 16 %, p = 0.016). Smaller twins had more internalizing behavioral problems, i.e. negative emotions and behaviors turned inwards (22 % (10/46) vs. 11 % (5/46), p = 0.021) and a higher negative affect, i.e. more likely to experience negative emotions (3.2 (2.9-3.7) vs. 2.9 (2.2-3.2), p = 0.009) than larger twins, as well as a lower secondary school level (p = 0.031).

CONCLUSION

MC twins with sFGR have more ambivalent/resistant attachment insecurity following the complicated pregnancy course. Smaller twins have a tendency towards negative emotions and internalizing behaviors compared to larger twins, indicating an increased sensitivity for depression and anxiety.

Impact of placental sharing and large bidirectional anastomoses on birthweight discordance in monochorionic twins: a retrospective cohort study in 449 cases

BACKGROUND

In monochorionic twin pregnancies, the fetuses share a single placenta. When this placenta is unequally shared, a discordant antenatal growth pattern ensues resulting in high rates of perinatal morbidity and mortality. Understanding placental pathophysiology is paramount in devising feasible antenatal management strategies. Unequal placental sharing is not the sole determinant of birthweight discordance as there is no one-to-one relationship with placental share discordance. Placental angioarchitecture, especially the presence of large bidirectional anastomoses, is thought to affect this relationship by allowing for a compensatory intertwin blood flow.

OBJECTIVE

This study aimed to assess whether placental angioarchitecture can affect birthweight discordance in live-born monochorionic twins, the aim of our study was 2-fold: (1) to assess the relationship between birthweight discordance and placental share discordance and (2) to examine to what extent large bidirectional anastomoses can compensate for the effect of unequal placental sharing on birthweight discordance, with a subgroup analysis for umbilical artery Doppler flow patterns in cases with a birthweight discordance of ≥20%.

STUDY DESIGN

This was a retrospective cohort study that included monochorionic twin pregnancies observed in our center between March 2002 and June 2021, in which twins with a birthweight discordance of ≥20% were classified according to umbilical artery Doppler flow patterns of the smaller twin. We excluded cases with twin-twin transfusion syndrome and twin anemia polycythemia sequence. Monochorionic placentas of live-born twins were injected with dye, and images were saved for computer measurements of placental sharing and the diameter of anastomoses. Univariate linear regressions of the relationship between placental share discordance and birthweight discordance (both calculated as larger weight or share-smaller weight or share/larger weight or share×100%) and the relationship between arterioarterial and venovenous diameters and birthweight ratio/placental territory ratio were performed.

RESULTS

A total of 449 placentas were included in the analysis. Placental share discordance was positively correlated with birthweight discordance (β coefficient, 0.325; 95% confidence interval, 0.254-0.397; P<.0001). The arterioarterial diameter was negatively correlated with birthweight ratio/placental territory ratio (β coefficient, -0.041; 95% confidence interval, -0.059 to -0.023; P<.0001), meaning that an increase in arterioarterial diameter leads to less birthweight discordance than expected for the amount of placental share discordance. There was no relationship between venovenous diameter and birthweight ratio/placental territory ratio (β coefficient, -0.007; 95% confidence interval, -0.027 to 0.012; P=.473).

CONCLUSION

Birthweight discordance in monochorionic twins was strongly associated with placental share discordance. Large arterioarterial anastomoses can mitigate the effect of unequal placental sharing.

Gestational Age at Birth and outcome in Monochorionic Twins with Different Types of Selective Fetal Growth Restriction: A Systematic Literature Review

This systematic review aims to assess the gestational age at birth and perinatal outcome (intrauterine demise (IUD), neonatal mortality and severe cerebral injury) in monochorionic (MC) twins with selective fetal growth restriction (sFGR), according to Gratacós classification based on umbilical artery Doppler flow patterns in the smaller twin. Seventeen articles were included. Gestational age at birth varied from 33.0-36.0 weeks in type I, 27.6-32.4 weeks in type II, and 28.3-33.8 weeks in type III. IUD rate differed from 0-4% in type I to 0-40% in type II and 0-23% in type III. Neonatal mortality rate was between 0-10% in type I, 0-38% in type II, and 0-17% in type III. Cerebral injury was present in 0-2% of type I, 2-30% of type II and 0-33% of type III cases. The timing of delivery in sFGR varied substantially among studies, particularly in type II and III. The quality of evidence was moderate due to heterogenous study populations with varying definitions of sFGR and perinatal outcome parameters, as well as a lack of consensus on the use of the Gratacós classification, leading to substantial incomparability. Our review identifies the urgent need for uniform antenatal diagnostic criteria and definitions of outcome parameters. This article is protected by copyright. All rights reserved.

Respiratory distress syndrome and bronchopulmonary dysplasia after fetal growth restriction: Lessons from a natural experiment in identical twins

BACKGROUND

Fetal growth restriction (FGR) is thought to negatively affect lung development resulting in increased respiratory morbidity. However, research performed in singletons is often limited by a certain level of bias caused by individual differences in genetic constitution, obstetrical and maternal factors.

METHODS

Respiratory morbidity was compared between the smaller and the larger twin in monochorionic twins with selective fetal growth restriction (sFGR), defined as a birth weight discordance ≥ 20%, born in our center between 2010 and 2019 in this retrospective study. Respiratory distress syndrome (RDS) was diagnosed based on the clinical picture of a neonate with respiratory failure requiring mechanical ventilation and/or surfactant, confirmed by a chest X-ray. Bronchopulmonary dysplasia (BPD) was diagnosed when the neonate required treatment with >21% oxygen for at least 28 days.

FINDINGS

Median gestational age at birth for the 94 included pregnancies was 32.4 (IQR 30.4-34.3) weeks. Within-pair analyses showed that the prevalence of RDS was lower in the smaller twin compared to the larger twin, 19.1% (18/94) vs 34.0% (32/94), respectively (p = 0.004). The odds of RDS for the larger twin was doubled (OR 2.1 (CI95% 1.3-3.5). In contrast, the rate of BPD in the smaller twin was higher as opposed to the larger twin, 16.7% (15/90) vs 6.7% (6/89), respectively (p = 0.008), with a more than doubled odds (OR 2.5 (CI95% 1.3-4.9)).

INTERPRETATION

Despite being genetically identical, sFGR twins have different respiratory outcomes. Adverse growth condition in utero in the smaller twin is associated with a reduced odds of RDS at birth but a more than doubled odds of BPD, reflecting the pathophysiologic adverse effect of growth restriction on lung development.

FUNDING

The Dutch Heart Foundation (2017T075).

Twin-Twin Transfusion Syndrome with Anemia-Polycythemia: Prevalence, Characteristics, and Outcome

The aim of this study was to estimate the prevalence of co-existing anemia-polycythemia (AP) in twin pregnancies with twin-twin transfusion syndrome (TTTS) prior to laser surgery, and to evaluate the characteristics and outcomes in TTTS twins with and without AP. All TTTS cases treated with laser between 2001 and 2019 were retrospectively reviewed for the presence of AP before surgery. AP was defined as delta middle cerebral artery–peak systolic velocity > 0.5 multiples of the median. The primary outcome was a composite of perinatal survival and severe neurodevelopmental impairment (NDI). Secondary outcomes included procedure-related characteristics, severe neonatal morbidity, and disease-free survival. In total, 66% (461/696) of TTTS twin pregnancies were eligible for analysis. AP was detected in 15% (70/461) of the TTTS twins prior to laser surgery. Gestational age at laser was higher in the TTTS+AP group compared to the TTTS-only group—21.0 weeks (interquartile rage (IQR): 18.8–24.0) versus 19.3 weeks (IQR: 17.3–21.9), respectively (p < 0.0001). Fewer placental anastomoses were detected in the TTTS+AP group than in the TTTS-only group—five (IQR: 4–6) versus six (IQR: 5–8), respectively (p < 0.0001). Perinatal survival was 77% (599/782) in the TTTS-only group and 83% (118/142) in the TTTS+AP group (p = 0.130). Severe NDI was 8% (28/370) in TTTS-only and 3% (2/74) in TTTS+AP. TTTS-only twins showed more severe neonatal morbidity than twins with TTTS+AP—23% (132/575) versus 11% (13/115), respectively (p = 0.005). Disease-free survival was lower in the TTTS-only group compared to the TTTS+AP group—62% (341/548) versus 73% (72/98), respectively (p = 0.046). Thus, AP complicates 15% of TTTS twins prior to laser. TTTS+AP twins show a different placental angioarchitecture, a later time of onset of the disease, and a more favorable outcome.

Twin-Twin Transfusion Syndrome with and without Selective Fetal Growth Restriction Prior to Fetoscopic Laser Surgery: Short and Long-Term Outcome

As twin-twin transfusion syndrome (TTTS) and selective fetal growth restriction (sFGR) are both prevalent complications of monochorionic (MC) twin pregnancies, its coexistence is not uncommon. The aim of this study is to evaluate the short and long-term outcome in TTTS with and without sFGR prior to fetoscopic laser coagulation. All TTTS cases treated with laser surgery at our center between 2001–2019 were retrospectively reviewed for the presence of sFGR, defined as an estimated fetal weight (EFW) <10th centile. We compared two groups: TTTS-only and TTTS + sFGR. Primary outcomes were perinatal survival and long-term severe neurodevelopmental impairment (NDI). Of the 527 pregnancies eligible for analysis, 40.8% (n = 215) were categorized as TTTS-only and 59.2% (n = 312) as TTTS + sFGR. Quintero stage at presentation was higher in the TTTS + sFGR group compared to the TTTS-only group (57% compared to 44% stage III). Separate analysis of donors showed significantly lower perinatal survival for donors in the TTTS + sFGR group (72% (224/311) compared to 81% (173/215), p = 0.027). Severe NDI at follow-up in long-term survivors in the TTTS-only and TTTS + sFGR group was present in 7% (13/198) and 9% (27/299), respectively (p = 0.385). Both sFGR (OR 1.5;95% CI 1.1–2.0, p = 0.013) and lower gestational age at laser (OR 1.1;95% CI 1.0–1.1, p = 0.001) were independently associated with decreased perinatal survival. Thus, sFGR prior to laser surgery is associated with a more severe initial presentation and decreased donor perinatal survival. The long-term outcome was not affected.

Placental characteristics in monochorionic twins with selective intrauterine growth restriction in relation to the umbilical artery Doppler classification

INTRODUCTION

The objective of this study was to evaluate the placental characteristics of monochorionic twin pregnancies with selective intrauterine growth restriction (sIUGR) classified according to the Gratacós classification based on umbilical artery Doppler measurements.

METHODS

All consecutive placentas from monochorionic twin pregnancies with sIUGR, (defined as a birthweight discordance > 25% and/or an estimated fetal weight in one twin <10th centile) examined between May 2002 and February 2018 were included in the study. Each placenta was injected with colored dye to study the angioarchitecture. Primary outcomes were placental share discordance and diameter of the arterio-arterial anastomoses in relation to the umbilical artery Doppler types of sIUGR (Gratacós classification).

RESULTS

Of the 83 sIUGR twins included, 27 were classified as Gratacós type I, 24 as type II and 32 as type III. The median gestational age at delivery was 34.3 weeks for type I, compared to 31.2 weeks and 31.6 weeks for type II and type III respectively. A trend towards a higher placental share discordance in type III sIUGR was observed. The median arterio-arterial diameter was 1.7 mm (0.8-2.6) in type I, 1.7 mm (1.2-2.2) in type II and 2.8 (2.0-3.5) mm in type III (p < 0.01).

DISCUSSION

Type III sIUGR placentas appear to be characterized by a larger diameter of the arterio-arterial anastomoses and a larger placental share discordance compared to type I and II sIUGR. The insights in the placental architecture of sIUGR placentas may offer new views on the pathophysiology of the disease.