Dichorionic Triplet Pregnancy Research Articles

Intertwin nuchal translucency difference predicts the chance of co-twin death after fetal reduction in dichorionic triplet pregnancies: a retrospective analysis study

ObjectivesTo compare the clinical outcomes of different multifetal pregnancy reduction (MFPR) programs in dichorionic (DC) triplets, and explore the association between early ultrasound characteristics and co-twin death after potassium chloride (KCl) injection into one monochorionic (MC) twin.MethodsWe retrospectively reviewed the data of DC triplets who underwent MFPR at our center during 2012–2021. Patients were grouped as follows: intracardiac KCl injection into one MC twin (group A), intracardiac KCl injection into both MC twins simultaneously (group B), and reduction of the singleton fetus (group C) and pregnancy outcomes were compared. Logistic regression was used to determine whether ultrasound measurements at 11–13+6 weeks predicted co-twin death and the receiver operator characteristic (ROC) analysis was conducted to assess the predictive performance.ResultsFinally, we enrolled 184 patients. 153 cases were in group A, and 18, 13 cases were in group B and C respectively. Gestational age at the time of MFPR did not differ among the 3 groups (median: 12^frac67 weeks). The survival rate was 89.6%, 88.9%, and 92.3% in group A, B, and C respectively, which was comparable among groups. Preterm birth was more common in group C (10/12, 83.3%). After KCl injection into one MC twin, co-twin death occurred in 86.3% cases (132/153) within 1 day; however, 3 patients had 2 live births each, with normal postnatal development. Intertwin nuchal translucency (NT) difference/discordance significantly predicted co-twin death within 1 day after MFPR, and the areas under the ROC curve were 0.694 and 0.689, respectively.ConclusionsFor MFPR in DC triplet pregnancies, reduction of the MC twins results in less preterm birth, and women with KCl injection into either one or both MC twins had similar outcomes. Large intertwin NT difference/discordance was associated with co-twin death within 1 day after KCl injection into one of the MC twins.

Conjoined twins in dichorionic diamniotic triplet pregnancy: a report of three cases and literature review

BackgroundConjoined twins are a rare and serious complication of monochorionic twins. The total incidence is 1.5 per 100,000 births, and about 50% are liveborn. Prenatal screening and diagnosis of conjoined twins is usually performed by ultrasonography. Magnetic resonance imaging can be used to assist in the diagnosis if necessary. Conjoined twins in dichorionic diamniotic triplet pregnancy are extremely rare.Case presentationWe reported three cases of dichorionic diamniotic triplet pregnancy with conjoined twins. Due to the poor prognosis of conjoined twins evaluated by multidisciplinary teams, selective termination of conjoined twins was performed in three cases. In case 1, selective reduction of the conjoined twins was performed at 16 gestational weeks, and a healthy female baby weighing 3270 g was delivered at 37 weeks. In case 2, the conjoined twins were selectively terminated at 17 weeks of gestation, and a healthy female baby weighing 2760 g was delivered at 37 weeks and 4 days. In case 3, the conjoined twins were selectively terminated at 15 weeks and 2 days, and a healthy female baby weighing 2450 g was delivered at 33 weeks and 6 days. The babies of all three cases were followed up and are in good health.Conclusion(s)Surgical separation is the only treatment for conjoined twins after birth. Early determination of chorionicity and antenatal diagnosis of conjoined twins in triplet gestations are critical for individualized management options and the prognosis of normal triplets. Expecting parents should be extensively counseled by multidisciplinary teams. If there are limitations in successful separation after birth, early selective termination of the conjoined twins by intrathoracic injection of potassium chloride may be a procedure in dichorionic diamniotic triplet pregnancy to improve perinatal outcomes of the normal triplet.

Ovarian hyperstimulation syndrome in a frozen-thawed embryo transfer pregnancy: a rare case report

BackgroundOvarian hyperstimulation syndrome (OHSS) is an iatrogenic complication of ovarian stimulation. Prevention and early recognition of OHSS are important to ensure patient safety.Case presentationIn this case, we reported a patient who underwent controlled ovarian hyperstimulation (COH) and in vitro fertilization (IVF). All embryos were cryopreserved to reduce possible OHSS. However, OHSS still occurred after the patient had a frozen-thawed embryo transfer (FET) with hormone replacement therapy (HRT) and obtained a dichorionic diamniotic triplet pregnancy. After multifetal pregnancy reduction (MFPR) and supportive treatment, all the symptoms regressed.ConclusionsPrompt recognition of OHSS, especially in patients who have no history of ovulation induction and fresh embryo transfer, is very important. Multiple pregnancies may lead to severe OHSS because of the high level of human chorionic gonadotropin (hCG) in the early stages. We suggest that a single embryo transfer may be necessary and beneficial for patients.

Pregnancy outcome after multifetal pregnancy reduction of triplets to twins versus reduction to singletons.

Does fetal reduction of triplet pregnancies to singleton result in superior obstetric and neonatal outcomes compared with triplets reduced to twins? A historical cohort study including 285 trichorionic and dichorionic triplet pregnancies that underwent abdominal fetal reduction at 11-14 weeks in a single tertiary referral centre. The study population comprised two groups: reduction to twins (n = 223) and singletons (n = 62). Main outcome measures were rates of pregnancy complications, preterm delivery and neonatal outcomes. Non-parametric statistical methods were employed. Triplet pregnancies reduced to twins delivered earlier (36 versus 39 weeks, P < 0.001) with higher prevalence of Caesarean section (71.1% versus 32.2%, P < 0.001) compared with triplets reduced to singletons. Preterm delivery rates were significantly higher in twins compared with singletons prior to 37 weeks (56.9% versus 13.6%, P < 0.001), 34 weeks (20.2% versus 3.4%, P = 0.002) and 32 weeks (9.6% versus 0%, P = 0.01). No significant difference was found in the rate of pregnancy loss before 24 weeks (1.3% in twins versus 4.8% in singletons, P = 0.12) or in the rate of intrauterine fetal death after 24 weeks (0.4% versus 0%, P = 1.0). Both groups had comparable obstetrical complications and neonatal outcomes, except for higher rates of neonatal intensive care unit admission in twins (31.9% versus 6.8%, P < 0.001). Reduction of triplets to singletons rather than twins resulted in superior obstetric outcomes without increasing the procedure-related complications. However, because the rate of extreme prematurity in pregnancies reduced to twins was low, the overall outcome of those pregnancies was favourable. Therefore, the option of reduction to singletons should be considered in cases where the risk of prematurity seems exceptionally high.

Clinical outcomes of multifetal pregnancy reduction in trichorionic and dichorionic triplet pregnancies: A retrospective observational study

ObjectiveTo observe the pregnancy and perinatal outcomes of trichorionic triplet (TCT) and dichorionic triplet (DCT) pregnancies with or without multifetal pregnancy reduction (MFPR). Materials and methodsThis was a retrospective study of 732 TCT and 118 DCT pregnancies after IVF/ICSI cycles between October 1999 and May 2014 at the Reproductive & Genetic Hospital of CITIC-Xiangya. The TCT and DCT groups were subdivided into three subgroups: MFPR to single fetus group, MFPR to twins group and expectant group. Pregnancy and perinatal outcomes were compared between different subgroups. ResultsThe resulting subgroups were TCT-Expectant (n = 40), TCT to twin (n = 610), TCT to single (n = 22), DCT-Expectant (n = 17), DCT to twin (n = 50), and DCT to single (n = 22). The groups with MFPR had the better pregnancy and perinatal outcomes. Meanwhile, the significantly higher abortion rates but lower live birth and take home baby rates were found in TCT-Expectant group and DCT-Expectant group (all P < 0.05). Besides, the abortion rate of DCT-Expectant group was much higher than TCT-Expectant group (41% verse 15%, P = 0.032). As for the perinatal outcomes, retaining single fetus group showed the advantage of higher birth weight, and elder gestational age in both DCT and TCT pregnancies (all P < 0.05). ConclusionFor DCT and TCT pregnancies, MFPR application could reduce the miscarriage rate, while improving live birth and take home baby rates compared to the expectant groups. Especially, when reduced to a single fetus, MFPR could provide the better perinatal outcomes.

133: Pregnancy outcome after multifetal pregnancy reduction of triplets to twins versus reduction to singleton

Multifetal pregnancy reduction (MPR) of triplets to twins results in improved pregnancy outcome compared with triplet gestations managed expectantly. However, it is not clear whether reduction to singleton may further improve pregnancy outcome. The aim of this study was to determine the rate of pregnancy complications and perinatal outcomes of MPR from triplets to twins versus reduction from triplets to singleton 268 trichorionic and dichorionic triplet pregnancies underwent abdominal MPR at 11-14 weeks' gestation. Cases were divided into two groups according to the final number of embryos: group A, reduction to twins (n=221) and group B, reduction to singleton (n=47). Main outcome measures were rates of pregnancy complications, late abortions, preterm delivery and neonatal outcomes. Non-parametric statistical methods were employed. Triplet pregnancies reduced to twins (group A) delivered earlier (36 vs. 38.6 weeks’ gestation, P<0.001) with lower median birth weight (2172g vs. 2820g, P<0.001) compared with triplets reduced to singleton (group B). The rate of preterm delivery prior to 37 weeks was significantly higher in group A compared with group B (61.2% vs. 21.9%, p<0.001), although twins were not more likely to be delivered prior to 34 weeks (20.1% vs. 14.3%, p=0.52). Regression analysis revealed that after adjustment for age, parity, BMI and gestational age at reduction, triplets reduced to singleton had lower risk for preterm delivery (OR=0.14; 95% CI 0.05-0.39, p<0.001). We did not find a significant difference in the rate of pregnancy loss before 24 weeks’ gestation (6.4% vs. 1.4%, p=0.07) or the rate of intrauterine fetal death after 24 weeks (4.3% vs. 0.9%, p=0.15). There was no significant difference in the prevalence of gestational diabetes, hypertensive diseases of pregnancy and intrauterine growth restriction. Both groups had comparable neonatal outcomes, except for higher rates of NICU admission (29.2% vs. 4.5%, p<0.001), oxygen support (8.2% vs. 0%, p=0.05) and neonatal hypoglycemia (13.2% vs. 0%, p=0.04) in group A. Reduction of triplet pregnancies to singleton is associated with a lower risk of prematurity and superior perinatal outcome compared with reduction to twins. Therefore, the option of reduction to singleton should be considered in cases where the risk of prematurity seems exceptionally high.

Intrafetal laser ablation for embryo reduction from dichorionic triplets to dichorionic twins.

To report the outcome of dichorionic (DC) triplet pregnancies reduced to DC twins by laser ablation of the pelvic vessels of one of the monochorionic (MC) twins. Intrafetal laser embryo reduction (ER) from DC triplets to DC twins was carried out in 61 pregnancies at 11 + 0 to 14 + 3 weeks' gestation. Pregnancy outcome was examined. Intrafetal laser was successfully carried out in all cases, but ultrasound examination within 2 weeks of the procedure demonstrated that the MC cotwin had died in 28 (45.9%) cases and was alive in the other 33 (54.1%). In the DC group, there was one miscarriage at 23 weeks, one neonatal death after delivery at 26 weeks and in the other 31 cases there were two live births at a median gestational age of 35.3 (range, 30.4-38.4) weeks. In the 28 cases in which both MC fetuses died, there was one miscarriage at 16 weeks and in the other 27 cases the separate triplet was liveborn at a median gestation of 38.2 (range, 32.2-42.1) weeks. The overall rate of miscarriage was 3.3% (2/61) and that of preterm birth (PTB) at < 33 weeks was 6.8% (4/59). In the management of DC triplet pregnancies, ER to DC twins by intrafetal laser ablation is associated with lower rates of miscarriage or early PTB, compared with expectant management or ER by fetal intracardiac injection of potassium chloride. However, about half of the pregnancies result in the birth of one rather than two babies. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Selective feticide in complicated monochorionic twin or dichorionic triplet pregnancies applying laser coagulation of umbilical cord vessels

Selective feticide in complicated monochorionic twin or dichorionic triplet pregnancies applying laser coagulation of umbilical cord vessels

Outcome of Multifetal Pregnancy Reduction in Women with a Dichorionic Triamniotic Triplet Pregnancy to a Singleton Pregnancy: A Retrospective Nationwide Cohort Study

Objective: To study the pregnancy outcomes of women with a dichorionic triamniotic triplet pregnancy that was reduced to a singleton pregnancy and to review the literature. Methods: We performed a nationwide retrospective cohort study. We compared time to delivery and perinatal mortality in dichorionic triplet pregnancies reduced to singletons with ongoing dichorionic triplet pregnancies and primary singleton pregnancies. Additionally, we reviewed the literature on the subject. Results: We studied 46 women with a reduced dichorionic triplet pregnancy and 42 women with an ongoing dichorionic triplet pregnancy. Median gestational age at delivery was 38.7 vs. 32.8 weeks, respectively (p < 0.001). Delivery <24 weeks occurred in 9 (19.6%) women with a reduced triplet pregnancy and 4 (9.5%) with an ongoing triplet pregnancy (p = 0.19). Perinatal survival rates between the reduced group and the ongoing triplet group were not significantly different. Conclusion: Multifetal pregnancy reduction in women with a dichorionic triplet pregnancy to a singleton pregnancy prolongs median gestational age at birth. No statistically significant association was found with miscarriage and perinatal survival rates.

Perinatal and obstetric outcomes of dichorionic vs trichorionic triplet pregnancies

Clinical management and outcome of multiple gestation can be affected by chorionicity. In triplet pregnancies, fetal death has been associated with dichorionic (DC) and monochorionic placentation. Studies evaluating triplet pregnancy outcomes in relation to chorionicity have been few and may not reflect contemporary antenatal and neonatal care. The objective of this study was to compare obstetric and perinatal outcomes in DC and trichorionic (TC) triplet pregnancies. We performed a retrospective cohort study of triplet pregnancies that delivered at ≥20 weeks' gestation at 2 Chicago area hospitals from January 1999 through December 2010. Chorionicity was determined by pathology specimen. Maternal and infant charts were reviewed for obstetric and perinatal outcomes. The study population included 159 pregnancies (477 neonates) of which 108 were TC (67.9%) and 51 were DC (32.1%). Over 94% of mothers in this study had all 3 infants survive to discharge regardless of chorionicity. No difference was found in perinatal mortality rate between DC and TC triplets (3.3% vs 4.6%; P= .3). DC triplets were significantly more likely to be very low birthweight (41.8% vs 22.2%; odds ratio, 2.2; 95% confidence interval, 1.2-4.2; P= .02) and to deliver at <30 weeks (25.5% vs 8.3%; odds ratio, 6.1; 95% confidence interval, 1.9-19.4; P=.002) compared to TC triplets. Criteria for twin-twin transfusion syndrome (TTTS) were present in 3 DC triplet pregnancies (5.9%). Neonates in pregnancies complicated by TTTS were less likely to survive 28days as compared to neonates from DC pregnancies that were not affected by TTTS (P= .02) or TC neonates (P= .02) Neonatal survival was similar in DC pregnancies not affected by TTTS and TC pregnancies (98.6% and 96.6%; P= .7). Although perinatal mortality did not correlate with chorionicity, DC pregnancies were more likely to deliver <30 weeks' gestational age and have very low birthweight neonates. Neonatal mortality appears to be mediated by the presence or absence of TTTS as 28-day survival was worse in DC pregnancies complicated by TTTS, but similar between DC pregnancies not affected by TTTS and TC pregnancies.

BJOG Editor's Choice

<scp>BJOG E</scp>ditor's <scp>C</scp>hoice

Dichorionic triplet pregnancies: risk of miscarriage and severe preterm delivery with fetal reduction versus expectant management. Outcomes of a cohort study and systematic review.

In trichorionic pregnancies, fetal reduction from three to two lowers the risk of severe preterm delivery, but provides no advantage in survival. Similar data for dichorionic triamniotic (DCTA) triplets is not readily available. To document the natural history of DCTA triplets and the effect of reduction on the risk of miscarriage and severe preterm delivery, compared with expectant management. Systematic search on MEDLINE, EMBASE, and the Cochrane Library. DCTA triplets with three live fetuses at 8-14 weeks of gestation, outcome data with expectant management and/or reduction, miscarriage before 24 weeks of gestation and/or severe preterm delivery before 32-33 weeks of gestation. Five studies were included. Data from these were combined with data from three centres. There were 331 DCTA triplets. The miscarriage rate was 8.9% (95% CI 5.8-13.3%) and the severe preterm delivery rate was 33.3% (95% CI 27.5-39.7%), with expectant management. The miscarriage rate was 14.5% (95% CI 7.6-26.2%) with a reduction of the monochorionic pair, 8.8% (95% CI 3.0-23.0%) with a reduction of one fetus of the monochorionic pair, and 23.5% (9.6-47.3%) with a reduction of the fetus with a separate placenta. Severe preterm delivery rates were 5.5% (95% CI 1.9-14-9%), 11.8% (95% CI 4.7-26.6%), and 17.6% (95% CI 6.2-41.0%), respectively. In DCTA triplets, expectant management is a reasonable choice when the top priority is a liveborn infant. Where the priority is to minimise severe preterm delivery, the most advisable option is fetal reduction. Further studies are needed to clarify which particular technique is advisable to optimise the outcome.

P18.02: Dichorionic triplet pregnancies: natural history and the effect of embryo reduction

<scp>P</scp>18.02: Dichorionic triplet pregnancies: natural history and the effect of embryo reduction

OP11.08: The influence of chorionicity on miscarriage and fetal loss in triplet pregnancies

The aim of this study was to compare fetal loss rates between trichorionic (TC) triplet pregnancies and those with mixed chorionicity. This was a retrospective cohort study of all triplet pregnancies managed at a single tertiary center over ten year period. Triplet pregnancies which underwent selective reduction were not included in the analysis. Cumulative fetal loss rates for TC and dichorionic (DC) triplet pregnancies from 11 to 36 weeks gestation were analysed using Kaplan-Meier survival curves to assess the difference in mortality between TC and DC twins. Logistic regression analysis was performed to investigate pregnancy and ultrasound characteristics independently associated with the risk of fetal loss. 94 triplet pregnancies (35 trichorionic and 59 mixed chrionicity) were included in the analysis. The total fetal loss rate in TC and in triplet with mixed chorionicity was 3.81% (4/105 fetuses) and 31.0% (55/177), respectively (OR 3.49, 95% CI 1.2 to 10.4). The trend in total fetal loss rate was significantly higher in triplets with mixed chorionicity in all gestation (log rank test, p < 0.0001). The results of the logistic regression analysis showed that mixed chorionicity was independently associated with the occurrence of feta loss in triplets (OR: 1.87, 95% CI 1.5-2.9). The rate of fetal loss remained significantly higher in triplets with mixed chorionicity even afetr exclusion of cases complicated by twin–twin transfusion syndrome (p00.002). Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Trichorionic and Dichorionic Triplet Pregnancies at 10-14 Weeks: Outcome after Embryo Reduction Compared to Expectant Management

Objective: To compare the outcome of trichorionic triplet (TCT) and dichorionic triplet (DCT) pregnancies managed expectantly and those with embryo reduction (ER) at 10-14 weeks to twins or singletons. Methods: This was a retrospective study of triplet pregnancies with 3 live fetuses managed expectantly or by ER. Data were combined with the results of previous studies that used similar entry criteria and outcome measures. The management options were compared for rates of miscarriage and preterm birth <33 weeks. Results: In TCTs managed expectantly (n = 358), the rates of miscarriage and preterm birth were 3.1 and 35.1%. Compared to the expectantly managed TCTs, the rate of miscarriage was higher and preterm birth lower in TCTs with ER to 2 fetuses (n = 833, 7.3 and 13.1%, respectively) and TCTs with ER to 1 fetus (n = 78, 11.5 and 8.7%). In DCTs managed expectantly (n = 136), the rates of miscarriage and preterm birth were 8.8 and 46.0%. In DCTs with ER to 2 fetuses (n = 15) or ER to 1 fetus (n = 42), there was a non-significant increase in miscarriage (13.3 and 16.7%, respectively) and decrease in preterm birth (23.1 and 8%, respectively). Conclusions: In TCT and DCT pregnancies, ER increases the rate of miscarriage but reduces the rate of preterm birth.

Monochorionic Triplets Complicated by Fetofetal Transfusion Syndrome: A Case Series and Review of the Literature

Objective: To compare perinatal outcome in monochorionic (MC) triplets with twin-to-twin transfusion syndrome (TTTS) versus dichorionic (DC) triplets with TTTS. Study Design: Retrospective analysis of all triplets with TTTS treated at our center and all cases reported in the literature between 1990 and 2010. Survival and gestational age at birth of MC and DC triplets were compared and stratified by type of intervention. We excluded triplets with one or more fetal deaths <16 weeks’ gestation and those with one or more fetuses with congenital anomalies. Results: MC triplets were affected by TTTS in a total of 27 cases, and overall survival was 51% (38/75 fetuses) compared to 105 DC triplets with a survival of 76% (220/291 fetuses) (p < 0.05). Mean gestational age at birth in MC triplets was 28 weeks, compared to 31 weeks in DC triplets (p < 0.05). Perinatal survival of at least one fetus in MC triplet and DC triplet pregnancies was 70% (19/27) and 91% (96/105) (p < 0.05). In DC triplets, survival after laser therapy was significantly improved compared to expectant management, amniodrainage or selective feticide (p < 0.05). Conclusion: MC triplets with TTTS are at a considerably higher risk for perinatal mortality and preterm birth than DC triplets. The optimal strategy to manage MC triplets with TTTS, including the role of selective feticide and laser therapy of all anastomoses, is still to be established.

Trizygotic dichorionic triplets with 46,XX/46,XY chimerism in both fetuses of the monochorionic pair

Monochorionic fetuses are traditionally thought of as monozygotic (MZ), arising from a single embryo that splits during early embryogenesis. With rare exception, they typically exhibit the same genotype and the same gender. However, several recent reports have documented that monochorionicity does not always indicate monozygosity (Souter et al., 2003). At least 14 such cases have been reported (Ekelund et al., 2008). We report a trizygotic triplet pregnancy conceived by in vitro fertilization (IVF) in which triamniotic dichorionic placentation was identified in addition to hematopoietic chimerism in the monochorionic pair. A 29-year-old Caucasian, insulin-dependent diabetic woman gravida 2, para 1, conceived a triplet gestation with the assistance of IVF. Three embryos were transferred. An ultrasound performed at 7 weeks revealed three viable embryos in three gestational sacs. A thin membrane, with a direct, perpendicular insertion into a single placenta, was visualized between sacs B and C. There was no evidence of a lambda sign at the placental insertion site. These findings indicated monochorionicity between the B and C sacs. Fetus A was surrounded by a single amnion and a single chorion. The sonographic findings indicated a triamniotic, dichorionic triplet pregnancy. Genotypes of the B and C embryos were assumed to be identical due to the observed monochorionicity. At 12 weeks and 5 days, the ultrasound findings were confirmed. As part of a Down syndrome risk assessment, nuchal translucency measurements were 1.9, 1.3 and 2.2 mm, for triplets A, B and C, respectively. Ultrasound at 18 weeks revealed a gender discrepancy between the monochorionic fetuses, with triplet B demonstrating normal appearing female external genitalia and triplet C demonstrating normal appearing male external genitalia. Fetus A was noted to be female. Due to the gender discrepancy, amniocentesis was performed on all three gestational sacs. Separate needle insertions were performed for each fetus. Following withdrawal

Zygosity and Chorionicity in the Prognosis of Triplet Pregnancies: Contribution of Microsatellites

We assess the prognostic values of zygosity and chorionicity in triplet pregnancies (TP) with the assistance of microsatellites analysis. 53 consecutive TP whose prenatal care and delivery occurred in our maternity hospital were included in this prospective study. Zygosity of all sets of triplets (alive or stillbirth, after 22 weeks of gestation) was determined by PCR-amplified microsatellites markers analysis. Chorionicity was determined by placental analysis in our fetopathology referral department and validated by molecular analysis of zygosity. Placental conformations, obstetrical and neonatal outcomes of TP were studied according to their zygosity and chorionicity. Monozygotic and to a greater extent, dizygotic TP were associated with an increase in placental ischemic injuries, velamentous cord insertions, twin-twin transfusion syndromes, fetal anomalies, and perinatal mortality when compared with the trizygotic TP (p < 0.05). Monochorionic and more significantly, dichorionic TP presented with the same increases as trichorionic TP (p < 0.05). Thus chorionicity easily determined by ultrasound evaluation during the first trimester of the pregnancy must remain the main prognosis criterion in TP. Taking into account the rare indications of prenatal diagnosis of zygosity, it became apparent that chorionicity has a greater impact than zygosity when distinguishing high-risk groups of TP.

Zygosity and chorionicity in triplet pregnancies: new data

In studies of twin and triplet pregnancies, molecular genetic techniques have rarely been used to confirm zygosity yet this is the most accurate approach. The aim of this study was to present the cross-distribution of chorionicity and zygosity in triplet pregnancies as a function of their mode of conception using such techniques. Rates of monozygosity were studied simultaneously. Forty-nine consecutive sets of triplets were observed in the study, including 18 sets of spontaneously conceived (SC) triplet pregnancies and 31 sets resulting from assisted reproduction technologies (ARTs). Zygosity was determined through PCR-amplified microsatellite analysis. Chorionicity was determined by placental analysis in our department of fetopathology. Sets of triplets were considered as twin pairs in order to determine the rate of monozygosity. For SC triplet pregnancies, the rate of monozygotic (MZ) twin pairs was 48%; 30% of dichorionic (DC) triplet pregnancies were MZ and 70% dizygotic (DZ); 20% of trichorionic (TC) triplet pregnancies were DZ and 80% trizygotic (TZ). For triplet pregnancies conceived using ART, the rate of MZ twin pairs was 6.5%; 100% of DC triplet pregnancies were DZ; 4% of TC triplet pregnancies were DZ and 96% TZ. This study is the first report to present the cross-distribution of chorionicity and zygosity in triplet pregnancies as a function of their mode of conception. In triplet pregnancies conceived using ART, DC triplets are always DZ, and TC triplets are almost always TZ.

Live-birth deliveries of dichorionic triplet pregnancy – a case report

Live-birth deliveries of dichorionic triplet pregnancy – a case report