Multiple pregnancy. 2

General Principles for Counseling and Management of Triplet Pregnancies

Compared with singleton pregnancies, triplet pregnancies are associated with a significantly increased risk of adverse pregnancy outcomes. Early ultrasound examination is the best way to diagnose triplets, establish dating, and determine the number of placentas to provide appropriate counseling and monitoring. Dichorionic placentation adds risks specifically associated with a shared placenta, and limits options for intervention. Multifetal reduction is an option that can significantly improve pregnancy outcomes compared with non-reduced triplet pregnancies. Integration of a Maternal-Fetal Medicine specialist in the prenatal care for a triplet pregnancy reduces the risk of preeclampsia, preterm birth, low birthweight infants, perinatal mortality, and major neonatal morbidity.

Maternal, Perinatal and Neonatal Outcomes of Triplet Pregnancies According to Chorionicity: A Systematic Review of the Literature and Meta-Analysis

Triplet pregnancies are rare events that affect approximately 93 in 100,000 deliveries in the world, especially due to the increased use of assisted reproductive techniques and older maternal age. Triplet pregnancies are associated with a higher risk of fetal and maternal morbidity and mortality compared to twins and singletons. Chorionicity has been proposed as a major determinant of perinatal and maternal outcomes in triplet pregnancies, although further evidence is needed to clarify the extent and real influence of this factor. Thus, the aim of this study was to conduct a systematic review of the literature and a meta-analysis of the maternal and perinatal outcomes of triplet pregnancies, evaluating how chorionicity may influence these results. A total of 46 studies with 43,653 triplet pregnancies and 128,145 live births were included. Among the main results of our study, we found a broad spectrum of fetal and maternal complications, especially in the group of monochorionic and dichorionic pregnancies. Risk of admission to NICU, respiratory distress, sepsis, necrotizing enterocolitis, perinatal and intrauterine mortality were all found to be higher in non-TCTA pregnancies than in TCTA pregnancies. To date, our meta-analysis includes the largest population sample and number of studies conducted in this field, evaluating a wide variety of outcome measures. The heterogeneity and retrospective design of the studies included in our research represent the main limitations of this review. More evidence is needed to fully assess outcome measures that could not be studied in this review due to scarcity of publications or insufficient sample size.

Prevalence of common aneuploidy in twin pregnancies

The incidence of chromosomal abnormalities in twin pregnancies is not well-studied. In this retrospective study, we investigated the frequency of chromosomal abnormalities in twin pregnancies and compared the incidence of chromosomal abnormalities in dichorionic diamniotic (DD) and monochorionic diamniotic (MD) twins. We used data from 57 clinical facilities across Japan. Twin pregnancies of more than 12 weeks of gestation managed between January 2016 and December 2018 were included in the study. A total of 2899 and 1908 cases of DD and MD twins, respectively, were reported, and the incidence of chromosomal abnormalities in one or both fetuses was 0.9% (25/2899) and 0.2% (4/1908) in each group (p = 0.004). In this study, the most common chromosomal abnormality was trisomy 21 (51.7% [15/29]), followed by trisomy 18 (13.8% [4/29]) and trisomy 13 (6.9% [2/29]). The incidence of trisomy 21 in MD twins was lower than that in DD twins (0.05% vs. 0.5%, p = 0.007). Trisomy 21 was less common in MD twins, even when compared with the expected incidence in singletons (0.05% vs. 0.3%, RR 0.15 [95% CI 0.04–0.68]). The risk of chromosomal abnormality decreases in twin pregnancies, especially in MD twins.

Qualitative Investigation into Pre- and Post-Natal Experience of Parents of Triplets

Although parents of triplets experience substantial mental distress, research about this increasing population has primarily focused on physical health risks of triplets and mothers, failing to capture the subjective wellbeing of parents. Accordingly, this study aimed to understand first-hand experience of parents of triplets, using thematic analysis of semi-structured interviews participated by eight parents (four couples: Age M = 48.63, SD = 10.61 years). Six themes were identified: (1) Negative and (2) Positive experiences of raising triplets prenatally and postnatally, (3) Social, psychological, and material support, (4) Experiences and challenges specific to mothers and (5) fathers, and (6) Advice for future parents. These themes suggest that being reassured and accepting support from others are particularly essential in reducing stress and anxiety. Self-compassion interventions were recommended to support the wellbeing of parents of triplets. Our findings will help parents of triplets, their social circles, and healthcare workers to develop effective approaches to reduce the mental health difficulties that this under-researched population experiences.

Triplet pregnancy: What do we tell the prospective parents

Experience managing triplet pregnancies has increased over the past few decades as the incidence has changed related to assisted reproductive practices. Physicians caring for women carrying triplets cannot predict an individual outcome or pregnancy course but must educate patients about the challenges related to these high risk pregnancies. Obstetric providers can describe the wide range of risks associated with triplet gestations, and the general plan for management, but ultimately parents must make decisions with potentially lifelong consequences. Here, we present the diagnostic criteria, common complications, and management options for triplet pregnancies, to help obstetricians counsel patients on the medical and psychosocial consequences of triplet pregnancy, potential complications, and multifetal reduction.

Fetal cardiovascular hemodynamics in twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) complicates 10-15% of monochorionic-diamniotic (MCDA) pregnancies. It originates from unbalanced transfer of fluid and vasoactive mediators from one twin to its co-twin via placental anastomoses. This results in hypovolemia in the donor and hypervolemia and vasoconstriction in the recipient twin. Consequently, the recipient demonstrates cardiovascular alterations including atrioventricular valve regurgitation, diastolic dysfunction, and pulmonary stenosis/atresia that do not necessarily correlate with Quintero-stages. Selective fetoscopic laser photocoagulation of placental vascular anastomoses disrupts the underlying pathophysiology and usually improves cardiovascular function in the recipient with normalization of systolic and diastolic function within weeks after treatment. Postnatal studies have demonstrated early decreased arterial distensibility in ex-donor twins, but 10-year follow up is encouraging with survivors showing normal cardiovascular function after TTTS. However, prediction and appropriate early management of TTTS remain poor. Assessment of the cardiovascular system provides additional insight into the pathophysiology and severity of TTTS and may permit more targeted early surveillance of MCDA pregnancies in future. It should form an integral part of the diagnostic algorithm.

Obstetric outcomes of monochorionic pregnancies conceived following assisted reproductive technology: A retrospective study

OBJECTIVES:

The overwhelming numbers of twins following assisted reproductive technology (ART) are dichorionic twins, but monochorionic twins account for around 0.9% of post ART pregnancies. The data for post ART-monochorionic pregnancy outcomes are scarce due to the rarity of this condition. Hence, we evaluated the obstetric outcomes of monochorionic and dichorionic pregnancies conceived on ART.

SETTINGS:

University teaching hospital.

STUDY DESIGN:

A case–control study of monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) pregnancies conceived following ART treatment. Charts of all women who conceived following ART from 2008 to 2013 were screened. Among them, the monochorionic twins diagnosed in the first trimester were included and their obstetric outcome was followed-up. For comparison, an equal number of dichorionic twin pregnancies from age and body mass index matched mothers was selected.

RESULTS:

The baseline clinical characteristics were similar between the two groups. MCDA group had a higher miscarriage rate (50%) than the DCDA group (10%), with three seconds trimester miscarriages in the MCDA group. The live birth rates were lower in the MCDA versus DCDA group (40% vs. 90%). Among triplet pregnancies with a monochorionic component, the live birth rate was only 25%.

CONCLUSIONS:

Monochorionic pregnancies following ART have poorer obstetric outcomes when compared to dichorionic pregnancies. For monochorionic pregnancies following ART, intensive antenatal surveillance at a tertiary level obstetric and neonatal center may help optimize the outcome.

The Role of Ultrasound in Multiple Pregnancy

The advances in reproductive technologies have changed the demographics of multifetal pregnancies. In the first trimester, ultrasound allows to diagnose the number of multiples, chorionicity and amnionicity, the presence or absence of nuchal translucency, early growth discordance, severe malformations and the origin of activities and contacts between multiples. In the second and third trimester, the opportunity to examine the cervix by transvaginal ultrasound should not be missed to detect the risk of premature delivery. Ultrasound is essential for the early grading and treatment of twin-to-twin transfusion syndrome (TTTS), the diagnosis of malformations and growth disturbances. Doppler velocimetry has proven to be able to reduce perinatal mortality in twin pregnancies. Finally, ultrasound is used for the detection of the position of multiples and the decision of the optimal route of delivery. This is of main importance in delayed interval delivery and expectant management of multifetal pregnancies and early cervical dilatation.

Ultrasound diagnosis of dicephalic conjoined twins at 24 weeks of gestation

We report the case of dicephalic conjoined twins discovered incidentally on a routine ultrasound at 24 weeks of gestation. There were 2 heads and a neck that fused with 1 thorax, but the spines continued all the way to the coccyx. The spines were connected medially by a fused rib, and laterally, there were ribs that went around the thorax in a more normal fashion. Antenatal ultrasound images are supplemented by postnatal photographs and x-rays.

Early prenatal diagnosis of conjoined twins at 7 weeks and 6 days' gestation with two-dimensional Doppler ultrasound: a case report

This case report presents the prenatal diagnosis of conjoined twins at 7 weeks and 6 days’ gestation according to the last menstrual period and 6 weeks and 4 days’ gestation according to crown-rump length in a 32-year-old Turkish woman, using two-dimensional Doppler ultrasound. The twins were fused to each other at the thoracic region (thoracopagus). In the light of previous reports of conjoined twins this appears to be one of the earliest prenatally diagnosed cases in the medical literature.

Multiple gestations: the importance of ultrasound

The use of ultrasound in the diagnosis of twins, its role of determining chorionicity, the management of unique twin complications, the value of cervical length determination in twins, the use of ultrasound in screening for aneuploidy in multiples, and the intrapartum role of ultrasound in twin gestations have been reviewed. The availability of high-resolution ultrasound has significantly im-proved the management of multiple gestations.

Twinning

Twinning has fascinated human beings over the centuries. New technologies and large study groups have led to improved documentation of frequency and complications in twin pregnancies and long-term outcomes. Artificial reproductive technologies have led to a pronounced rise in numbers of dizygotic and monozygotic twins. Although spontaneous dizygotic twinning is clearly associated with increased concentration of follicle-stimulating hormone and ovulation of more than one egg, causes of monozygotic twinning remain illusive. Twin studies are used increasingly to study complex traits and disorders: however, caution is suggested, since twins might not be representative of a typical singleton pregnancy. Monozygotic twinning seems to represent an anomaly in itself, with an increased number of spontaneous abortions and structural congenital anomalies. Both monozygotic and dizygotic twins have growth rates that slow at 30 weeks in utero and might be programmed both developmentally and biochemically earlier in pregnancy to have different responses at birth and after birth compared with singletons.

Intrapartum management of multifetal pregnancies

Over the past several decades advances in assisted-reproductive technologies have resulted in a dramatic increase in the number of multifetal gestations. Concomitant with this increase there has been a gradual rise in the overall preterm birth rate, as well as other pregnancy complications related to these pregnancies. Twin, triplet, and other high-order multifetal gestation pregnancies pose a number of important issues related to antepartum and intrapartum management. Antepartum issues include ultrasound determination of zygosity, management and prevention of preterm labor, maternal/fetal surveillance for complications, and specific interventions focused on prevention of adverse maternal and/or fetal outcomes. Intrapartum issues include those related to timing of delivery, labor management, anesthesia options, and determination of an optimal delivery modality. Clearly, these issues related to the management of multifetal pregnancies are of paramount importance to optimize pregnancy outcome. As many of the issues related to antepartum care for women with multifetal gestations have been reviewed elsewhere, we have restricted the focus of this article to intrapartum management. Thus, this article reviews salient issues related to the intrapartum management of multifetal gestations, including twins, triplets, and other high-order pregnancies.

Is hemifacial microsomia linked to multiple maternities?

Hemifacial microsomia describes a congenital orofacial malformation in which there is insufficient or disrupted development of the mandible affecting one side of the face. The aetiology of this condition remains unclear, but it has been postulated that twins (predominantly monozygotic) are more liable to be affected than singletons. This study investigates the incidence of multiple births amongst a large number of affected individuals and their families. Data were collected on 145 individuals with hemifacial microsomia and microtia, using postal questionnaires and interviews in a hospital setting. These data were compared with the mean age-standardised twin maternity prevalence for England and Wales between 1975 and 1995 of 1.06% and the triplet maternity prevalence for England and Wales for 1995 of 0.034% (a multiple maternity being where more than one baby is born, either alive or stillborn). The prevalence of twin maternities amongst the affected individuals was 3.96% (P>0.05) and amongst their siblings it was 4.02% (P<0.02). There was also an excess of twins in the rest of the family groups, predominantly due to a stronger history of twinning on the maternal side. As there were more twins amongst the affected individuals than in the general population, it seems likely that whatever the aetiology of hemifacial microsomia and microtia, the presence of a co-twin (or co-triplets) may make the causal event, or series of causal events, more likely to occur. This study supports the hypothesis that hemifacial microsomia and microtia are in some way linked to multiple births. Analysis of this link may provide new directions for research into the aetiology of a variety of congenital defects.

Monozygotic twins following blastocyst transfer: a report of two cases

Several studies have shown an increased risk for monozygotic twinning after fertilization treatments. We present the clinical and sonographic characteristics of two monozygotic twin cases following blastocyst transfer. It is suggested that delayed transfer of the embryo in the blastocyst stage is a contributing factor to monozygotic twinning.

Congenital vertebral anomalies in ischiopagus and pyopagus conjoined twins

A review of clinical records and radiographs revealed that five of 10 patients with conjoined twinning (three of six ischiopagus and two of two pyopagus twins) had congenital vertebral anomalies including hemivertebrae (3), multiple thoracic anomalies (1), right hemisacral agenesis (1), and three lumbar vertebra (1). No mirror image anomalies were identified, and different regions of the spine were involved in the two cases in which both twins had anomalies. Coexisting visceral and musculoskeletal anomalies included dextrocardia (3), atrial septal defect (1), congenital vertical talus (2), Sprengel's deformity (1), and multiple unilateral foot anomalies (1). Hip subluxation or dislocation was seen in five of eight ischiopagus or pyopagus twins after separation and required femoral and pelvic osteotomies. Lumbar scoliosis not associated with congenital vertebral anomalies was seen in two ischiopagus twins. These observations suggest an association between ischiopagus and pyopagus conjoined twins and congenital vertebral anomalies, and their coexistence is explained best by a nonspecific teratogenic insult during early embryogenesis.

Parasitic conjoined twins: a case report

Parasitic twins are a rare phenomenon and a challenge for caregivers. Occurring as a result of abnormal processes in the first several weeks of embryologic development, this condition is oftentimes diagnosed by prenatal ultrasound. This unusual condition may go undiagnosed until the time of delivery, however, despite the availability and use of advanced ultrasound techniques. The challenges presented by this condition are multiple and complex. The following case report demonstrates some of these challenges.

High rate of twins among offspring of mothers with the Järvi-Hakola-Nasu disease and with comments on disorders associated with twinning

Finnish mothers with Jrvi-Hakola-Nasu disease, progressive dementia with lipomembranous polycystic osteodysplasia (McKusick 221770) have a high rate of twin maternities, 128.2/1000. The exact 99% confidence intervals are 28.7-322.2/1000, thus above the average twinning rate in Finland, i.e. 15/1000. This eightfold increase in twinning may be an indication of a disturbed cortico-hypothalmic-hypophyseal axis or an other premorbid hormonal imbalance. It is concluded that even if dizygotic twinning is as a rule an event in itself, not only iatrogenic factors, as ovulation inducers, etc., but also some genetic disorders may be associated with twinning. More studies are needed to elucidate the incidence of twinning in families with these disorders.

Sonographic determination of first trimester twin chorionicity and amnionicity

OBJECTIVE

To determine the reliability of first trimester sonography in the detection of twin chorionicity and amnionicity.

MATERIALS AND METHODS

Sets of twins (179) were evaluated sonographically in the first trimester. Chorionicity was determined by identifying the number of gestational sacs. The presence or absence of an amnion about each embryo/fetus was also recorded. The placentas for each case were evaluated to determine chorionicity and amnionicity.

RESULTS

Of the 179 twin pairs, 158 were dichorionic/diamniotic; 19 were monochorionic/diamniotic, and two pairs were monochorionic/monoamniotic. Chorionicity and amnionicity were correctly determined in each case.

CONCLUSION

The chorionicity of twin pregnancies can be determined from the time that the gestational sacs are visualized within the uterus. Transvaginal sonography can reliably determine the amnionicity of monochorionic twin pregnancies after 7 weeks, menstrual age.

The biology of the twinning process: how placentation influences outcome

Placentation of twins has important bearing on the fetal development and neonatal outcome. Because of limitation in space of the endometrial cavity, twin placentas frequently collide during their expansion. This may restrict their growth and also lead to a somewhat increased rate of placenta previa. Moreover, abnormal cord insertions such as marginal and velamentous cords are much more frequent in multiple gestation. Absence of one umbilical artery is also much more frequent in twins. The best prognosis is had when two independent placentas develop, the dichorionic separate organs. Fusion of two separate placentas does not lead to vascular anastomoses in human twins, whereas it often does in other species (marmoset, cattle). Blood vessel fusion occurs only in monochorionic twins, all of which are "identical" (monozygotic). Large anastomoses (usually artery-to-artery) allow blood to shift rapidly from one to the other. Thus, when one twins dies, the survivor may quickly exsanguinate into the dead twin, leading to hypotension and occasionally to cerebral palsy. Arteriovenous anastomoses are the basis for the twin transfusion syndrome. This results in severe prematurity and gross discordance of all sorts of physical parameters. Knowing this type of vascular shunts helped develop the prenatal laser obliteration with salvage of the twins. The worst prognosis occurs with the rarest type of placentation in twin, in which both reside in the same cavity. This is the monoamnionic-monochorionic twin placentation. By moving about, the twins often entangle their umbilical cords and some 40% to 50% may die in utero.

Listeriosis: a previously unreported medical complication in women with multiple gestations

OBJECTIVE

Our purpose was to determine whether women pregnant with multiple gestations are at greater risk for perinatal listeriosis than are women pregnant with singletons.

STUDY DESIGN

Active surveillance for perinatal listeriosis was carried out in Los Angeles County, California, medical records were reviewed, and rates of listeriosis were calculated from live birth and fetal death data.

RESULTS

From January 1985 through December 1992, 12 (4.0%) of 301 perinatal listeriosis cases occurred in pregnant women with multiple gestations, almost four times the overall multiple gestation rate in Los Angeles County. Rates of listeriosis in pregnant women per 100,000 live births and fetal deaths were 19.8 for singleton and 74.9 for multiple gestations (risk ratio 3.8, 95% confidence interval 2.1 to 6.8). Compared with singleton pregnancies, greater risk of listeriosis was observed in pregnancies with triplet gestations (risk ratio 38.4, 95% confidence interval 9.6 to 153.3) than in those with twin gestations (risk ratio 3.2, 95% confidence interval 1.7 to 6.0). Increased risk of listeriosis during multiple-gestation pregnancies was most notable among women > or = 35 years (risk ratio 13.6, 95% confidence interval 5.2 to 35.5) and Hispanic women (risk ratio 5.3, 95% confidence interval 2.8 to 10.0).

CONCLUSIONS

To reduce the risk of listeriosis, obstetricians should incorporate dietary recommendations into routine prenatal nutritional counseling for all pregnant women and should especially counsel women pregnant with multiple gestations of their greater risk.

Early and simple determination of chorionic and amniotic type in multifetal gestations in the first fourteen weeks by high-frequency transvaginal ultrasonography

OBJECTIVE

Our aim was to determine the chorionic and amniotic types in multifetal pregnancies with transvaginal ultrasonography at > or = 14 weeks' gestation.

STUDY DESIGN

Two hundred twelve multifetal pregnancies were scanned transvaginally at or before 14 weeks' gestation. The number of fetuses and the chorionic and amniotic type were determined ultrasonographically. Of the 212 patients, 54 were delivered at our institution, and 43 of these 54 had pathologic evaluation of the placenta. Ultrasonographic and pathologic correlation of the chorionic and amniotic type was assessed in this group.

RESULTS

Ultrasonographic evaluation of the 212 pregnancies demonstrated 64 twin, 87 triplet, 41 quadruplet, 18 quintuplet, 1 sextuplet, and 1 septuplet gestation. Nine of the twin pregnancies were monochorionic-diamniotic; two of the triplets were dichorionic-triamniotic, and four of the quadruplets were trichorionic-quadraamniotic. In the 43 patients with both ultrasonographic and pathologic assessment, there were 40 twins, five of which were monochoronic diamniotic type. All three triplets were trichorionic-triamniotic type. In all 43 transvaginal ultrasonography correctly predicted the chorionic and amniotic type as determined by the pathologic findings.

CONCLUSIONS

Transvaginal ultrasonography at < or = 14 weeks can easily and accurately determine the chorionic and amniotic type in multifetal pregnancies.

Twin growth problems: causes and sonographic analysis

Understanding the significant increased risks associated with twin pregnancies requires knowledge of the embryogenesis of twins and the unique placental characteristics seen only in twin gestations. Dizygotic "fraternal" twins, 70% of all twins, are at relatively low risk when compared with monozygotic twins, largely due to abnormalities seen in association with monochorionic placentation. The sonographic determination of chorionicity and amnionicity allows better estimation of pregnancy risk--up to 50% mortality in monochorionic-monoamniotic twins. Careful evaluation of intrauterine twin growth assists in the early identification of fetal abnormalities because normal twin growth should parallel that of singleton pregnancies until late in the third trimester. A number of the unique complications affecting growth in twin pregnancies are discussed, including twin transfusion syndrome, the "stuck twin" phenomenon, twin embolization syndrome, and development of acardiac twins.

Cerebral palsy in twins

Eighty-six children with cerebral palsy (CP) born as a product of twin pregnancies were studied. Data regarding their co-twins were also gathered. The authors' findings suggest that (1) monozygotic twins have a higher risk of CP than dizygotic twins, (2) twin order at birth does not seem to be a relevant factor in the etiology of CP, (3) mothers less than 24 or more than 34 years of age had the highest incidence of children with CP as a product of a twin pregnancy, and (4) the data do not support a genetic basis for the disease.

Disseminated herpes simplex infection in a twin: the role of the "stat" autopsy in immediate therapeutic intervention for survival of multiple birth neonates

Multiple birth neonates are unique in sharing similar intrauterine, and commonly the extrauterine, environments. The development of an infectious disease in one infant during the perinatal period assumes special significance in this setting, and the other siblings are often at high risk for a similar disease. Under these circumstances it is important to make a rapid etiologic diagnosis to provide appropriate therapeutic intervention. The immediate, or "stat", autopsy is a diagnostic modality involving the use of multiple procedures for the rapid diagnosis of perinatal infection which may be lifesaving in the setting of multiple birth neonates. This report describes the use of the "stat" autopsy to diagnose a fatal case of disseminated herpes simplex infection in a twin, which lead to the immediate treatment of the surviving sibling with appropriate antiviral medication.

Placental emboli from a fetus papyraceous

A syndrome in monozygotic twins that consists of a macerated twin fetus (fetus papyraceous) and a live-born twin with various anatomical defects has been described. The etiology is thought to be placental transfer of emboli or thromboplastic material through vascular shunts. Thromboplastic material precipitates disseminated intravascular coagulation (DIC) in the fetus, with a resultant hypercoagulable state due to relative fetal antithrombin III deficiency. Two cases of this syndrome will be discussed. The case of a live-born twin with intestinal atresia, who developed in utero with a fetus papyraceous, is reported. Emboli were demonstrated in vascular shunts of the diamniotic-monochorionic placenta. The hypothesis of intestinal atresia as a result of a vascular accident is reviewed. Another case involving a live-born twin with congenital skin defects, who developed in utero with a fetus papyraceous, is also reported. The skin defects were a congenital disruption from fetal DIC with resultant hypercoagulable state. Several other manifestations of the placental emboli syndrome will be discussed and the vascular etiology of the disruptions explained.

Separation of conjoined twins

The incidence of conjoined twins is rare, occurring in one in 50-80,000 live births. The rarity of the occurrence presents quite a management challenge. The first case in New Zealand of successfully separated thoraco-omphalagus twins, presenting top-to-tail, is described.

Fetal blood sampling demonstrating chimerism in monozygotic twins discordant for sex and tissue karyotype (46,XY and 45,X)

Fetal blood sampling has been used in the genetic work-up of twin gestations for rapid karyotyping. We present a case of twins which on ultrasound evaluation revealed hydrops fetalis in one twin and a normal second twin. Fetal blood sampling revealed the presence of mosaicism for 46,XY/45,X in both twins. HLA antigen testing showed the twins to be identical. The patient elected pregnancy termination. Blood chromosomal analysis after delivery revealed both twins to have 46,XY/45,X mosaicism, but the twin with signs of hydrops fetalis had tissue chromosomes of 45,X and the normal twin had tissue chromosomes of 46,XY. Amniotic fluid chromosomal analysis revealed 46,XY in twin A and 45,X in twin B. This represents a case of identical (monozygotic) twins with sex discordance. In this case, there was the probable occurrence of post-zygotic chromosomal non-disjunction leading to the discordancy of the sex in this set of twins. With the presence of vascular communication in monozygotic twins, there is the possibility of exchange of blood in monozygotic twins and the result of blood chimerism in twins.

Ultrasonographic criteria for the prenatal diagnosis of placental chorionicity in twin gestations

Thirty-two patients with uncomplicated twin pregnancies had ultrasonographic examinations for genetic amniocentesis, confirmation of twinning, or assessment of fetal growth. The dividing membranes between the fetuses were visualized, and the thickness of the membranes was measured. With a thickness of 2 mm used as a cutoff point, the accuracy in predicting monochorionic or dichorionic twinning was 82% and 95%, respectively. Prenatal assessment of these dividing membranes may be helpful in the management of twin gestations.

Neodymium:yttrium-aluminum-garnet laser occlusion of rhesus placental vasculature via fetoscopy

We tested the feasibility of photocoagulating placental vascular communications with a fetoscopically delivered neodymium:yttrium-aluminum-garnet laser in 12 pregnant monkeys in the second trimester. The technique was successful in eight cases. One ended in spontaneous labor 2 weeks after occlusion and one stillbirth occurred at term. Six live fetuses were delivered at term, with all treated vessels demonstrating occlusion. There was minimal placental damage at the laser impact sites, and no fetal abnormalities were detected. Long-term occlusion of placental vasculature can be accomplished by fetoscopically delivered laser energy.

Management of twin pregnancy: the vaginal route is still safe

To investigate the effect of method of delivery on the outcome of twin pregnancies, we reviewed all deliveries at our institution over the 10 years from 1976 to 1985. Two hundred six pairs were delivered, with a mean gestational age of 34 weeks (range 20 to 43 weeks) and a mean weight of 2116 gm (range 220 to 3800 gm). The mean gestational age at diagnosis of the twin pregnancy was 23 weeks. Nineteen (4.6%) infants were stillborn, and 36 (8.7%) died in the neonatal period. Cesarean section was used to deliver both twins in 66 cases. The method of delivery for the remaining 142 cases was vaginal-vertex, 85 (61%), vaginal-breech, 40 (29%), cesarean section, 13 (9%), and version and extraction, 2 (1%). The four most common indications for cesarean section for both twins were previous cesarean section, breech presentation, abnormal labor, and fetal distress. The indications for the 13 cesarean sections after vaginal delivery of twin A were fetal distress, cord prolapse, high presenting part, and footling breech. The impact of the method of delivery was investigated by comparing outcome variables between twin pairs. No significant differences were noted for perinatal mortality, need for resuscitation, duration of newborn hospital stay, and trauma. There were significant differences in the 1- and 5-minute Apgar scores in the vaginal delivery group. These differences were clinically minor, tending toward mild acidemia, and were unaffected by route or method of delivery.

Aneuploidy and the fragile X syndrome

The possibility that female carriers of the fragile X gene(s) are at increased risk for nondisjunctional events leading to aneuploid offspring has been suggested by several investigators. To better address this question we analyzed pedigrees of 117 families in which the fragile X syndrome is segregating. The 117 pedigrees, originally collected for segregation analyses, included 236 females with offspring whose carrier status was determined by cytogenetic or pedigree analysis or by analyses using flanking DNA markers. These 236 females have had 931 offspring including one 47,XXY and 6 trisomy 21 individuals (1/155). Statistical analysis suggested that the observed rate of trisomy 21 was significantly higher than expected (Fisher's exact test, p less than or equal to 0.05). Assuming a Poisson distribution to calculate the confidence interval for the observed rate of trisomy 21 individuals, we found that the expected rate of 1.6/1000 in this sample fell outside the 99% confidence limits of our observed rate of 1/155. Additional data from a larger sample are needed to replicate these findings.

Monozygotic Turner syndrome twins--correlation of phenotype severity and heart defect

We report on monozygotic twins with Turner syndrome (45,X) with discordant phenotypes. One twin had severe neck webbing and extremity edema and died of severe coarctation of the aorta. The other twin had fewer craniofacial anomalies and no congenital heart defect, suggesting a pathogenetic relationship between cardiac abnormality and phenotype severity.

Multiple pregnancy in the Maltese population

This study analyses the multiple birth statistics for the Maltese Islands since 1959. Hospital twin births delivering during the period of 1983-1985 are analysed for a number of variables. The incidence of multiple pregnancy for the Maltese Islands appears to have decreased slightly since 1959 with an overall rate of 10.21 per 1000 maternities. The ratio of dizygotic to monozygotic twinning was computed to be 1.64. Patients with multiple pregnancies are shown to be generally elderly and multiparous. The pregnancy outcome is more likely to be complicated by an operative delivery, while the infant is more likely to be premature and of low birth weight. The perinatal mortality rate for multiple pregnancies is markedly in excess of that for singleton births.

Simple ectopia of the kidney in monozygotic twins

We report a case of simple ectopia of the kidney in monozygotic twins. The hypothesis of a genetic mechanism for renal dysmorphogenesis could be tested by banking autopsy tissue and analyzing the messenger ribonucleic acid.

Birthweight differences, the transfusion syndrome and the cognitive development of monozygotic twins

Monochorionic twins may differ from dichorionic monozygotic (MZ) twins because of the transfusion syndrome and the timing of the cleavage of the zygote. Intrapair birthweight differences may be an indicator of these intrauterine variables. Previous evidence concerning weight differences and intellectual ability in MZ twins is reviewed with recommendations that future research also incorporates full placental data. Poorer scores on a nonverbal test are found for the lighter male twin of pairs with large intrapair differences in birthweight. Co-twin concordance rates for test scores are also highest for this group indicating that they vary consistently from other groups. Some evidence is presented from the present and earlier studies implicating anomalies of asymmetry or the transfusion syndrome as possible causes of these differences in brain functioning. The study adds further doubts as to the validity of any assumption of developmental equivalence between MZ twins and the general population.

An acardiac acephalic monster

A case of an acardiac acephalic monster is described, and the literature concerning the incidence, classification and etiology of acardia is reviewed. Acardia is a very rare congenital anomaly occurring in less than 1 in 34600 deliveries. The acardiac monster has been reported only in multiple, monochorionic pregnancies. This bizarre anomalous fetus is sustained in utero by parasitic anastomoses to the circulation of its usually normal co-twin and is therefore not compatible with extrauterine survival. Possibilities for prenatal diagnosis and complications during pregnancy and delivery are considered.

Increased child abuse in families with twins

Close spacing of children may be a significant risk factor for subsequent abuse in some families. Twin births are an extreme example of close spacing. Therefore, the authors hypothesized that twin births may predispose to an increased incidence of child abuse. Thirty-eight families with twins were compared with 97 single birth families and matched for birthdate, maternal age, race, and socioeconomic status. Families with twins experienced a significantly higher incidence of child abuse and neglect than did those with single births (p less than .003). A written questionnaire designed to study mothers' feelings and perceptions of support systems showed a significant difference only in greater difficulty in feeding twins as compared with single infants (p less than .001). Mothers of abused children were more likely not to answer the questionnaire at all (p less than .005). Neither mothers of single births nor those of twins felt that health professionals provided adequate education or support following the birth of their infants.

Monozygotic twins discordant for trisomy 21

Monochorionic twins were phenotypically discordant for Down syndrome. Chromosome analysis of lymphocytes showed both to be mosaics. Fibroblast chromosome analysis showed that one twin was 46,XY and the other 47,XY, +21. Blood mosaicism appears to have resulted from placental anastomoses. The twins are presumed to be monozygotic on the basis of placentation, identical blood groups, HLA haplotypes, and serum proteins. We offer some speculation on the manner of occurrence of this rare event.

Multiple pregnancy and fetal abnormalities in association with oral contraceptive usage

1,000 multiple births were examined in relation to maternal exposure to an oral contraceptive before conception. There was a significantly higher rate of monozygotic twinning among pregnancies which took place within 6 months of cessation of the contraceptive. In the monozygotic group there was a significant increase in the incidence of congenital abnormalities (P less than 0.01) when conception occurred within 3 months of cessation of the contraceptive.

Female pseudohermaphroditism in conjoined twins. Case report

A case of female pseudohermaphroditism in ischiopagus conjoined twins is presented and discussed.