Academic literature on the topic 'Fetal weight discordance'

Introduction. Multifetal pregnancy is associated with an increased risk of perinatal morbidity and mortality. Type of placentation and discordant fetal growth may be risk factors of adverse pregnancy outcomes.Aim: to compare an impact of dichorionic and monochorionic twin pregnancies with symmetric and discordant fetal growth on perinatal outcomes, as well as morbidity and mortality.Materials and Methods. There was conducted a retrospective study of 485 pregnant women and paired 959 newborns. Depending on the type of chorionicity, subjects were stratified into two study groups being further subdivided into based on describing fetal weight discordance. The antenatal period and the neonatal outcome of newborns in groups and subgroups were compared.Results. We analyzed 308 dichorionic and 177 monochorionic twin pregnancies. It was found that neonate discordant growth was observed in 5.4 % and 13.4 % (p < 0.001), respectively. The incidence of assisted reproductive technologies was higher in dichorionic than in monochorionic twins comprising 66.5 and 40.7 % (р < 0.001). Antenatal mortality in monochorionic vs. dichorionic twins was by 8-fold higher. The preterm birth rate in monochorionic vs. dichorionic twins was 74.6 and 62.7% (p = 0.009), respectively. Neonate body weight in monochorionic vs. dichorionic twins was lowered comprising 1991 and 2430 gr. (р < 0.001), respectively. Low Apgar scores were more common for monochorionic twins with discordant body weight. The rate of early neonatal mortality in monochorionic vs. dichorionic twins was 4.4 % vs. 1.5 % (p = 0.009), whereas in dichorionic vs. monochorionic twins with weight discordance it was up to 5.8 and 10.5% (р < 0.001), respectively.Conclusion. Monochorionic twin pregnancy complicated with growth discordance is associated with a higher risk of adverse antenatal period as well as neonatal morbidity and mortality compared to symmetric DCDA twins. Chorionicity and growth discordancy represent important predictors for outcome of twin pregnancy.

Background: Monochorionic diamniotic (MCDA) twin pregnancies are associated with adverse perinatal outcome. Intertwin discordances at the time of nuchal translucency (NT) screening may have a value in the prediction of fetal loss or twin-to-twin transfusion syndrome. We aimed to determine the ability of intertwin NT and crown rump length (CRL) discordances among MCDA twins to predict adverse outcomes. Material and Methods: All MCDA twins with a documented routine ultrasound at 11 to 13+6 weeks’ gestation, and known pregnancy outcome between August 2003 and August 2012 were included. Receiver operating characteristic curves were used to determine the ideal NT and CRL discordances cut-off points that maximized the ability to predict adverse outcome, which was defined as any of: death of one or both twins, twin-to-twin transfusion syndrome, or estimated fetal weight or birth weight discordances ≥25%. Results: Of the 89 cases, 20 (22.5%) had at least one adverse outcome. NT discordance was more discriminatory of adverse outcome than was CRL discordance. The optimal values for predicting any adverse outcomes for NT were >23.7% and for CRL >3.5%. The positive predictive values for NT (52.4%) and CRL (29.8%) screening were relatively low; however, the lack of either NT or CRL discordances was more reassuring, with negative predictive values of 86.8% and 86.4%, respectively. Conclusions: NT discordance is more predictive for adverse fetal outcome in MCDA twins than CRL discordance. Neither NT nor CRL discordance are likely to modify the intensive monitoring required for these very high-risk pregnancies.

AbstractWe observed persistent first trimester growth disparity in a twin pregnancy following IVF-ET. The crown-rump length of the two fetuses was substantially different at 7 and 11 weeks and from the 20th week discordant growth was observed by intertwin differences in abdominal circumferences and estimated fetal weights. Birth weight discordance was 26.6% (1600/2180). This is apparently the first documentation of first trimester growth discordance persisting throughout pregnancy.

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

Significant management decisions in triplet pregnancies are made based mainly on ultrasound measurements of fetal growth, although there is a paucity of data examining the accuracy of fetal weight measurements in these gestations. To evaluate accuracy of prenatal ultrasound to diagnose growth abnormalities (intrauterine growth restriction, severe growth discordance) in triplet pregnancies, a retrospective cohort study of 78 triplet pregnancies (234 fetuses) delivered at a single tertiary hospital from January 2004 to May 2015 was performed. Growth percentiles from the last ultrasound were derived from estimated fetal weight using Hadlock's formula for each triplet. Growth discordance was calculated for each triplet set using the formula {(estimated fetal weight largest triplet - estimated fetal weight smallest)/estimated fetal weight largest}. These estimations were compared to birth weights. Sensitivity of ultrasound to predict ≥1 growth restricted fetus in a triplet set was 55.6% [95% CI 35.3, 74.5]; specificity was 100% [95% CI 93.0, 100]; positive predictive value (PPV) 100% [95% CI 74.7, 100]; negative predictive value (NPV) 81.0% [95% CI 73.2, 85.7%]. Sensitivity of ultrasound to detect fetal growth discordance >25% in a triplet set was 80.0% [95% CI 44.4, 97.5], specificity 94.1% [95% CI 85.6, 98.4]; PPV 66.7% [95% CI 42.4, 84.5]; NPV 97.0% [95% CI 90.2, 99.1]. Prenatal ultrasound currently remains the most reliable tool to screen for growth anomalies in triplet pregnancies; however, it appears to have less than ideal sensitivity, missing a number of cases of intra-uterine growth restriction and significant growth discordance.

OBJECTIVES: to evaluate the impact of laser therapy on inter-twin discordance in twin-to-twin transfusion syndrome (TTTS). METHODS: biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and estimated fetal weight were prospectively collected during a five-year period (1999 to 2004). The inter-twin discordance was expressed as a percentage of the largest twin's measurements. The measurements were made the day before laser, twice following laser and after delivery. The mean values of discordance in measurements and in fetal weight were calculated. ANOVA was used to compare mean values. RESULTS: the mean (SD) discordance for BPD, HC, AC, FL and estimated fetal weight the day before laser were 8.53% (5.28), 8.75% (2.76), 16.19% (4.85), 12.92% (5.13) and 28.50% (6.46) respectively. At the at 2nd ultrasound assessment after surgery were 4.37% (3.55), 3.73% (2.71), 8.90% (4.42), 6.61% (4.99) and 19.11% (8.01) respectively; and at birth the weight discordance was 18.55% (8.74). There was a significant decrease in discordance for HC and AC for each ultrasound assessment. CONCLUSIONS: there was a decrease in fetal growth discordance following laser therapy in TTTS. These changes might be related to re-adaptation of blood flow following laser therapy.

AbstractOur aim was to evaluate the ability of prenatal ultrasound scans to predict fetal growth discordance, and to examine the correlation between fetal weight estimated by ultrasound with actual birthweight in twin pregnancies. The study consisted of 221 twin pregnancies with ultrasound fetal weight estimates based on Hadlock's 4 parameter formula. Prediction of intertwin birthweight discordance was examined at 4 different intervals between ultrasound examination and delivery (0–7 days, n = 96; 8–14 days, n = 66; 15–21 days, n = 58; 22–28 days, n = 59 pregnancies), with a total of 279 ultrasound examinations. Birthweight discordance was considered as a difference of 20% or greater. The correlation between fetal weight estimated between 0 and 7 days and actual birthweight was calculated by intraclass correlation coefficient. The predictive values for intertwin discordance of 20% or more in the 0 to 7 days group were: sensitivity = 93.6%, specificity = 79.4%, positive predictive value = 89.2%, negative predictive value = 87.1% and accuracy = 88.6%. In the groups with scans carried out between 8 and 14 days, 15 and 21 days, and 22 and 28 days, the sensitivity and accuracy values were 95.8% and 84.9%, 95.6% and 84.5%, 90.9% and 84.8%, respectively. Fetal growth discordance in twins can be accurately predicted by ultrasound examination performed up to 28 days before birth. There is a good correlation between fetal weight estimated between 0 and 7 days and actual birthweight.

The relevance of the study lies in the significant increase in multiple pregnancies connected with the higher risk of perinatal complications, the controversy over the effects of chorionicity and sex of the babies on their birth weight, the need for timely diagnosis of fetal growth restriction, and associated morbidity. The objective of this study was to compare fetal weights at the birth of different variants of twins depending on chorionicity, gestational age, and sex. Materials and methods. During 2016-2020, 440 pairs of twins were examined: 375 dichorionic diamniotic and 65 monochorionic diamniotic (38 – boys, 27 – girls). Among dichorionic couples there were 186 (49.6%) opposite-sex, 98 (26.1%) same-sex males and 91 (24.3%) same-sex females. Fetal weight was measured at birth, and its relationship to chorionicity, fetal sex, a combination of same-sex or opposite-sex co-twins, and gestational age was assessed. Results. The average weight of 750 fetuses from dichorionic pairs (2570.0 ± 506.43 g) significantly exceeded the weight of 130 fetuses from monochorionic pairs (2333.4 ± 567.24 g, p < 0.0001). The same-sex male (2603.8 ± 532.29 g) and opposite-sex dichorionic diamniotic (2595.6 ± 490.17 g). twins’ masses significantly surpassed the mass of all other twins (p <0.05). In the group of dichorionic twins, the weight of boys exceeded the weight of girls (2638.1 ± 525.96 g vs. 2499.4 ± 475.84 g, p = 0.0002). This pattern was observed both inside the opposite-sex pairs (2674.2 ± 518.17 g vs. 2517.1 ± 448.24 g, p = 0.0019), and same-sex couples of boys compared to same-sex couples of girls (2603.8 ± 532.29 g and 2481.4 ± 503.08 g, respectively, p = 0.0224). No significant difference in the weight of girls of opposite-sex twins compared to same-sex couples was seen. In monochorionic pairs, the weight of male and female fetuses did not differ significantly. Birth weight discordance was found in all types of twins, the highest percentage of discordance was registered in monochorionic boys – 23.7%, second place in frequency took male dichorionic twins – 20.4%. Among the 30 discordant dichorionic opposite-sex twins in 19 (63.3%) cases, the male fetus was heavier. There was no significant difference in fetal weight when women were fertilized naturally and using assisted reproductive technologies. The average weight of children born by surrogate mothers exceeded the weight of children born by non-surrogate mothers (p = 0.0466). In the first pregnancy, children were born with a lower body weight compared to children born as a result of repeated pregnancies and in women who had a history of childbirth. Conclusion. The average weight of the fetuses of dichorionic twins was higher than the weight of the neonates f monochorionic pairs. The prevalence of the weight of boys over the weight of girls from dichorionic pairs and the absence of sex difference in fetal weight in monochorionic twins indicates the possibility of different functional activity of the placenta in fetuses of different sexes. Small for gestational age newborns were most often found in the group of female monochorionic twins and opposite-sex dichorionic pairs. Discordance of fetal mass was most common in monochorionic same-sex male twins. In discordant opposite-sex couples, the male fetus more often was heavier. There was no significant difference in newborn weight when women were fertilized naturally and with the use of assisted reproductive technologies. The average weight of surrogate-born children exceeded the weight of children born by non-surrogate mothers. In the first pregnancy, children were born with a lower body weight compared to children of multiparous and multigravida women.

Selective fetal growth restriction (sFGR) has been reported to occur in about 10–15% of monochorionic (MC) twins. The diagnosis of sFGR has been based on variable criteria including estimated fetal weight (EFW), abdominal circumference and/or the degree of fetal weight discordance. Recent studies tend to use a simple definition which includes the presence of an EFW less than the 10th percentile in the smaller twin. Some would argue that the intertwin fetal weight discordance should be included in the definition. Indeed this factor plays a major role in the complications presented by these cases. While the majority of cases with one fetus below the 10th percentile usually will also present with a large intertwin EFW discordance, the contrary is not always true. Thus, it is possible to find MC twins with remarkable intertwin EFW discordance but the EFW of both fetuses are still within normal ranges. Although it appears to be common sense that a large intertwin discrepancy might represent a higher risk for some of the complications described later in this review, there is no consistent evidence to support this notion. Therefore, due to its simplicity, a definition based on an EFW below 10th percentile in one twin is probably the most useful for clinical and research purposes.

This study was designed to evaluate the degree of placenta share discordance in relation to the betamethasone-induced return of positive end-diastolic flow in monochorionic twin pregnancies with selective intrauterine growth restriction (sIUGR) and abnormal umbilical artery Doppler. Monochorionic twins with sIUGR was defined as one twin having an estimated fetal weight below the 10th percentile combined with an estimated fetal weight discordance >25%. The umbilical artery Doppler directly prior to (D0) and 24 hours (D1) and 48 hours (D2) after the first dose of betamethasone administration was recorded. The estimated individual placental weight in monochorionic twins was obtained by cutting the placenta along the vascular equator into two territories; the placenta share discordance was calculated as [(estimated individual placental weight of appropriated for gestational age twin- estimated individual placental weight of growth restricted twin)/estimated individual placental weight of appropriated for gestational age twin] × 100%. Six (23.1%) of the 26 included cases achieved betamethasone-induced return of positive umbilical artery end-diastolic flow. The difference of placenta share discordance and birth weight discordance were not significantly different between twins with and without betamethasone-induced return of positive umbilical artery end-diastolic flow. Thus, according to our study results, it was proposed that although the placenta share discordance correlated with the abnormal umbilical artery Doppler in the IUGR fetus in monochorionic twin, the betamethasone-induced return of positive umbilical artery end-diastolic flow, however, did not reveal the similar relationship with the severity of placenta share discordance.

The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
Medicine, Faculty of
Population and Public Health (SPPH), School of
Graduate

OBJETIVOS: Comparar resultados perinatais entre gemelares, com dopplervelocimetria da artéria umbilical (AU) com fluxo diastólico presente (FDP), discordantes (GD) e concordantes (GC) em relação ao peso estimado fetal (PEF) e de acordo com a corionicidade. MÉTODOS: Estudo retrospectivo, caso-controle, desenvolvido na Clínica Obstétrica HCFMUSP entre janeiro 2005 e dezembro 2015. Para cada GD, foram selecionados 2 controles de GC, pareados pela idade gestacional do parto (IG) e corionicidade. Critérios de inclusão: discordância PEF >= 20%, Doppler da artéria umbilical (AU) com fluxo diastólico presente, ausência de malformação ou cromossomopatias, diamniótica, fetos vivos na primeira avaliação, ausência de complicações da monocorionicidade, parto na instituição. Resultados perinatais considerados: peso no nascimento, IG no parto, internação na unidade de terapia intensiva (UTI) neonatal, tempo de internação na UTI, suporte ventilatório (VM), hemorragia periventricular (HIPV), hipoglicemia (HG), icterícia (Ic), enterocolite necrosante (EN), sepse (Sp), óbito perinatal. Foram comparados os resultados perinatais dos fetos maiores e menores entre os grupos GD e GC. O resultado perinatal do feto menore foi comparado de acordo com a presença ou ausência de restrição de crescimento fetal (RCF). RESULTADOS: Selecionados 14 GD e 28 GC monocoriônicos (MC), e 38 GD e 76 GC dicoriônicos (DC). Fetos menores MC GD apresentaram maior TI (30,60 ± 20,19 vs 10,68 ± 11,64 dias, P<0,001), maior frequência de Ic (78,6% vs 28,6%; P=0,003; RC=9,17) e Sp (21,4% vs 0%; P=0,032; RC=23,42) em comparação com fetos menores GC. Nos DC, fetos menores GD apresentaram maior frequência de Sp (10,5% vs 1,3%; P=0,042; RC=8,82), HG (15,8% vs 3,9%; P=0,003; RC=4,56), EN (5,3% vs 0%; P=0,044; RC=20,63) e Ic (57,9% vs 28,9%, P=0,003; RC=3,38) comparado com fetos menores GC. Dentre os fetos menores MC, 10 (71,4%) tem RCF e dentre os DC menores, 21 (55,3%). Os gemelares menores sem RCF apresentaram frequência de morbidade neonatal similar entre os GD e GC, exceto pelo menor peso no nascimento do feto GD DC (2167,35 vs 2339,68g, P=0,026). CONCLUSÃO: Na presença do Doppler AU com FDP, o feto menor GD apresenta maior frequência de morbidades perinatais comparado aos fetos menores GC, independentemente da corionicidade. A presença da RCF, e não apenas a discordância de peso entre os fetos, parece ser responsável pela piora dos parâmetros de morbidade neonatal dentre os fetos GD
OBJECTIVE: The aim of this study was to compare the perinatal outcome between fetal weight discordance (FwD) with fetal weight concordant (FwC) twins, with umbilical artery (UA) Doppler with positive end-diastolic flow, according to chorionicity. METHODS: This was a retrospective case-control study of twin pregnancy over an 11-year period in a tertiary referral center. For each FwD, it was selected 2 controls of FwC matched for gestational age at delivery and chorionicity. The inclusion criteria were: estimated fetal weight (EFW) discordance >= 20%, UA Doppler with positive end-diastolic flow, absence of fetal malformation or chromosomal abnormalities, known chorionicity, diamniotic pregnancies, both fetuses alive at the first assessment, absence of monochorionic (MC) complications, delivery in our institution. The perinatal outcomes considered were: birth weigh (BW), length of hospital stay (LOS), admission to the neonatal intensive care unit (NICU), length of NICU stay, need for ventilator support, intraventricular hemorrhage (IVH), hypoglycemia (Hp), jaundice (JD), necrotizing enterocolitis (NE), sepsis (SP), intrauterine and neonatal death. Perinatal outcome of the smaller and larger twin comparisons between FwD with FwC were analyzed according to chorionicity. In addition, perinatal outcome from smaller twin was compared between FwD with FwC with and without fetal growth restriction (FGR). RESULTS: A total of 14 pregnancies with FwD and 28 with FwC of MC twin and 38 pregnancies with FwD and 76 with FwC of dichorionic (DC) twin were selected. According to chorionicity, in MC FwD group, the smaller twin presented presented longer LOS (30.60 ± 20.19 vs 10.68 ± 11.64 days, P < 0.001), higher frequency of SP (21.4% vs 0%; P=0.032; OR=23.42) and JD (78.6% vs 28.6%; P=0.003; OR=9.17) compared to smaller FwC twin; whereas in DC FwD group, smaller twin presented higher frequency of SP (10.5% vs 1.3%; P=0.042; OR=8.82), Hp (15.8% vs 3.9%; P=0.003; OR=4.56), NE (5.3% vs 0%; P=0.044; RC=20.63) and JD (57.9% vs 28.9%, P=0.003; OR=3.38) compared to smaller FwC twin. FGR in the smaller MC twin was observed in 71.4% (n=10) and in the smaller DC twin, 55.3% (n=21). Twin pregnancies without FGR had similar frequency of neonatal morbidity in discordant and concordant groups, excepted for the lower BW in FwD DC twins (2167.35 vs 2339.68g, P=0.026). CONCLUSION: Regardless chorionicity, perinatal morbidity is increased in the smaller discordant twin with UA Doppler with positive end-diastolic flow, compared to concordant smaller twin. Probably the FGR is responsible to complicate the perinatal outcome of smaller discordant twin

A gemelaridade apresenta algumas intercorrências específicas, como a discordância de peso entre fetos e recém-nascidos (RNs). O objetivo do presente estudo foi predizer a discordância de peso do exame ultra-sonográfico comparada à do parto e avaliar a morbidade e a mortalidade neonatais nas gestações gemelares discordantes quanto ao peso. Este foi um estudo retrospectivo, com levantamento dos casos do período de 1998 a 2004, no Setor de Gestações Múltiplas da Clínica Obstétrica do HCFMUSP. Na avaliação da predição ultra-sonográfica, foram inseridas 221 gestações gemelares e, na avaliação da morbidade e da mortalidade, 151 gestações com partos nessa instituição. A discordância de peso foi definida como >= 20%, sendo excluídos os casos de malformações fetais (n=43) e da Síndrome da transfusão feto-fetal (n=24). Para análise da adequação do peso ao nascimento, utilizou-se a curva de Alexander et al., 1998, para gêmeos. No estudo da predição, foram utilizados quatro intervalos de tempo em relação ao parto (0 a 7 dias - n = 96; 8 a 14 dias - n = 66; 15 a 21 dias - n = 58; 22 a 28 dias - n = 59 gestações), somando 279 avaliações. No grupo de 0 a 7 dias, a estimativa da sensibilidade foi de 93,6%, especificidade de 79,4%, valor preditivo positivo de 89,2%, valor preditivo negativo de 87,1% e acurácia de 88,6%. Nos demais grupos, a sensibilidade e a acurácia foram de 95,8% e 84,9%, 95,6% e 84,5%, 90,9% e 84,8%, respectivamente. Em relação à morbidade, 111 gestações eram concordantes (73,5%) e 40 discordantes quanto ao peso. No grupo discordante, 75% das gestações gemelares apresentaram pelo menos um recém-nascido com Restrição de Crescimento Fetal (RCF). Nesta análise, as gestações gemelares concordantes monocoriônicas obtiveram menor média de idade gestacional no parto (34,3 versus 36,2 semanas, p=0,004), menor peso médio (2067 versus 2334 gramas, p=0,0016) e maior tempo de internação (10,6 versus 7,3 dias, p=0,0023) que as gestações concordantes dicoriônicas. Nas gestações discordantes, não houve diferença significativa em relação à corionicidade. As gestações discordantes, com pelo menos um RN abaixo do percentil 10, apresentaram menor média de idade gestacional (35,2 versus 36,8 semanas, p=0,009) e maior tempo de internação (17,5 versus 8,2 dias, p=0,026). Não foi observada diferença significativa de morbidade e mortalidade entre RNs concordantes e discordantes, com pesos entre os percentis 10 e 90. Os fetos menores das gestações discordantes demonstraram maior freqüência de índice de Apgar inferior a 7 (27,5% versus 7,5%, p=0,01). A avaliação da mortalidade não demonstrou diferença significativa em relação aos grupos concordantes (3,7%) e discordantes (4,5%; p = 1,00). No presente estudo, conclui-se que os quatro grupos apresentaram adequada correlação entre a discordância de peso à ultra-sonografia e no nascimento, porém com melhor predição até sete dias antes do parto. A morbidade neonatal esteve relacionada à RCF do menor feto. A discordância de peso e a corionicidade não interferiram na mortalidade neonatal.
The aim of this study was to evaluate the ability of prenatal ultrasound scans to predict fetal growth discordance in twin pregnancies and perinatal morbidity/mortality associated with these cases. This was a retrospective study (1998-2004) involving twin pregnancies that were scanned and had their delivery at our Institution (HCFMUSP). Cases with fetal malformations (n=43) or twin to twin transfusion syndrome (n=24) were excluded. The study of ultrasound scans consisted of 221 twin pregnancies. The final morbidity/mortality study group consisted of 151 twin pregnancies. Birth weight was evaluated based on twin growth charts published by Alexander et al (1998) and weight discordance as a difference >= 20%. Small for gestacional age (SGA) was defined as birth weight below the 10th centile. The study of ultrasonographic prediction of interwin discordance was made using four different intervals between ultrasound examination and delivery (0 to 7 days, n = 96; 8 to 14 days, n = 66; 15 to 21 days, n = 58; 22 to 28 days, n = 59 pregnancies), with a total of 279 ultrasound examinations. In group 0 to 7 days, the sensitivity was 93,6%, specificity was 79,4%, positive predicted values was 89,2%, negative predicted values was 87,1% and accuracy was 88,6%. In the groups 8 to 14 days, 15 to 21 days and 22 to 28 days the sensitivity and accuracy were 95,8% and 84,9%, 95,6% and 84,5%, 90,9% and 84,8%, respectively. Birthweight discordance was observed in 40 sets of twins (26.5%) and 12 cases were monochorionic MC (30%). Twenty five cases (22.5%) in the non discordant group were MC. In the non discordant group, monochorionic pregnancies showed lower gestational age at delivery (34.3 versus 36.2 wks, p=0.004), lower mean birth weight (2067g versus 2334g, p=0.0016) and longer length of stay in hospital (10.6 versus 7.3 days, p=0.0023) compared to dichorionic twins. In the group with twin birthweight discordance, there were no significant differences between MC and DC pregnancies and 75% of the cases had at least one newborn with SGA. These cases were showed lower gestational age at delivery (35.2 versus 36.8wks, p=0.009) and longer length of stay in hospital (17.5 versus 8.2 days, p=0.026). In the discordant group, the smaller twin had a higher frequency of first minute Apgar score < 7 (27.5% versus 7.5%, p=0.01). Perinatal mortality rate was similar in both groups (discordant 4.5% and concordant 3.7%, p=1.0). There were no significant differences in morbidity and mortality between concordant and discordant twins when birth weight was between the 10 th and 90 th centile. In conclusion, there was a good correlation between fetal growth discordance predicted by prenatal scan and actual birth weight discordance. Neonatal morbidity was related to SGA. Excluding fetal malformation and TTTS cases, birth weight discordance in twin pregnancies is not a significantly associated with neonatal mortality.