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Outcomes of twin-twin transfusion syndrome managed by a specialised twin clinic.

INTRODUCTION: To determine the perinatal outcomes of monochorionic (MC) pregnancies complicated by the twin-twin transfusion syndrome (TTTS) that were managed in a specialised twin clinic at the KK Women's and Children's Hospital. METHODS: This was a 21-month retrospective study carried out from January 2002 to September 2003. MC pregnancies were followed up every two to three weeks with regular ultrasonographical and Doppler studies from the time monochorionicity was diagnosed. Standard criteria used for the diagnosis of TTTS are the presence of oligohydramnios/polyhydramnios sequence on ultrasonography. The severity of TTTS was staged according to Quintero's system. RESULTS: There were 77 sets of MC pregnancies in our database. 11 sets were diagnosed with TTTS, hence the incidence was 14.3 percent. The median gestation at diagnosis of TTTS was 17.4 (16.4 to 26) weeks. At first presentation, five were stage I, two were stage II, three were stage III and one was stage IV. Three pregnancies were terminated in the second trimester and one was lost to follow-up. Of the other seven, two were treated expectantly or delivered, four with amnioreduction/ septostomy and one with cord occlusion. The median gestation at delivery is 30.8 (26.7 to 36.9) weeks. Four (57 percent) were delivered before 32 weeks and these same four pairs required neonatal intensive care. The overall perinatal survival was 78 percent (11/14) and the median diagnosis to delivery interval was 10.7 (3.1 to 17.5) weeks. CONCLUSION: TTTS occurs in a significant proportion of MC pregnancies. The perinatal survival outcome of this group of patients managed in this clinic is comparable to that of other good centres.

Adult↗

Twin-twin transfusion syndrome in a dizygotic monochorionic-diamniotic twin pregnancy.

We present a case of twin-twin transfusion syndrome with discordant gender. Monochorionicity was confirmed by surgical pathology. Cytogenetic analysis showed normal 46,XX and 46,XY karyotypes. Microsatellite analysis using reliable pericentromeric markers was consistent with dispermic fertilization of two separate ova. This suggests that monochorionicity, rather than zygosity, may be responsible for the development of placental vascular anastomoses.

Abortion, Spontaneous↗

Estimating the extent of parameter bias in the classical twin design: a comparison of parameter estimates from extended twin-family and classical twin designs.

The classical twin design (CTD) circumvents parameter indeterminacy by assuming (1) negligible higher-order epistasis; and (2) either nonadditive genetic or common environmental effects are nonexistent, creating two potential sources of bias (Eaves et al., 1978; Grayson, 1989). Because the extended twin-family design (ETFD) uses many more unique covariance observations to estimate parameters, common environmental and nonadditive genetic parameters can be simultaneously estimated. The ETFD thereby corrects for what is likely to be the largest of the two sources of bias in CTD parameter estimates (Keller & Coventry, 2005). In the current paper, we assess the extent of this and other potential sources of bias in the CTD by comparing all published ETFD parameter estimates to CTD parameter estimates derived from the same data. CTD estimates of the common environment were lower than ETFD estimates of the common environment for some phenotypes, but for other phenotypes (e.g., stature in females and certain social attitudes), what appeared as the common environment was resolved to be assortative mating in the ETFD. On average, CTD estimates of nonadditive genetic factors were 43% lower, and additive genetic factors 63% higher, than ETFD estimates. However, broad-sense heritability estimates from the CTD were only 18% higher than ETFD estimates, highlighting that the CTD is useful for estimating broad-sense but not narrow-sense heritability. These results suggest that CTD estimates can be misleading when interpreted literally, but useful, albeit coarse, when interpreted properly.

Genetic Variation↗

Angioarchitecture of monochorionic placentas in relation to the twin-twin transfusion syndrome.

OBJECTIVE: Twin-twin transfusion syndrome in the midtrimester is associated with a perinatal mortality rate exceeding 80%. Although attributed to intertwin transfusion along vascular anastomoses, these occur in all monochorial placentas, not just the 10% with twin-twin transfusion syndrome. We compared fetoplacental angioarchitecture in monochorionic twin placentas with and without twin-twin transfusion syndrome. STUDY DESIGN: The fetoplacental circulations of both twins in 20 monochorial placentas were perfused immediately after delivery under optimal physiologic conditions and anastomoses delineated by dye-contrast injection. Ten were from pregnancies with evidence of midtrimester twin-twin transfusion syndrome and 10 were from pregnancies without twin-twin transfusion syndrome. RESULTS: Placentas from pregnancies with twin-twin transfusion syndrome had significantly fewer anastomoses than did those without twin-twin transfusion syndrome, both overall (median one versus six, respectively; p < 0.001) and for each of the different types (arterioarterial, venovenous, and arteriovenous, p < 0.001). Whereas multiple anastomoses were present in all controls, only one twin-twin transfusion syndrome placenta had more than a single communication. Anastomoses in the twin-twin transfusion syndrome group were more likely to be of the deep than the superficial type (80% vs 36% in controls, p < 0.01). CONCLUSIONS: Placental vascular anastomoses in monochorial pregnancies complicated by twin-twin transfusion syndrome are both fewer in number and of a different type than those without twin-twin transfusion syndrome. These differences seem implicated in the underlying pathophysiologic features of twin-twin transfusion syndrome and are of relevance to the development of newer therapies such as placental laser surgery.

Arterio-Arterial Fistula↗

Clinical evaluation of the risk of twin-to-twin transfusion syndrome using the relative power contribution of fetal heart rate fluctuations.

OBJECTIVES: In twin pregnancies, it has been suggested that fluctuations of the two fetal heart rates should be considered as two variates that affect each other. We therefore investigated whether the relative power contribution (RPC) of heart rate fluctuation between twins reflects the clinical severity of twin-to-twin transfusion syndrome. STUDY DESIGN: Sixty-three cases of twin pregnancy including 43 monochorionic twins and 20 dichorionic twins were studied. Thirteen monochorionic twins with polyhydramnios in one twin were regarded as twin-to-twin transfusion syndrome (TTTS). Of the 13 TTTS cases, 8 cases with polyhydramnios in one twin and oligohydramnios in the other were deemed to be a 'stuck' twin. The RPC of the very low frequency domain (VL; 0.0125-0.0625 Hz) of fetal heart rate fluctuation in the twin fetuses of monochorionic and dichorionic pregnancies was obtained within a week of delivery. The relationship between the value of the RPC and the outcome of these twins was examined. RESULTS: For both monochorionic and dichorionic twins the RPC of twin fetuses was significantly higher in TTTS twins than in twins without TTTS. In particular, in pregnancies that resulted in fetal death, early neonatal death, or hydrops of one of the twins, this twin had a higher RPC than the other twin. No significant difference was observed in the RPC value between twins of either monochorionic or dichorionic pregnancies that did not develop TTTS. Serial changes in RPC values were followed in 7 cases of TTTS. The RPC value rose rapidly just before delivery in three cases with resultant poor outcome. CONCLUSION: A rapid change in the RPC of twin fetuses measured using the VL frequency domain of fetal heart rate fluctuations may predict poor outcome in twin pregnancies.

Female↗

Deterioration in cord blood gas status during the second stage of labour is more rapid in the second twin than in the first twin.

OBJECTIVE: To compare in twin pregnancy the rate of deterioration in umbilical blood gas status during the second stage of labour, and to investigate whether the duration of the first twin's delivery has any effect on the blood gas status of the second twin. DESIGN: A retrospective study. SETTING: Department of Obstetrics and Gynaecology in a university teaching hospital. POPULATION: Twin pregnancies with both of the twins delivered by normal cephalic vaginal mode, at or beyond 34 weeks of gestation, over a period of seven years. Twins with any maternal or fetal complications including discordant growth, intrauterine growth restriction, intrauterine death, fetal malformations, fetal distress, pre-eclampsia and diabetes were excluded. METHODS: The first twins' second stage was defined as from the start of maternal pushing to his/her delivery, while the second twins' second stage started after the delivery of the first twin and ended by his/her delivery. The total duration of the second stage was the sum of the above two intervals. The correlations between the first twins' umbilical cord blood gas parameters and the duration of their own second stage, the second twins' umbilical cord blood gas parameters and the duration of their own second stage, as well as that of the total second stage, were studied. MAIN OUTCOME MEASURES: The changes of umbilical arterial pH of each twin with the duration of the corresponding second stage of labour, and the difference among them. RESULTS: A total of 51 cases were reviewed. The median gestation at delivery was 37 weeks. The median duration of first twins' second stage was 10 minutes (range 1-75) while that of the second twins' was 10 minutes (range 3-26). The first twins' second stage was inversely correlated with their arterial pH, venous pH and base excess [BE] (P < 0.01). Both the second twins' second stage and the total second stage were inversely correlated with both of their arterial and venous pH and BE (P < 0.01). However, further multiple regression analysis suggested that the correlation of the total second stage with the second twins' cord blood parameters could be solely explained by their own second stage. The rate of reduction in the second twins' arterial pH was 4.95 x 10(-3) per minute, and was significantly faster than that of the first twins', which was 1.55 x 10(-3) per minute (P < 0.05). CONCLUSIONS: During normal vaginal delivery, the umbilical cord blood gas status of both the first and the second twins deteriorated with the duration of their corresponding second stages, but the effects are greater in the latter. Furthermore, the duration of the first twins' second stage does not affect the blood gas status of the second twins'. These observations support the postulation of a diminished uteroplacental exchange function after the delivery of the first twin. Close monitoring and expeditious delivery of the second twins are important.

Adult↗

Perinatal outcome of vaginally delivered twin gestations with a larger twin B.

OBJECTIVE: To study the perinatal outcome of vaginally delivered twins when twin B is more than 250 g larger than twin A. STUDY DESIGN: Maternal and neonatal charts of live-born, nonanomalous twins, >25 weeks' gestation and vaginally delivered over a period of 17 years were reviewed. The results of this review were distributed among two groups: (1). those with twin B more than 250 g larger than twin A (DeltaBW>250) and (2). those where the difference was <250 g (DeltaBW<250). For vaginally delivered twin gestations, the perinatal outcome of twin B in the group DeltaBW>250 was compared to that of its co-twin, and to that of twin B in the group DeltaBW<250. RESULTS: Of the 679 twin gestations reviewed, 138 (20.6%) were in the group DeltaBW>250, of whom 73 (52.9%) delivered vaginally despite malpresentation in 39.7%. The vaginally delivered twin pregnancies in the groups DeltaBW>250 (n=73) and DeltaBW<250 (n=303) had similar demographics, parity, presentation, gestational age at delivery, and duration of the first stage of labor. Discordant twins were more frequent in the group DeltaBW>250 (26.0 versus 9.5%, p=0.001). Twin B in the group DeltaBW<250 was smaller, with higher incidence of growth restriction, low 5 min Apgar score, and hyperbilirubinemia compared to twin B in the group DeltaBW>250. There was no difference in the incidence of intraventricular hemorrhage, seizures, sepsis, neonatal death, and median nursery stay. Except for a lower median Apgar score at 1 min in twin B and a longer median nursery stay in twin A, twins A and B in the group DeltaBW>250 were similar regarding all other neonatal outcome variables. CONCLUSIONS: When twin B is more than 250 g larger than A, and both are delivered vaginally, the perinatal outcome is similar to its co-twin as well as to that of twin B of all other vaginally delivered twins. That twin B is larger than A is not itself a contraindication to attempted vaginal delivery.

Adult↗

Incidence, origin, and character of cerebral injury in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery.

OBJECTIVE: The objective of the study was to determine the incidence, origin, and character of cerebral lesions in monochorionic twins with twin-to-twin transfusion syndrome treated with fetoscopic laser surgery. STUDY DESIGN: This was a prospective study of monochorionic twins with twin-to-twin transfusion syndrome treated with fetoscopic laser surgery and monochorionic twins without twin-to-twin transfusion syndrome delivered at our center between June 2002 and September 2005, using cranial ultrasonography. RESULTS: Incidence of antenatally acquired severe cerebral lesions in the twin-to-twin transfusion syndrome group was 10% (8/84) and 2% (2/108) in the non-twin-to-twin transfusion syndrome group (P = .02). Incidence of severe cerebral lesions at discharge was 14% (12/84) in the twin-to-twin transfusion syndrome group and 6% (6/108) in the non-twin-to-twin transfusion syndrome group (P = .04). Antenatal injury was responsible for severe cerebral lesions in 67% (8/12) of the twin-to-twin transfusion syndrome group. CONCLUSION: Incidence of severe cerebral lesions in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery is high and results mainly from antenatal injury.

Brain Injuries↗

[Psychopathological study of twin schizophrenia from the viewpoint of twin interaction].

Schizophrenia research requires both genetical and environmental approaches. Some researchers have studied the environmental aspects of schizophrenia by comparing schizophrenic twins with non-schizophrenic ones in discordant pairs. But few studies have taken notice of the interaction between twins. This article focused on the unique relationship between twins, "inter-twin community", which might be considered one of the most important environmental factors. This study included 14 pairs of twins, 28 people including 17 schizophrenic patients. These inter-twin communities were divided into "close type" and "distant type" according to the closeness between the twins prior to the onset of schizophrenia. The close type, in which there was a high degree of closeness, included 8 pairs of twins, 16 people, 11 of whom were patients. The distant type, in which there was a low degree of closeness, included 5 pairs, 10 people, 5 of whom were patients. An additional sub-class of the close type was the "close-competitive type". This sub-type had a high degree of closeness and a high degree of competition, and included 1 pair, both of whom were patients. Eight out of the 11 patients in the close type (72.7%) had an excellent prognosis. In this type of inter-twin community the relationships gave patients a strong and stable protective environment. In the close-competitive type, the twins supported each other while one twin was having difficulty, but fought with each other when they recovered and eventually one twin relapsed, resulting in an alternating pattern of schizophrenic episodes. The twins were unable to separate from each other and they both had a poor prognosis; thus their relationship both provided the patients with a degree of protection and had a marked harmful effect. In the distant type, 4 of the 5(80%) patients had an poor prognosis. In this type, when one twin became ill, the other twin did not support them, and the relationship provided little protective effect, resulting in poor outcomes. The findings in this study support the idea that the nature of the inter-twin community has a strong influence on the course of schizophrenia in twins. Additionally, since all the female pairs belonged to the close type, and the male pairs tended to be the distant type, there are probable gender differences in the types of inter-twin communities. Finally, in making therapeutic plans for twin schizophrenics, it is very important to consider their relationship in terms of the inter-twin communities.

Adult↗

Individual placental territories after selective laser photocoagulation of communicating vessels in twin-twin transfusion syndrome.

OBJECTIVE: Intrauterine fetal death of one or both twins after laser therapy (selective photocoagulation of communicating vessels) may occur, in part, from insufficient individual placental mass. The objective of this study was to assess the percentage of individual placental mass (individual placental territory) that is associated with fetal survival in twin-twin transfusion syndrome after selective photocoagulation of communicating vessels. STUDY DESIGN: Placentas from 72 patients with selective photocoagulation of communicating vessels-treated twin-twin transfusion syndrome without intrauterine fetal death and from 61 monochorionic pregnancies without twin-twin transfusion syndrome (control subjects) were assessed. The placentas were weighed fresh (total placental mass) and cut along the vascular equator, which yielded the individual placental mass and the individual placental territory. Patency of anastomoses was ruled out with air-injection. The individual fetoplacental ratio was obtained by dividing birth weight by the corresponding individual placental mass. RESULTS: The 5th percentile individual placental territory that was associated with fetal survival was 27% in control subjects and 18% in cases with twin-twin transfusion syndrome, with a minimum of 10% to 14%, respectively. There were no differences in total placental mass, individual placental mass, individual placental territory, or individual fetoplacental ratio between pregnancies with twin-twin transfusion syndrome and control subjects. However, corrected for gestational age, the birth weight of recipient and donor twins were significantly smaller than control subjects. The individual placental territory of donors was statistically smaller than that of recipients. Individual placental territories were not different within control subjects. CONCLUSION: Fetal survival typically is associated with at least 18% of individual placental territory after selective photocoagulation of communicating vessels for twin-twin transfusion syndrome, but it can occur with as little as 10% to 14% individual placental territory. Decreased birth weight of the donor twin could result from relative decreased percentage of individual placental territory or from the loss of nutrients to the recipient twin. Decreased birth weight of the recipient twin could result from partial deprivation of functional placental tissue after surgery. Our findings may contribute to the understanding of normal and pathologic monochorionic twin gestations, in the counseling of patients, and potentially to the improvement of surgical treatment of twin-twin transfusion syndrome.

Adult↗

Twin-twin transfusion syndrome: etiology, severity and rational management.

The twin-twin transfusion syndrome is a serious complication of monochorionic twin pregnancies. Partly as a result of an inadequate understanding of the pathophysiology of the syndrome, there is a lack of consensus in clinical management. We sought to review the available information on the etiology of twin-twin transfusion syndrome, to identify parameters that contribute to the severity of the syndrome, and propose a rational management plan based on pathophysiology, clinical presentation and the efficacy of therapies. We therefore amalgamated recent advances in twin-twin transfusion syndrome computer modelling and clinical studies, particularly on therapeutic outcomes. We found that the oligo-polyhydramnios sequence that defines twin-twin transfusion syndrome prenatally represents a wide continuum of severity in the imbalance between the fetoplacental circulations of both twins. In severe twin-twin transfusion syndrome cases, in which the circulatory imbalance deteriorates beyond fetal control, fetoscopic laser therapy of all anastomoses along the placental vascular equator is predicted to have significantly better survival rates and fewer neurological sequelae than amnioreduction. In contrast, mild twin-twin transfusion syndrome cases have better outcomes after one or at most a few amnioreductions than laser therapy, as a result of significantly fewer procedure-related risks. In conclusion, optimal individual therapy may possibly achieve an 85% survival rate in twin-twin transfusion syndrome, but requires advancement in non-invasive criteria that predict the severity of the syndrome. Identifying such criteria is a future challenge. For the interim, twin-twin transfusion syndrome diagnosed before 26 weeks' gestation has significantly better survival rates and fewer neurological sequelae after laser therapy than amnioreduction. Twin-twin transfusion syndrome diagnosed after 26 weeks can best be treated by amnioreduction, or delivery. Contrary to previous claims, fetoscopic laser therapy has outgrown its experimental status. Although improvements in technique and technology are likely, laser placental ablation has a firm scientific and clinical basis.

Amniotic Fluid↗

Placental types and twin-twin transfusion syndrome.

OBJECTIVE: The purpose of this study was to assess the value of a proposed classification of monochorionic placenta in reference to twin-twin transfusion syndrome. STUDY DESIGN: The placentas from laser-treated patients with twin-twin transfusion syndrome and from uncomplicated monochorionic pregnancies that were delivered between January 1997 and December 2000 were included in the study. Placentas were classified as type A (no anastomoses), type B (only deep anastomoses), type C (only superficial anastomoses), and type D (deep and superficial anastomoses). The number and type of anastomoses were documented in each placental type. The severity of twin-twin transfusion syndrome was assessed in stages, as previously described. The relationship between placental types and the development and severity of twin-twin transfusion syndrome was determined. RESULTS: One hundred thirty-one placentas were examined. Twin-twin transfusion syndrome developed in 0% (0/4 placentas) of type A, in 100% (85/85 placentas) of type B, in 5.6% (1/18 placentas) of type C, and in 79.17% (19/24 placentas) of type D placentas. An average of 4.17 (range, 1-11) vascular anastomoses was found. The mean number of superficial anastomoses was not different between patients with twin-twin transfusion syndrome and patients with no twin-twin transfusion syndrome (1.6 vs 1.71, respectively; P =.69, Student t test). The presence or absence of superficial anastomoses was not associated with differences in the severity of twin-twin transfusion syndrome. CONCLUSION: This classification represents a practical approach to the surgical pathologic assessment of vascular anastomoses in monochorionic placentas, with a strong clinical correlation. It also allows for the clarification of the relationship between superficial anastomoses and twin-twin transfusion syndrome.

Arteriovenous Anastomosis↗

Cerebral palsy in the surviving twin associated with infant death of the co-twin.

BACKGROUND: Monozygotic twins are at greater risk of dying and of serious morbidity than dizygotic twins, and both are at greater risk than singletons. This is only partly explained by the higher proportion of low birthweight infants among twins. AIM: To compare, in same sex and different sex twins, birth weight specific neonatal death rates and cerebral palsy prevalence rates in the surviving twin when the co-twin has died in infancy. METHODS: Analysis of birth and death registration data for same sex and different sex twins for England and Wales 1993-1995 where both were live births. Death certificates of all liveborn twins who died were obtained from the Office for National Statistics. A questionnaire was sent to the general practitioners of all surviving co-twins to determine if the child had any disability. RESULTS: The neonatal death rate in same sex twins was 25.4 and in different sex twins 18.0 per 1000 live births (death rate difference 7.4; 95% confidence interval 4.7 to 10.1; p < 0.001). The higher neonatal death rate in same sex compared with different sex twins is attributable to the higher proportion of same sex twins with low birth weight. Prevalence of cerebral palsy in the low birthweight group (< 1000 g) was marginally higher in same sex (224 per 1000) than different sex (200 per 1000) twin survivors. In the birth weight group 1000-1999 g, same sex twin survivors were at a significantly higher risk of cerebral palsy than those of different sex: 167 v 21 per 1000; difference 145 (95% confidence interval 44 to 231; p < 0.01) per 1000 infant survivors. CONCLUSION: There are two components to the cause of cerebral palsy in twins. Immaturity per se predisposes to cerebral damage. Also, same sex twins may sustain cerebral damage that is in excess of that due to immaturity.

Birth Weight↗

Mortality among twins after age 6: fetal origins hypothesis versus twin method.

OBJECTIVE: To test the validity of the fetal origins hypothesis and the classic twin method. DESIGN: Follow up study of pairs of same sex twins in which both twins survived to age 6. SETTING: Denmark. SUBJECTS: 8495 twin individuals born 1870-1900, followed through to 31 December 1991. MAIN OUTCOME MEASURES: Mortality calculated on a cohort basis. RESULTS: Mortality among twins and the general population was not significantly different except among females aged 60-89, in whom mortality among twins was 1.14 times (SE 0.03) higher than in the general population. Mortality among female dizygotic twins was 1.77 times (0.18) higher than among monozygotic twins at age 30-59. Otherwise, mortality for monozygotic and dizygotic twins did not consistently differ after age 6. CONCLUSION: According to the fetal origins hypothesis the risk of adult morbidity and mortality is heightened by retardation in intrauterine growth. Twins, and in particular monozygotic twins, experience growth retardation in utero. The findings in the present study suggest that the fetal origins hypothesis is not true for the retardation in intrauterine growth experienced by twins. Furthermore, the data are inconsistent with the underlying assumption of a recent claim that the classic twin method is invalid for studies of adult diseases. The present study is, however, based on the one third of all pairs of twins in which both twins survived to age 6. The possible impact of this selection can be evaluated in future studies of cohorts of younger twins with lower perinatal and infant mortality.

Adolescent↗

Multifetal pregnancy reductions of triplets to twins: comparison with nonreduced triplets and twins.

OBJECTIVE: Multifetal pregnancy reduction has been shown to improve survival rates in high-order multifetal pregnancies (>/=4). There is, however, some controversy as to whether multifetal pregnancy reduction improves pregnancy outcomes of triplets reduced to twins. The purpose of this study was to evaluate this issue by comparing outcomes of triplet gestations undergoing reduction to twins with outcomes of nonreduced twin gestations and expectantly managed triplet gestations. STUDY DESIGN: The study included 143 triplet pregnancies that underwent reduction to twins over a 10-year period at a single center. These were compared with 12 nonreduced triplet pregnancies from the Wayne State University Perinatal Database and with 2 groups of twin pregnancies: 605 from the Wayne State University Perinatal Database and 207 from the Quest Diagnostics Database. RESULTS: The miscarriage rate for expectantly managed triplets was 25%, compared with 6.2% for triplets reduced to twins. This rate was similar to the rates for both groups of nonreduced twins: 5.8% (Quest) and 6.3% (Wayne State University). Severe prematurity occurred in 25% of nonreduced triplets compared with 4. 9% of twins after reduction. This rate was also similar to that of nonreduced twins: 7.7% (Quest) and 8.4% (Wayne State University). The mean gestational age at delivery for expectantly managed triplets (32.9 +/- 4.7 weeks) was significantly shorter than for triplets reduced to twins (35.6 +/- 3.1 weeks). By comparison, nonreduced twins had a mean gestational age at delivery of 35.8 +/- 3.9 weeks for Quest and 34.4 +/- 3.6 weeks for Wayne State University. Mean birth weights were significantly lower in expectantly managed triplets as compared with triplets undergoing reduction to twins (1636 +/- 645 g vs 2381 +/- 602 g, respectively). Nonreduced twins had a mean birth weight of 2254 +/- 653 g for Quest and 2123 +/- 634 g for Wayne State University. Pregnancy loss rates, mean length of gestation, and mean birth weight did not vary significantly between triplets who underwent reduction to twins and nonreduced twins. CONCLUSIONS: Reduction of triplets to twins significantly reduces the risk for prematurity and low birth weight and may also be associated with a reduction in overall pregnancy loss. This suggests that multifetal pregnancy reduction of triplets to twins is a medically justifiable procedure not only from an actuarial viewpoint but also from the ethical perspective of supporting patients' autonomy and respect for patients' individual circumstances.

Abortion, Spontaneous↗

Impacts of operative delivery for the first twin on neonatal outcomes in the second twin.

We assess the impacts of operative delivery for the first twins with vertex presentation on neonatal outcomes in second twins using the 1995 to 1997 twin registry data of the United States. A total of 102,554 eligible twin pairs with vertex presentation for the first twin were included in the analysis. Of these, 50,748 (49.5%) first twins had a normal vaginal delivery, 43,504 (42.4%) were delivered by cesarean section, and 8302 (8.1%) were delivered by vaginal operation (vacuum extraction or forceps). In term twins, the risks of asphyxia-related mortality (odds ratio [OR], 3.08; 95% CI, 1.07 to 8.45), newborn injury (OR, 2.10; 95% 1.39 to 3.12), low Apgar score at 5 minutes (OR, 1.49; 95% 1.24 to 1.78), and mechanical ventilation use (OR, 1.34; 95% 1.20 to 1.51) were increased in the second twins whose co-twins were delivered by vaginal operation compared with those whose co-twins who had normal vaginal delivery. In contrast, the risks of asphyxia-related mortality (OR, 0.55; 95% 0.17 to 1.57), newborn injury (OR, 0.20; 95% 0.11 to 0.34), low Apgar score at 5 minutes (OR, 0.51; 95% 0.44 to 0.60), and mechanical ventilation use (OR, 0.77; 95% 0.71 to 0.83) were decreased in the second twins whose co-twins were delivered by cesarean section compared with those whose co-twins had a normal vaginal delivery. In conclusion, vaginal operative delivery for the first twins is related to the adverse neonatal outcomes of their co-twins, whereas cesarean delivery for the first twins is associated with the beneficial neonatal outcomes of their co-twins.

Apgar Score↗

Natriuretic peptides in the pathogenesis of cardiac dysfunction in the recipient fetus of twin-twin transfusion syndrome.

OBJECTIVE: Although serial amnioreduction has substantially improved the prognosis of twin-twin transfusion syndrome, the majority of recipient twins develop cardiac dysfunction in utero and some have structural abnormalities in the neonatal period. The mechanism of cardiac dysfunction is unclear. To test the hypothesis that this occurs as a result of preload or pressure overload, we determined atrial natriuretic peptide and brain natriuretic peptide levels and their association with endothelin-1 in monochorionic pregnancies with or without chronic twin-twin transfusion syndrome. PATIENTS AND METHODS: Matched maternal and fetal blood samples were obtained in utero from monochorial twin pregnancies complicated with (n = 14) and without twin-twin transfusion syndrome (n = 6). Serial fetal echocardiography assessment included cardiac anatomy, chamber size, cardiothoracic ratio, ventricular thickness, and the presence and severity of atrioventricular valve regurgitation. Postnatal echocardiograms were obtained on the surviving twins. The plasma levels of atrial natriuretic peptide, brain natriuretic peptide, and endothelin-1 were measured by use of radio-immunoassay. RESULTS: Levels of fetal atrial natriuretic peptide (P <.001), brain natriuretic peptide (P <.001), and endothelin-1 (P <.001) in the recipient fetuses were higher than in donor twins. Fetal concentrations of atrial natriuretic peptide, brain natriuretic peptide, and endothelin-1 in the donor twins were similar to those concentrations in twins that did not have twin-twin transfusion syndrome. Fetal brain natriuretic peptide (P <.01) and endothelin-1 (P <.01) levels were significantly higher in the recipient fetuses when compared to those without severe cardiac dysfunction. A significant positive correlation was present between levels of fetal brain natriuretic peptide and endothelin-1 (y = 230.9 LOG(x) - 264.1, r =.82; P <.01). In contrast, there was no association between levels of fetal atrial natriuretic peptide and the severity of cardiac dysfunction, or with levels of fetal brain natriuretic peptide and endothelin-1. CONCLUSION: Fetal natriuretic peptide levels were higher in the recipient twins than the co-twins, and the severity of cardiac dysfunction was related to levels of brain natriuretic peptide. These data, thereby, suggest that brain natriuretic peptide is a sensitive surrogate biochemical marker of cardiac dysfunction in the recipient twin.

Atrial Natriuretic Factor↗