The individual fetal weight/estimated placental weight ratios in monochorionic twins with selective intrauterine growth restriction

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.

Effect of Hypoxia on Glucose Transporter 1 and 3 Gene Expression in Placental Mesenchymal Stem Cells Derived from Growth-Restricted Fetuses

(1) Background: Glucose is transferred from maternal blood to the fetus by glucose transporters. What is the effect of hypoxia on the gene expression of placenta glucose transporter 1 (GLUT1) and glucose transporter 3 (GLUT3) in growth-restricted fetus is interesting. (2) Methods: The gene expression of GLUT1 and GLUT3 and the protein expression of HIF-1α were evaluated under nonhypoxic conditions and after 4 and 8 h under hypoxic conditions in placental mesenchymal stem cells derived from monochorionic twin pregnancies with selective intrauterine growth restriction. (3) Results: The gene expressions of GLUT1 and GLUT3 under hypoxia conditions were higher in placental mesenchymal stem cells derived from appropriate-for-gestational-age fetuses than in those from selective intrauterine growth-restricted fetuses. However, the protein expression of hypoxia induced factor-1 α (HIF-1α) at hypoxia condition was not lower in placenta mesenchymal stem cells from selective intrauterine growth-restricted fetuses than in placental mesenchymal stem cells from appropriate-for-gestational-age fetuses. (4) Conclusions: Hypoxia-induced upregulation of GLUT1 and GLUT3 expression was decreased in placental mesenchymal stem cells from selective intrauterine growth-restricted fetuses but not due to decreased HIF-1α expression. Selective growth-restricted fetuses have less capacity for hypoxia-induced upregulation of placental glucose transport.

Association between Respiratory Distress Syndrome of Newborns and Fetal Growth Restriction Evaluated Using a Dichorionic Twin Pregnancy Model

AIMS

To evaluate the association between respiratory distress syndrome (RDS) and intrauterine fetal growth restriction (IUGR) by using a dichorionic twin model.

METHODS

We retrospectively analyzed twins delivered between September 2012 and December 2018. A dichorionic (DC) twin pregnancy with selective IUGR (sIUGR) was defined as the presence of (i) a birthweight discordance of ≥25% and (ii) a smaller twin with birth weight below the 10th percentile. Pregnancies with major fetal anomalies, delivery at gestational age below 23 weeks, and intrauterine fetal demise were excluded.

RESULTS

We included 53 DC twins with sIUGR. The sIUGR twin had a higher risk of RDS than did his appropriate for gestational age (AGA) cotwin (32.1% vs. 11.3%, p = 0.001); however, the risk of severe RDS did not significantly differ between the twins (17.0% vs 9.4%, p = 0.125). The findings of logistic regression analysis indicated that younger gestational age (weeks) at delivery (odds ratio = 0.48, p < 0.001) and IUGR (odds ratio = 13.87, p = 0.009) were significant risk factors for RDS in newborns in DC twin pregnancies with selective sIUGR.

CONCLUSIONS

IUGR was identified as a risk factor for newborn RDS. However, the association between IUGR and severe newborn RDS was not significant possibly due to the small sample size of this study.

The relationship between placental characteristics and birthweight discordance in different types of selective intrauterine growth restriction in monochorionic diamniotic twins: A single-center 7 year cohort study

OBJECTIVE

To clarify the relationships between placental characteristics and birthweight discordance in three types of selective intrauterine growth restriction (sIUGR) in monochorionic diamniotic twins.

METHODS

A retrospective cohort study was conducted between april 2013 and april 2020. Associations between placental characteristics and birthweight discordance were evaluated through multiple linear regression analyses with two models for each sIUGR type. Model A was adjusted for gestational age, Model B additionally adjusted for the impact of placental characteristics interacted.

RESULTS

In cases of type I sIUGR, birthweight discordance ratio was positively associated with placental territory discordance ratio [(β = 0.181,95%CI(0.072,0.290), p < 0.05), (β = 0.239,95%CI(0.125, 0.353), p < 0.05)] under both Model A and Model B. In-type II sIUGR [(β = -0.012,95%CI(-0.020, -0.004), p < 0.05) (β = -0.010,95%CI (-0.018, -0.002), p < 0.05)] and type III sIUGR [(β = -0.011,95%CI (-0.021, -0.001), p < 0.05), (β = -0.012,95%CI(-0.022, -0.003), p < 0.05)], birthweight discordance ratio was negatively associated with the total diameter of all the anastomoses as calculated with both Model A and Model B.

CONCLUSION

Birthweight discordance is primarily related to placental territory discordance in type I sIUGR, whereas vascular anastomoses play important roles for growth-restricted fetal compensation in type II and III sIUGR.

Placental characteristics in different types of selective fetal growth restriction in monochorionic diamniotic twins

INTRODUCTION

This study aimed to explore the differences in placental characteristics among three types of selective fetal growth restriction (sFGR) in monochorionic diamniotic twin pregnancies.

MATERIAL AND METHODS

A total of 123 placentas with sFGR between April 2013 and October 2019 were retrospectively analyzed after dye injection. Placental characteristics were compared among the three types.

RESULTS

The gestational age at diagnosis and delivery was less in sFGR II and III than in sFGR I (22.9 [21.7-33.6], 23.3 [20.0-26.1] and 25.7 [19.0-35.0] weeks, p < 0.001; 32.3 [31.6-35.1], 34.1 [29.9-34.7] and 35.5 [34.0-37.0] weeks, p < 0.001). The birthweight discordance ratio was less in sFGR I than in sFGR II (0.28 [0.14-0.43] and 0.30 [0.23-0.37], p < 0.001). The prevalence of a thick artery-artery anastomosis was higher in sFGR III than in sFGR I or II (81.8%, 44.9% and 48.6%, p = 0.010). The placental territory discordance ratio was higher in sFGR II and III than in sFGR I (0.60 [0.17-0.88], 0.60 [0.01-0.80] and 0.50 [0.01-0.71], p = 0.001).

CONCLUSIONS

Compared with sFGR I, the earlier onset time of sFGR II and III might be due to their higher placental territory discordance. The prevalence of thick artery-artery anastomoses was expected to be higher in sFGR III than in sFGR I or II.

Characteristics of vascular anastomoses in monochorionic twin 587 placentas with selective intrauterine growth restriction via 89 three-dimensional computed tomography angiography

OBJECTIVE

To determine the characteristics of the choriovascular anatomy, especially the potential role of arteriovenous perfusion imbalance in the pathogenesis of selective intrauterine growth restriction (sIUGR) using three-dimensional computed tomography angiography (3D-CTA).

METHOD

Computed tomography angiography of the placental choriovascular tree from 15 twins with sIUGR and 15 twins without sIUGR were analyzed, and inter-twin vascular anastomoses were compared between the placentas from these two groups. The parameters evaluated were the presence and measures of artery-to-artery anastomoses (AAA), vein-to-vein anastomoses (VVA) or artery-to-vein anastomoses (AVA).

RESULTS

The frequency of AAA, VVA, and AVA did not differ significantly between sIUGR and without sIUGR-pairs. The area of the vein draining to the AVA in the larger twin's placenta was significantly greater in sIUGR compared to when no sIUGR was present. Based on the net cross-sectional area difference we speculate that in sIUGR there is net flow from the smaller to the larger twin.

CONCLUSION

We used 3D-CTA to display the vascular anastomoses in sIUGR twin pairs, demonstrating a difference in cross-sectional diameter of the vein draining to the AVA.

Mode of conception does not affect fetal or placental growth parameters or ratios in early gestation or at delivery

PURPOSE

Ratio of fetal weight to placenta size varies by mode of conception (fertility treatments utilized) in animals. Our objective was to assess whether fertility treatments also affect these ratios in humans.

METHODS

In this retrospective study, we assessed two cohorts: (a) early gestation cohort, women with singleton pregnancies who underwent first trimester vaginal ultrasound and (b) delivered cohort, women who delivered a live-born, singleton infant with placenta disposition to pathology. Crown rump length (CRL) and estimated placental volume (EPV) were calculated from first trimester ultrasound images using a validated computation. Infant birth weight (BW), pregnancy data, placental weight (PW), and placental histopathology were collected. Fetal growth-to-placental weight ratios (CRL/EPV; BW/PW) and placentas were compared by mode of conception. Linear regression was used to adjust for confounding variables.

RESULTS

Two thousand one hundred seventy patients were included in the early gestation cohort and 1443 in the delivered cohort. Of the early gestation cohort (a), 85.4% were spontaneous conceptions, 5.9% Non-IVF Fertility (NIFT), and 8.7% IVF. In the delivered cohort (b), 92.4% were spontaneous, 2.1% NIFT, and 80 5.5% IVF. There were no significant differences between fetal growth-to-placental weight parameters, ratios, and neonatal birth measurements based on mode of conception. Placenta accreta was significantly higher in the patients receiving fertility treatments (1.2 versus 3.6%, p < 0.05).

CONCLUSIONS

Mode of conception does not appear to influence fetal growth-to-placental weight ratios throughout gestation. In addition, findings in animal models may not always translate into human studies of infertility treatment outcomes.

Effects of inter-twin vascular anastomoses of monochorionic twins with selective intrauterine growth restriction on the contents of placental mitochondria DNA

Background

Placental mitochondrial DNA (mtDNA) has been proposed to be an indicator for placental hypoxia. This study was designed to evaluate the effect of vascular anastomoses between monochorionic (MC) twins on placental mtDNA.

Methods

In this study, twin-twin transfusion syndrome (TTTS) treated with laser therapy and MC twins without TTTS (without laser therapy) resulting in two live babies were included in this study. The placental mtDNA fold changes (FC) between the small and large twins were analyzed using real-time quantitative PCR. TTTS twins with selective intrauterine growth restriction (sIUGR) are categorized as group 1, TTTS without sIUGR as group 2, MC twins without TTTS but with sIUGR as group 3, and MC twins without both TTTS and sIUGR as group 4.

Results

There were seven cases in group 1, eight in group 2, 26 in group 3, and 24 in group 4 cases. The placental mtDNA FC were significantly higher in group 1 (1.57 ± 0.9) compared to that of the group 3 (0.86 ± 0.6).

Conclusion

In MC twin pregnancies with sIUGR, the placental mtDNA FC between the small and large twins are different between cases with and without inter-twin anastomoses. These findings suggest that the inter-twin anastomoses in the MC twins with sIUGR may provide rescue perfusion from the appropriate-for-gestational-age twin to the sIUGR one.

Electronic supplementary material

The online version of this article (10.1186/s12884-018-1702-8) contains supplementary material, which is available to authorized users.

Preliminary report of altered insulin secretion pattern in monochorionic twin pregnancies complicated with selective intrauterine growth restriction

OBJECTIVE

Fetuses with intrauterine growth restriction (IUGR) have adaptive hormonal changes including changes in insulin, which may increase their future risks for developing diabetes mellitus. This study compared cord blood insulin concentrations in IUGR and appropriate for gestational age (AGA) fetuses in a monochorionic (MC) twin model.

MATERIALS AND METHODS

Ten pairs were classified as selective IUGR (sIUGR) based on having one twin weight below the 10th percentile and with an intertwin birth weight discordance>20%. Fourteen pairs without IUGR were included as a comparison group. Pregnancies with twin-twin transfusion syndrome, congenital structural malformations, and genetic abnormalities were excluded. Insulin and glucose concentrations were measured in cord venous blood at the time of delivery.

RESULTS

Cord blood insulin concentrations of sIUGR fetuses were significantly lower than those of AGA counterpart fetuses in MC twins affected by sIUGR (5.1±4.1 mU/L, range: 0.7-9.9 mU/L for sIUGR fetuses and 12.2±7.6 mU/L, range: 3.5-23.7 mU/L for AGA fetuses, p=0.019). No significant difference in insulin concentrations between larger and smaller fetuses in MC twins without IUGR was observed. Insulin concentration was inversely correlated with gestational age of delivery in all fetuses except in those with sIUGR. We did not find any difference in cord blood glucose concentrations between the two fetuses in both groups.

CONCLUSION

Our data show reduced insulin secretion and loss of the physiological decline in concentration over time as gestational age increases in fetuses with sIUGR compared to AGA counterparts.

Placental weight and birth weight to placental weight ratio in monochorionic and dichorionic growth-restricted and non-growth-restricted twins

OBJECTIVE:

The aim of the present study was to compare the placental weight and birth weight/placental weight ratio for intrauterine growth-restricted and non-intrauterine growth-restricted monochorionic and dichorionic twins.

METHODS:

This was a retrospective analysis of placentas from twin pregnancies. Placental weight and the birth weight/placental weight ratio were compared in intrauterine growth-restricted and non-intrauterine growth-restricted monochorionic and dichorionic twins. The association between cord insertion type and placental lesions in intrauterine growth-restricted and non-intrauterine growth-restricted monochorionic and dichorionic twins was also investigated.

RESULTS:

A total of 105 monochorionic (intrauterine growth restriction=40; non-intrauterine growth restriction=65) and 219 dichorionic (intrauterine growth restriction=57; non-intrauterine growth restriction=162) placentas were analyzed. A significantly lower placental weight was observed in intrauterine growth-restricted monochorionic (p=0.022) and dichorionic (p<0.001) twins compared to non-intrauterine growth-restricted twins. There was no difference in the birth weight/placental weight ratio between the intrauterine growth restriction and non-intrauterine growth restriction groups for either monochorionic (p=0.36) or dichorionic (p=0.68) twins. Placental weight and the birth weight/placental weight ratio were not associated with cord insertion type or with placental lesions.

CONCLUSION:

Low placental weight, and consequently reduced functional mass, appears to be involved in fetal growth restriction in monochorionic and dichorionic twins. The mechanism by which low placental weight influences the birth weight/placental weight ratio in intrauterine growth-restricted monochorionic and dichorionic twins needs to be determined in larger prospective studies.

Increased Fetal Plasma Erythropoietin in Monochorionic Twin Pregnancies With Selective Intrauterine Growth Restriction and Abnormal Umbilical Artery Doppler

Hypoxia is the primary stimulus for the production of erythropoietin (EPO) in both fetal and adult life. Here, we investigated fetal plasma EPO concentrations in monochorionic (MC) twin pregnancies with selective intrauterine growth restriction (sIUGR) and abnormal umbilical artery (UA) Doppler. We diagnosed sIUGR in presence of (1) birth-weight discordance >20% and (2) either twin with a birth weight <10th percentile. An abnormal UA Doppler was defined as a persistent absent-reverse end diastolic flow (AREDF). The intertwin EPO ratio was calculated as the plasma EPO level of the smaller (or small-for-gestational-age) twin divided by the EPO concentration of the larger (or appropriate-for-gestational-age (AGA)) twin. Thirty-two MC twin pairs were included. Of these, 17 pairs were normal twins (Group 1), seven pairs were twins with sIUGR without UA Doppler abnormalities (Group 2), and eight pairs were twins with sIUGR and UA Doppler abnormalities (Group 3). The highest EPO ratio was identified in Group 3 (p< .001) but no significant differences were observed between Groups 1 and 2. Fetal hemoglobin levels did not differ significantly in the three groups, and fetal EPO concentration did not correlate with gestational age at birth. We conclude that fetal plasma EPO concentrations are selectively increased in MC twin pregnancies with sIUGR and abnormal UA Doppler, possibly as a result of uncompensated hypoxia.

Decreased Total Placental Mass Found in Twin-Twin Transfusion Syndrome Gestations with Selective Growth Restriction

Introduction: We examined placental weight characteristics associated with donor selective intrauterine growth restriction (SIUGR) among patients with twin-twin transfusion syndrome (TTTS) who underwent laser surgery. Materials and Methods: Fresh placental specimens were studied. Pregnancies with higher-order multiples, fetal demise, or disrupted or nonsubmitted placental specimens were excluded. Placental characteristics prospectively collected included total placental weight, individual placental weight, and placental share. Data were compared between pregnancies with SIUGR (TTTS + SIUGR group) and those without SIUGR (TTTS-only group). Results: Of 369 consecutive patients who underwent laser surgery for TTTS, 155 (42%) met inclusion criteria: 91 with TTTS + SIUGR and 64 with TTTS-only. Compared to the TTTS-only group, patients in the TTTS + SIUGR group had a lower total placental weight (608 ± 163 vs. 687 ± 224 g, p = 0.012), with a lower donor individual placental weight (237 ± 91 vs. 291 ± 124 g, p = 0.002), but no apparent difference in the individual placental weight of recipient twins (371 ± 109 vs. 396 ± 133 g, p = 0.211). Donor placental share was smaller in those pregnancies affected by SIUGR (38.7 ± 9.6 vs. 42.3 ± 9.8%, p = 0.029). Discussion: TTTS patients with SIUGR had a lower total placental weight and a lower donor individual placental weight compared to those without SIUGR. These findings suggest that differences in donor individual placental weights for SIUGR gestations may not solely be related to differences in placental share.

Preeclampsia in twin pregnancies: association with selective intrauterine growth restriction

OBJECTIVE

To identify the association between preeclampsia (PE) and selective intrauterine growth restriction (sIUGR) in twin pregnancies.

METHODS

This was a retrospective cohort study of 1004 twin pregnancies from 2008 to 2014. We specifically compared the incidence, clinical characteristics and outcomes of PE between sIUGR and normal-growth twin pregnancies.

RESULTS

PE occurred more frequently in sIUGR pregnancies [29.0% (51/176)] than in normal-growth twin pregnancies [13.1% (99/756), p < 0.001, adjusted odds ratio 3.29]. Among sIUGR, the incidence of PE was significantly higher in dichorionic (DC) pregnancies (37.5%, 30/80) than in monochorionic (MC) pregnancies (21.9%, 21/96). The rates of onset at <32 weeks (p = 0.045) and of severe PE (p = 0.025) were higher in sIUGR pregnancies with PE. The systolic blood pressure was also higher in sIUGR pregnancies with PE (152.6 ± 11.8 mmHg) than in normal-growth pregnancies with PE (148.0 ± 8.2 mmHg) (p = 0.042). Additionally, more sIUGR pregnancies were delivered at 32-36 weeks (p = 0.001), and fewer were delivered at ≥36 weeks (p < 0.001). Moreover, the prevalence of severe neonatal asphyxia was higher in sIUGR pregnancies with PE than in normal-growth pregnancies with PE (8.8% versus 2.5%, p = 0.020).

CONCLUSIONS

sIUGR is associated with increased odds of developing severe PE in twin pregnancies, leading to poorer perinatal outcomes.

Mitochondrial activation in the growth-restricted fetus of monochorionic twins

OBJECTIVE

To study the regulatory mechanisms of selective intrauterine growth restriction (sIUGR) independent of confounding genetic factors, monochorionic (MC) twins are the ideal model, because they have identical genomic DNA. We hypothesize that the intrauterine growth restriction fetus has mitochondrial activation compared with its larger counterpart, and sought to demonstrate this using the MC twin model.

DESIGN

Fetal cord blood and amniotic fluid of MC twins were prospectively collected during delivery. Mitochondrial DNA of cord blood was measured using real-time quantitative polymerase chain reaction (PCR), and mitochondria in amniotic fluid mesenchymal stem cells (AFMSCs) were analyzed with MitoTracker staining.

SETTING

Tertiary referring center.

PATIENT(S)

Forty-three pairs of MC twins, including 24 pairs with sIUGR and 19 pairs without.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Mitochondrial DNA contents were measured and presented as fold difference between the small and large fetuses. After staining with MitoTracker, mitochondrial intensity in AFMSCs was analyzed with the Image J program.

RESULT(S)

The fold differences of the cord blood mitochondrial DNA content between the small and large twins were significantly higher in the MC twins with sIGUR (2.5 ± 1.2, n = 24 pairs) than in those without sIUGR (1.2 ± 0.3, n = 19 pairs). In addition, mitochondrial staining intensities were significantly higher in the AFMSCs derived from growth-restricted fetuses than from control fetuses.

CONCLUSION(S)

Mitochondrial activation in the sIUGR fetus of MC twins was likely regulated by locally adverse placental and blood flow conditions, instead of genetic factors.

Fetal growth and risk of childhood asthma and allergic disease

Introduction

Early genetic and environmental factors have been discussed as potential causes for the high prevalence of asthma and allergic disease in the western world, and knowledge on fetal growth and its consequence on future health and disease development is emerging.

Objective

This review article is an attempt to summarize research on fetal growth and risk of asthma and allergic disease. Current knowledge and novel findings will be reviewed and open research questions identified, to give basic scientists, immunologists and clinicians an overview of an emerging research field.

Methods

PubMed-search on pre-defined terms and cross-references.

Results

Several studies have shown a correlation between low birth weight and/or gestational age and asthma and high birth weight and/or gestational age and atopy. The exact mechanism is not yet clear but both environmental and genetic factors seem to contribute to fetal growth. Some of these factors are confounders that can be adjusted for, and twin studies have been very helpful in this context. Suggested mechanisms behind fetal growth are often linked to the feto-maternal circulation, including the development of placenta and umbilical cord. However, the causal link between fetal growth restriction and subsequent asthma and allergic disease remains unexplained. New research regarding the catch-up growth following growth restriction has posited an alternative theory that diseases later on in life result from rapid catch-up growth rather than intrauterine growth restriction per se. Several studies have found a correlation between a rapid weight gain after birth and development of asthma or wheezing in childhood.

Conclusion and clinical relevance

Asthma and allergic disease are multifactorial. Several mechanisms seem to influence their development. Additional studies are needed before we fully understand the causal links between fetal growth and development of asthma and allergic diseases.

The Relationships of Umbilical Venous Volume Flow, Birthweight and Placental Share in Monochorionic Twin Pregnancies With and Without Selective Intrauterine Growth Restriction

This study was conducted to investigate the relationship among umbilical venous volume flow, birthweight and placental share in monochorionic twins with or without selective growth restriction. Having excluded cases complicated with twin-to-twin transfusion syndrome and one co-twin suffering intrauterine fetal death, a total of 51 monochorionic twin pregnancies were divided into two groups as with (group 1) and without (group 2) selective intrauterine growth restriction. Umbilical venous volume flow was calculated by multiplying the umbilical vein cross-sectional area by half of the maximal velocity around mid-trimester. The placentas were cut along the vascular equator into two individual placental masses. The discordance of birthweight was calculated as [(birthweight of larger twin—birthweight of smaller twin)/birthweight of larger twin 100%]. The discordances of umbilical venous volume flow and placental share were calculated in a similar fashion. The median umbilical venous volume flow discordances (68.4% and 15.3% in groups 1 and 2 monochorionic twins, respectively) were similar and correlated well with the placental share discordances (66.6% and 18.5% in groups 1 and 2 monochorionic twins, respectively) but not with the birthweight discordance (28.6% and 6.4% in groups 1 and 2 monochorionic twins, respectively) in both groups. We concluded that the umbilical venous volume flow discordance reflects the placental share discordance rather than the birthweight discordance in monochorionic twin pregnancies.

Low Rate of Cerebral Injury in Monochorionic Twins With Selective Intrauterine Growth Restriction

This study was conducted to determine the incidence of cerebral injury as detected by postnatal brain scan in monochorionic twins with selective intrauterine growth restriction. Having excluded cases complicated with twin-to-twin transfusion syndrome and one co-twin suffering intrauterine fetal death, a total of 73 monochorionic twin pregnancies divided into absence (group I,n= 46) or presence (group II,n= 27) of selective intrauterine growth restriction. Mild cerebral injury was defined as presenting one of the following abnormal cranial scan findings: intraventricular hemorrhage grade I, grade II, lenticulostiate vasculopathy and/or subependymal pseudocysts, while severe cerebral injury was defined as presenting intraventricular hemorrhage grade III, grade IV, cystic periventricular leukomalacia (PVL) grade II or higher, porencephalic cysts, and/or ventricular dilatation. The incidence of mild cerebral injury was not significantly different between these two groups (eight cases in group I and six cases in group II). Except for one case that later developed a seizure, the majority (13 out of 14) of cases with minor brain scan anomalies were only transient, without significant clinical impact. There was only one case diagnosed with a major brain scan anomaly (periventricular leukomalacia) in group II. One severe brain injury and three neonatal deaths all belonged to group II with abnormal umbilical artery Doppler in the growth restricted twin. In conclusion, the incidence of severe cerebral injury in monochorionic twin pregnancies with selective intrauterine growth restriction was low, at 3.7%.