Trichorionic Triplet Research Articles

Triplet pregnancy: is the mode of conception related to perinatal outcomes?

Many triplets are conceived as a consequence of assisted reproductive technology (ART). Concerns have been raised that triplet pregnancies conceived by ART are more complicated than those conceived spontaneously. The purpose of this study was to evaluate all triplet pregnancies managed over a 12-year period to determine if there were any differences in outcome based on the mode of conception. All triplet pregnancies between 1999 and 2011 that reached at least 20 weeks' gestation and that were managed at the Royal Women's Hospital (RWH), Melbourne, Victoria were identified. Maternal and neonatal outcomes were compared between ART conceived and spontaneously conceived triplets. In the study period, 53 sets of triplets managed in our institution met the eligibility criteria. Twenty-five triplet sets were conceived by ART and 28 were conceived spontaneously. More ART conceptions resulted in trichorionic triamniotic (TCTA) triplets than did spontaneous conceptions (p = .015). There were no differences between ART and spontaneously conceived triplets for any of the maternal or neonatal complications studied. Trichorionic (TC) triplets delivered at a later gestation than other triplets: 32.1 (SD 2.9) versus 30.4 (SD 3.9) weeks (p = .08). TC triplets were significantly less likely to die than monochorionic (MC) or dichorionic (DC) triplets: 3/93 (3%) versus 13/66 (20%) (p = .025). In conclusion, triplets conceived by ART are more likely to have TCTA placentation and TCTA triplet sets had lower mortality rates than other triplet combinations. Outcomes for triplets conceived by ART were similar to those of triplets conceived spontaneously.

Demographic and Assisted Reproduction Related Factors Associated with Dichorionic Triplet Gestations

Our objective was to evaluate which demographic factors or assisted reproductive technologies were associated with IVF triplet gestations where one of the embryos split, resulting in a dichorionic triplet gestation. This was a case-control study of dichorionic versus trichorionic triplet gestations that underwent assisted reproductive technology over the last 5 years at our fertility center. There were 53 cases of dichorionic triamniotic triplet gestations compared to 119 trichorionic triplet controls. There were no significant demographic differences between the cases and controls. 51/53 dichorionic triplets and 86/119 trichorionic triplets were conceived through IVF, the remaining utilized intrauterine insemination. ICSI was performed in virtually all patients that underwent IVF. Of the potential risk factors studied, hatching was used in 70.6% of dichorionic compared to 89.5% of trichorionic IVF triplets (p = 0.005); embryo transfer was performed on Day 5 or 6 compared to Day 3 in 88.0% dichorionic vs 71.8% trichorionic (p = 0.028). Frozen sperm was utilized more frequently with dichorionic than with trichorionic triplets, 26.0% vs 10.9% (p < 0.011). Only 4 (7.5%) of the IVF cases underwent pre-implantation genetics. Certain assisted reproductive technologies appear to be associated with embryo splitting and a dichorionic triplet gestation. More research is needed in this area to further elucidate these findings.

Pregnancy outcome of early multifetal pregnancy reduction: triplets to twins versus triplets to singletons

Multifetal pregnancy reduction (MPR) of triplets to twins results in improved pregnancy outcomes compared with triplet gestations managed expectantly. Perinatal outcomes of early transvaginal MPR from triplets to twins were compared with reduction from triplets to singletons. Seventy-four trichorionic triplet pregnancies that underwent early transvaginal MPR at 6–8 weeks gestation were included. Cases were divided into two groups according to the initial procedure: reduction to twin (n = 55) or to singleton (n = 19) gestations. Infants from triplet pregnancies reduced to twins were delivered earlier (36.6 versus 37.9 weeks; P = 0.04) and had lower mean birth weights (2364 g versus 2748 g; P = 0.02) compared with those from triplets reduced to singleton gestations. The rates of pregnancy loss before 24 weeks (3.6% versus 5.3%), as well as of preterm delivery before 32 and 34 weeks of gestation (0% versus 5.3% and 7.3% versus 5.3%, respectively) were similar between the twin and singleton pregnancies. No significant difference was found in the prevalence of gestational diabetes (15.1% versus 5.6%) or gestational hypertension (24.5% versus 16.7%) between the groups. Selective reduction of triplet pregnancies to singleton rather than twin gestations is associated with improved outcomes.

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.

The effectiveness of multifetal pregnancy reduction in trichorionic triplet gestation

The objective of the study was to assess in trichorionic triplet pregnancies the effectiveness of elective reduction to twins. This was a nationwide retrospective cohort study. We compared the time to delivery and perinatal mortality in trichorionic triplet pregnancies electively reduced to twins with ongoing trichorionic triplets and primary dichorionic twins. We identified 86 women with reduced trichorionic triplet pregnancies, 44 with ongoing trichorionic triplets, and 824 with primary twins. Reduced triplets had a median gestational age at delivery of 36.1 weeks (interquartile range [IQR], 33.3-37.5 weeks) vs 33.3 (IQR, 28.1-35.2) weeks for ongoing triplets and 37.1 (IQR, 35.3-38.1) weeks for primary twins (P < .001). The total number of surviving children in the reduced group was 155 (90%) vs 114 (86%) in the ongoing triplet group. After reduction, 75 of women (87%) had all their fetuses surviving, compared with 36 (82%) (relative risk [RR], 1.3; 95% confidence interval [CI], 0.72-2.3) for ongoing triplets and 770 (93%) (RR, 0.91; 95% CI, 0.82-1) for primary twins. There were 6 women without any surviving children (7%) after reduction vs 5 (11.4%) (RR, 0.81; 95% CI, 0.47-1.4) among women with ongoing triplets and 32 (3.9%) (RR, 1.7; 95% CI, 0.8-3.7) in women with primary twins. In women with a triplet pregnancy, fetal reduction increases gestational age at birth with 3 weeks as compared with ongoing triplets. However, there the impact on neonatal survival is limited.

A comparative study of obstetric outcomes in electively or spontaneously reduced triplet pregnancies

This study aimed at evaluating the pregnancy outcomes of IVF triplets which are spontaneously or electively reduced to twins and to compare them with non-reduced triplets and twins. Retrospective analysis of trichorionic triplets and dichorionic twins of IVF pregnancies. Preeclampsia rate was significantly higher in triplet group (p = 0.014). Premature contractions requiring tocolysis were seen more often in spontaneous reduction and triplet groups compared to elective reduction and twin groups (p < 0.001). Elective reduction and twin groups had significantly lower rate of infants weighing less than 1,500 g than those of triplets (p < 0.001). Highest rate for infants weighing over 2,500 g was found in primary twin group. Preterm delivery rates were significantly lower in both twin and elective reduction groups compared to triplet and spontaneous reduction groups (p < 0.001). Proportion of women giving birth at term was not different in elective reduction and twin groups, and they were significantly higher compared to spontaneous reduction group (p = 0.024). Perinatal mortality rates of both elective reduction and twin groups were significantly less than those in the triplet group (p = 0.045 and p < 0.001, respectively). Obstetric outcomes of triplets from IVF or ovulation induction cycles undergoing elective reduction are better than ongoing triplet and spontaneous reduction groups and are similar to that of dichorionic twins.

Selective Fetal Reduction in Triplet Pregnancy: Indian Experience — A Retrospective Review of 32 Cases

ABSTRACT Aim To review the effects of selective fetal reduction in trichorionic triplet pregnancy with focus on risk of miscarriage and preterm delivery in Indian women and thus provide local data for counseling the prospective parents in similar situation. Materials and methods This retrospective study reviewed the pregnancy outcome of 32 sets of triplet pregnancies following fetal reduction. All mothers had trichorionic triplet pregnancy with three live fetuses at 10 to 11 weeks of gestation. One to two milliliter ml of 10% potassium chloride (KCl) was injected into the heart of the target fetus to achieve asystole. Results The miscarriage (pregnancy loss before 24 completed weeks) rate in our study was 3.12%. The delivery in our study at. 32 and. 35 weeks were 6.45 and 51.61% respectively. The mean gestational age (mean ± SD) of the mothers was 242.58 ± 12.93 days. Regarding the birthweight of neonates, 5.08% babies were &lt;1500 gm, 89.83% were between 1500 and. 2500 gm and 5.08% were &gt; 2500 gm. The mean birth weight (mean ± SD) of the babies was 1921.18 ± 339.78 gm. There was no neonatal death in this cohort. Conclusion Our study results, when compared with ‘expectant management’ group of two European studies as there was no control in our study, appeared significantly better in terms of gestational age at delivery and neonatal birth weight. Selective fetal reduction remains an effective option to Indian women with trichorionic triplet pregnancy. How to cite this article Chaudhury K, Mukherjee K. Selective Fetal Reduction in Triplet Pregnancy: Indian Experience — A Retrospective Review of 32 Cases. J South Asian Feder Obst Gynae 2014;6(3):144-150.

Evolutionary genetics and implications of small size and twinning in callitrichine primates.

New World monkeys (NWMs) are characterized by an extensive size range, with clawed NWMs (subfamily Callitrichinae, or callitrichines) such as the common marmoset manifesting diminutive size and unique reproductive adaptations. Perhaps the most notable of these adaptations is their propensity toward multiple gestations (i.e., dichorionic twins and trichorionic triplets). Indeed, with the exception of Goeldi's monkey (Callimico), callitrichine singleton pregnancies rarely occur. Multiple gestations seem to have coevolved with a suite of reproductive adaptations, including hematopoetic chimerism of siblings, suppression of reproduction in nondominant females, and cooperative alloparenting. The sequencing of the common marmoset (Callithrix jacchus) genome offers the opportunity to explore the genetic basis of these unusual traits within this primate lineage. In this study, we hypothesized that genetic changes arising during callitrichine evolution resulted in multiple ovulated ova with each cycle, and that these changes triggered adaptations that minimized complications common to multiple gestations in other primates, including humans. Callitrichine-specific nonsynonymous substitutions were identified in GDF9, BMP15, BMP4, and WFIKKN1. WFIKKN1, a multidomain protease inhibitor that binds growth factors and bone morphogenetic proteins, has nonsynonymous changes found exclusively in common marmosets and other tested callitrichine species that twin. In the one callitrichine species that does not produce twins (Callimico), this change has reverted back to the ancestral (nontwinning) primate sequence. Polymorphisms in GDF9 occur among human cohorts with a propensity for dizygotic twins, and polymorphisms in GDF9 and BMP15 are associated with twinning in sheep. We postulate that positive selection affected NWM growth patterns, with callitrichine miniaturization coevolving with a series of reproductive adaptations.

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.

Clinical features and short-term outcomes of triplet pregnancies in Japan

ObjectiveTo review clinical features and short-term outcomes of triplet pregnancies among Japanese women. MethodsA retrospective analysis was carried out among 320 Japanese women with triplet pregnancies (8 monochorionic, 75 dichorionic, and 150 trichorionic triplets; 87 with unknown placental chorionicity) who delivered at 22 gestational weeks or more between January 2005 and December 2008. ResultsDelivery was by cesarean for 315 (98%) women. Gestational age at delivery was 32.3±2.8weeks (mean±SD) and 33.2weeks (median), and 97%, 61%, and 14% of women delivered at less than 37, less than 34, and less than 30 gestational weeks, respectively. For live-born infants, mean birth weight was 1762±437g, 1608±396g, and 1406±380g for the heaviest, middle, and lightest triplet, respectively. Eighteen (5.6%) women experienced perinatal mortality (3 triplets for 1 woman, 2 triplets for 4 women, and 1 triplet for 13 women). Perinatal mortality was 25 deaths per 1000 deliveries, and decreased with increasing number of chorionic membranes (125, 44, and 20 per 1000 mono-, di-, and trichorionic triplet deliveries, respectively). ConclusionShort-term outcomes were good among triplet pregnancies in Japan. The data may be useful for counseling Japanese women with triplet pregnancies.

Retain singleton or twins? Multifetal pregnancy reduction strategies in triplet pregnancies with monochorionic twins

To assess the effectiveness and feasibility of retaining a singleton or twins for multifetal pregnancy reduction (MFPR) in triplet pregnancy with monochorionic twins. This retrospective study was conducted from January 2006 to September 2011 at a university reproductive medical center. Multifetal pregnant patients (n=35) with dichorionic triplets underwent MFPR in the first trimester to reduce one or both monochorionic twins. These cases were divided into two groups: Group A (9 MFPR cases to reduce one monochorionic twin) and Group B (26 MFPR for both monochorionic twins). Control A (for Group A) included another 18 cases of trichorionic triplet reduction to twins; Control B (for Group B) included 35 cases of trichorionic triplet reduction to singletons. MFPR was performed during the same period for all groups. Pregnancy outcomes were compared between groups. Patients were 28-39 years old; the average gestation for fetal reduction was 6-8 weeks. The early abortion rate was lower in Group A than Group B (0 versus 11.5%, p=0.339), but the late abortion rate was significantly higher in Group A. (33.3% versus 0, p=0.000). Groups A and B did not differ significantly in premature labor rate, term birth rate, gestation at delivery and take-home baby rate. The rate of very low and low birth weight was significantly higher in Group A than Group B (50% versus 0, p=0.001), and the average birth weight was significantly lower in Group A (2391.7±318.5 versus 3119.6±523.9, p=0.001). Group A had significantly more low birth-weight newborns than Control A (50% versus 13.3%, p<0.05 [0.024]). Group B (retained singleton) had similar pregnancy outcomes and neonatal conditions as Control B. Retaining a singleton is always the best choice when deciding about using MFPR to improve pregnancy outcomes. For patients having a triplet pregnancy with monochorionic twins and strongly desiring to keep twins, MFPR in one monochorionic twin was feasible by aspirating embryonic parts early in gestation (6-8 weeks) with no drug injection. Pregnancy outcomes are similar with twin reduction in trichorionic triplet pregnancy.

Fetal reduction of triplet pregnancy: one or two?

To review outcomes following reductions in trichorionic triplet pregnancies at our institution. Retrospective analysis of the outcome of trichorionic triamniotic triplets reduced to singletons (group I, n = 44) or twins (group II, n = 136) at 10 and 12 weeks of gestation. Reduction to one or two was based on parent's preference, hence unrelated to any specific obstetrical or maternal issue. Early fetal loss rate (e.g. <24 weeks) was 9.1% in group I versus 5.1% in group II (p = 0.83). In group I, the take-home baby rate was 86.4% versus 91.9% in group II (p = 0.8). In group I, 17.5% of the women gave birth between 33 and 36(+6) weeks of gestation versus 40.6% in group II (p = 0.026). Delivery beyond 37 weeks was 72.5% in group I and 46.9% in group II (p = 0.01). Intrauterine growth restriction rate was 27.0% in group I versus 45.0% in group II (p = 0.049). Reduction to one rather than two fetuses led to significantly higher term delivery rate without significant differences in fetal loss rate or take-home baby rate.

Obstetric outcomes of IVF trichorionic triamniotic triplets which are spontaneously or electively reduced to twins

To assess the obstetric outcome of IVF triplets which are spontaneously or electively reduced to twins. Retrospective study of trichorionic triplets (TT) and dichorionic twins (DT) conceived with IVF. Compared to TT without reduction, TT with spontaneous reduction (SR) (OR: 5.6, 95% CI: 1.6-19.9) or elective reduction (ER) (OR: 14.0, 95% CI: 3.92-50.02) to twins were significantly more likely to be delivered at ≥34 weeks. Compared to DT likelihood of delivery ≥34 weeks was similar for SR and ER. Compared to TT without reduction, the risk of pregnancy loss before 24 weeks was not increased with SR or ER. Compared to DT the risk of pregnancy loss before 24 weeks was not significantly increased for SR or ER. Obstetric outcome of IVF triplets with SR is better than ongoing triplets and is similar to that of ER of TT and DT.

Ultrasound assessment of the prognosis in triplet pregnancies

To assess the diagnostic accuracy and show the prognostic influence of different ultrasonographic criteria in triplet pregnancies(TP). Retrospective study. Tertiary care center in France. Fifty-one consecutive TP in which at least one of the children, live- or stillborn, weighed 500 g or more, and with a gestation period of at least 22 weeks. Chorionicity, abnormal umbilical artery Doppler waveforms, intrauterine weight (IUW) <10th centile and prenatal diagnosis of fetal anomaly were studied simultaneously as prognostic criteria. Chorionicity was confirmed at birth by placental pathology. Diagnosis of chorionicity/amnionicity and IUW <10th centile. Neonatal intensive care unit admission, occurrence of respiratory distress syndrome and perinatal mortality. Prenatal misclassification of chorionicity/amnionicity after postnatal perinatal pathology review was 12%. The positive predictive value of IUW <10th centile diagnosis was 44% for the prediction of birthweight <10th centile. Prenatal diagnosis of mono- or dichorionic placentation was associated with increased neonatal morbidity in comparison with that of trichorionic triplets. Perinatal mortality was significantly increased where mono- or dichorionic placentation was diagnosed prenatally (OR: 4.2; CI: 1.04-17), IUW <10th centile (OR: 10; CI: 2.4-41), with raised odds for abnormal umbilical Doppler measurements (OR: 9.7; CI: 2-47) and fetal anomaly (OR: 6.4; CI: 1.4-28.9). Early prenatal diagnosis of chorionicity is of major importance in triplet pregnancy. Experienced sonographers must quickly evaluate any uncertain diagnosis. In cases of unknown chorionicity, other ultrasonographic criteria can highlight high-risk triplet pregnancy, but at a later stage.

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.

Intrauterine growth in multiple pregnancies in relation to fetal number, chorionicity and gestational age

To examine birth weight in dichorionic and monochorionic twins and trichorionic triplets, and to estimate the relative independent importance on growth of fetal number, chorionicity and gestational age. Four groups of pregnancies were examined: 12,816 singleton pregnancies, 302 monochorionic twin pregnancies, 569 dichorionic twin pregnancies, and 97 trichorionic triplet pregnancies. Chorionicity was determined at 10-14 weeks on the basis of the presence or absence of the lambda sign in twins, and by examining the ipsilon zone in triplets. The relationship between birth weight and gestational age in singletons was established, and using this equation the expected mean birth weights for all gestational ages were calculated. For each case in all groups, the difference between the observed birth weight for each fetus and the appropriate normal mean for gestation in singletons was calculated (Z-score). Multiple regression analysis was used to examine the independent contribution of gestational age, number of fetuses and chorionicity in the prediction of actual birth weight and birth weight Z-score. Birth weight Z-score was significantly lower than the expected mean in singletons for dichorionic twins, monochorionic twins and trichorionic triplets (t = 15.4, P < 0.0001, t = 21.7, P < 0.0001 and t = 19.9, P < 0.0001, respectively). Furthermore, the reduction in expected birth weight was significantly greater for monochorionic twins and trichorionic triplets compared with dichorionic twins (t = 6.3, P < 0.0001 and t = 7.8, P < 0.0001, respectively). Multiple regression analysis demonstrated that number of fetuses, presence of a monochorionic placenta and gestational age were independently associated with birth weight Z-score, the strongest effect being fetal number, followed by monochorionicity (t = - 23.4, P < 0.0001, t = - 8.3, P < 0.0001 and t = - 4.9, P < 0.0001, respectively). The finding that monochorionic twins were of lower adjusted birth weight than dichorionic twins, and the significant independent effect of chorionicity on birth weight suggest that monochorionic placentation in itself has an effect on intrauterine growth. The effect of fetal number independent of chorionicity is demonstrated by the lower birth weight of trichorionic triplets compared with dichorionic twins.

Risks of miscarriage and early preterm birth in trichorionic triplet pregnancies with embryo reduction versus expectant management: new data and systematic review

Risks of miscarriage and early preterm birth in trichorionic triplet pregnancies with embryo reduction versus expectant management: new data and systematic review

Placental volume in twin and triplet pregnancies measured by three‐dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation

To compare the placental volume at 11 + 0 to 13 + 6 weeks' gestation between singleton and multiple pregnancies and to examine the possible effect of chorionicity on placental volume. The placental volume was measured by three-dimensional (3D) ultrasound using the Virtual Organ Computer-aided AnaLysis (VOCAL) technique in 290 consecutive twin and 37 triplet pregnancies at 11 + 0 to 13 + 6 weeks of gestation. For the comparison of twin, triplet and singleton placental volumes each measurement was expressed as a multiple of the median (MoM) for singletons, previously established from the study of 417 normal fetuses at 11 + 0 to 13 + 6 weeks of gestation. Median twin and triplet placental volumes were 1.66 and 2.28 MoM for singletons, respectively. In twins the placental volumes increased significantly with gestation from a median of 83.6 mL (5th and 95th centiles: 56.0 mL and 124.9 mL) at 11 + 0 weeks to 149.3 mL (5th and 95th centiles: 100.0 mL and 223.1 mL) at 13 + 6 weeks. The median MoM in monochorionic twins was not significantly different from that in dichorionic twins with fused placentas or dichorionic twins with separate placentas. In triplets the placental volumes increased significantly with gestation from a median of 114.9 mL (5th and 95th centiles: 77.6 mL and 170.1 mL) at 11 weeks to 217.9 mL (5th and 95th centiles: 147.2 mL and 322.5 mL) at 13 + 6 weeks. There were no significant differences in total placental volume between monochorionic and dichorionic triplets, monochorionic and trichorionic triplets, or dichorionic and trichorionic triplets. Placental volume in multiple pregnancies does not depend on chorionicity, and the rate of placental growth between 11 and 13 + 6 weeks is not significantly different between singletons, twins and triplets. Moreover, for a given gestational age the placental volume corresponding to each fetus in twins and triplets is 83% and 76%, respectively, of the placental volume in singletons.

Risks of miscarriage and early preterm birth in trichorionic triplet pregnancies with embryo reduction versus expectant management: new data and systematic review

Triplet pregnancies are associated with a high risk of miscarriage and early preterm birth. It is uncertain if the outcome is improved by embryo reduction (ER). We examined trichorionic triplet pregnancies with three live fetuses at 10-14 weeks of gestation that were managed expectantly or by ER. The two groups were compared for the rates of miscarriage, defined as pregnancy loss before 24 weeks, and preterm delivery prior to 32 weeks. In addition, systematic searches were performed to identify studies comparing outcomes in expectant management versus ER in triplet pregnancies. We combined data from 365 pregnancies managed in our centre with those of five previous studies. In total there were 893 pregnancies. In the ER group (n=482) compared to the expectantly managed group (n=411), the rate of miscarriage was higher [8.1 versus 4.4%; relative risk (RR)=1.83, 95% confidence interval (CI)=1.08-3.16, P=0.036] and the rate of early preterm delivery was lower (10.4 versus 26.7%, RR=0.37, 95% CI=0.27-0.51, P<0.0001). It was calculated that seven (95% CI=5-9) reductions needed to be performed to prevent one early preterm delivery, while the number of reductions that would cause one miscarriage was 26 (95% CI=14-193). In trichorionic triplets, ER to twins is associated with an increase in the risk of subsequent miscarriage and decrease in risk of early preterm birth.

Comparative study of perinatal outcome of dichorionic and trichorionic iatrogenic triplets

The purpose of this study was to compare the perinatal outcome of dichorionic and trichorionic triplets who were conceived by assisted reproductive techniques. In this retrospective study, the maternal, neonatal, and chorionicity data were collected from 106 sets of trichorionic triamniotic and 34 sets of dichorionic triamniotic triplet pregnancies who were conceived by assisted reproductive techniques between January 1986 and December 2000. Perinatal and neonatal data were evaluated in relation to chorionicity and intertriplet birth weight discordance. The dichorionic triamniotic triplets have an 8-fold higher risk of perinatal death than trichorionic triamniotic gestations (odds ratio, 7.9; 95% CI, 4.4-14.0; P < .001). This is attributed to a higher risk of very low birth weight (P < .01), delivery at < 30 weeks of gestation (P < .001), and premature rupture of membrane (P < .001) in dichorionic triamniotic triplets compared with trichorionic triamniotic pregnancies. Twin-twin transfusion syndrome (odds ratio, 11.5; 95% CI, 4.8-27.7; P < .001), delivery at < 30 weeks of gestation (odds ratio, 40.5; 95% CI, 16.9-97; P < .01), premature rupture of membrane (odds ratio, 6.7; 95% CI, 3.8-11.9; P < .01), and nulliparity (odds ratio, 3.1; 95% CI, 1.6-6.1; P < .05) had independent effects on perinatal loss rate. The dichorionic triplets have an 8 times higher perinatal mortality rate than trichorionic triamniotic pregnancies.