Adverse perinatal outcome of twin pregnancies according to chorionicity: review of the literature

Pregnancy and obstetric outcomes of dichorionic triamniotic triplet pregnancies with selective foetal reduction after assisted reproductive technology

BACKGROUND

It is generally beneficial and recommended that dichorionic triamniotic (DCTA) triplet pregnancies be reduced to monochorionic (MC) twin or singleton pregnancies after assisted reproductive technology (ART). However, some infertile couples still have a firm desire to retain twins. For this reason, the best foetal reduction strategies need to be available for infertile couples and clinicians. Given that data on the elective reduction of DCTA triplet pregnancies to twin pregnancies are scarce, we investigated the outcomes of elective reduction of DCTA triplet pregnancies through the retrospective analysis of previous data.

METHOD

Patients with DCTA triplet pregnancies who underwent elective foetal reduction between January 2012 and June 2020 were recruited. A total of 67 eligible patients with DCTA triplet pregnancies were divided into two groups: a DCTA-to-dichorionic diamniotic (DCDA) twin group (n = 38) and a DCTA-to-monochorionic diamniotic (MCDA) twin group (n = 29); the basic clinical data of the two groups were collected for comparison.

RESULTS

Compared with the DCDA-to-MCDA twin group, the DCTA-to-DCDA twin group had lower rates of complete miscarriage (7.89% versus 31.03%, p = 0.014), early complete miscarriage (5.26% versus 24.14%, p = 0.034), late preterm birth (25.71% versus 65.00%, p = 0.009) and very low birth weight (0 versus 11.11%, p = 0.025). In addition, the DCTA-to-DCDA twin group had higher rates of full-term delivery (65.71% versus 25.00%, p = 0.005), survival (92.11% versus 68.97%, p = 0.023), and taking the babies home (92.11% versus 68.97%, p = 0.023) than did the DCTA-to-MCDA twin group. In terms of neonatal outcomes, a significantly greater gestational age (38.06 ± 2.39 versus 36.28 ± 2.30, p = 0.009), average birth weight (3020.77 ± 497.33 versus 2401.39 ± 570.48, p < 0.001), weight of twins (2746.47 ± 339.64 versus 2251.56 ± 391.26, p < 0.001), weight of the larger neonate (2832.94 ± 320.58 versus 2376.25 ± 349.95, p < 0.001) and weight of the smaller neonate (2660.00 ± 345.34 versus 2126.88 ± 400.93, p < 0.001) was observed in the DCTA-to-DCDA twin group compared to the DCTA-to-MCDA twin group.

CONCLUSION

The DCTA-to-DCDA twin group had better pregnancy and neonatal outcomes than the DCTA-to-MCDA twin group. This reduction approach may be beneficial for patients with dichorionic triamniotic triplet pregnancies who have a strong desire to have DCDA twins.

Prevalence and adverse outcomes of twin pregnancy in Eastern Africa: a systematic review and meta-analysis

INTRODUCTION

Multiple pregnancies are much more common today than they were in the past. Twin pregnancies occur in about 4% of pregnancies in Africa. Adverse pregnancy outcome was more common in twin pregnancy than in singleton pregnancy. There is no pooled evidence on the burden and adverse pregnancy outcome of twin pregnancy in eastern Africa. Thus, this systematic review and meta-analysis were conducted to assess the prevalence and adverse pregnancy outcomes of twin pregnancies.

METHODS

This systematic review and meta-analysis covers published and unpublished studies searched from different databases (PubMed, CINAHL (EBSCO), EMBASE, DOAJ, Web of Sciences, MEDLINE, Cochrane Library, SCOPUS, Google Scholar, and Google search). Finally, 34 studies were included in this systematic review and meta-analysis. JBI checklist was used to assess the quality of included papers. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Data synthesis and statistical analysis were conducted using STATA Version 14 software. Heterogeneity and publication bias were assessed. A forest plot was used to present the pooled prevalence using the random effect model.

RESULTS

The prevalence of twin pregnancy in eastern Africa was 3% [95% CI: 2, 3]. The adverse pregnancy outcomes like neonatal intensive care unit admission (78%), low birth weight (44%), low APGAR score (33%), prematurity (32%), stillbirth (30%), neonatal mortality (12%) and maternal complications like hypertensive disorder of pregnancy (25%), postpartum hemorrhage (7%), Cesarean section (37%), premature rupture of membrane (12%) and maternal mortality are more common among twin pregnancy than singleton pregnancy.

CONCLUSION

One in every 33 children born a twin in east Africa; admission to neonatal intensive care unit, low birth weight, low APGAR score, prematurity, stillbirth, neonatal mortality and maternal complications are its associated adverse birth outcomes. Since twin pregnancy is a high-risk pregnancy, special care is needed during pregnancy, labor and delivery to reduce adverse pregnancy outcomes.

Nutritional Intake in Dichorionic Twin Pregnancies: A Descriptive Analysis of a Multisite United States Cohort

INTRODUCTION

Twin gestations have greater nutritional demands than singleton gestations, yet dietary intakes of women with twin gestations have not been well described.

METHODS

In a prospective, multi-site US study of 148 women with dichorionic twin gestations (2012-2013), we examined longitudinal changes in diet across pregnancy. Women completed a food frequency questionnaire during each trimester of pregnancy. We examined changes in means of total energy and energy-adjusted dietary components using linear mixed effects models.

RESULTS

Mean energy intake (95% CI) across the three trimesters was 2010 kcal/day (1846, 2175), 2177 kcal/day (2005, 2349), 2253 kcal/day (2056, 2450), respectively (P = 0.01), whereas the Healthy Eating Index-2010 was 63.9 (62.1, 65.6), 64.5 (62.6, 66.3), 63.2 (61.1, 65.3), respectively (P = 0.53).

DISCUSSION

Women with twin gestations moderately increased total energy as pregnancy progressed, though dietary composition and quality remained unchanged. These findings highlight aspects of nutritional intake that may need to be improved among women carrying twins.

Interpregnancy interval and adverse birth outcomes: a population-based cohort study of twins

BACKGROUND

To investigate associations between interpregnancy intervals (IPIs) and adverse birth outcomes in twin pregnancies.

METHODS

This retrospective cohort study of 9,867 twin pregnancies in Western Australia from 1980-2015. Relative Risks (RRs) were estimated for the interval prior to the pregnancy (IPI) as the exposure and after the pregnancy as a negative control exposure for preterm birth (< 37 weeks), early preterm birth (< 34 weeks), small for gestational age (SGA: < 10th percentile of birth weight by sex and gestational age) and low birth weight (LBW: birthweight < 2,500 g).

RESULTS

Relative to IPIs of 18-23 months, IPIs of < 6 months were associated with a higher risk of early preterm birth (aRR 1.41, 95% CI 1.08-1.83) and LBW for at least one twin (aRR 1.16, 95% CI 1.06-1.28). IPIs of 6-11 months were associated with a higher risk of SGA (aRR 1.24, 95% CI 1.01-1.54) and LBW for at least one twin (aRR 1.09, 95% CI 1.01-1.19). IPIs of 60-119 months and ≥ 120 months were associated with an increased risk of preterm birth (RR 1.12, 95% CI 1.03-1.22; and (aRR 1.25, 95% CI 1.10-1.41, respectively), and LBW for at least one twin (aRR 1.17, 95% CI 1.08-1.28; and aRR 1.20, 95% CI 1.05-1.36, respectively). IPIs of ≥ 120 months were also associated with an increased risk of early preterm birth (aRR 1.42, 95% CI 1.01-2.00). After negative control analysis, IPIs ≥ 120 months remained associated with early preterm birth and LBW.

CONCLUSION

Evidence for adverse associations with twin birth outcomes was strongest for long IPIs.

Cardiac findings in newborn twins

AIMS

To evaluate cardiac findings in newborn twins from the general population and investigate if newborn twins may require systematic evaluation of cardiac parameters.

METHODS

Prospective cohort study of newborns with cardiac evaluation performed during the first month of life. Cardiac findings were compared 1:3 with matched singletons.

RESULTS

We included 412 newborn twins (16% monochorionic; 50% boys) and 1236 singletons. Comparing cardiac findings showed twins had an increased prevalence of non-severe structural heart disease (most common: ventricular septal defects in both groups), thinner left ventricular posterior wall in diastole (LVPWd; 1.82 vs. 1.87 mm, p = 0.02), smaller diameter of the left atrium (10.6 vs. 11.1 mm, p = 0.04), higher heart rate (148 vs. 144 bpm, p = 0.04), more left-shifted QRS axis (106 vs. 111°, p < 0.001), and lower maximum R-wave amplitude in V1 (927 vs. 1015 μV, p = 0.02) compared to singletons. After multifactorial adjustment for potential confounders, the effect of twinning on cardiac parameters persisted only for LVPWd (p < 0.05).

CONCLUSION

Despite contemporary surveillance, we found an increased prevalence of non-severe structural heart disease in a population-based cohort of newborn twins. However, the effect of twinning on cardiac parameters was modest and generally did not persist after correction for likely confounding factors.

Diagnosis-Related Group Weight and Derived Case Mix Index to Assess the Complexity among Twins

OBJECTIVE

Diagnosis-related groups (DRGs) are used to summarize hospital morbidity and mortality. Each DRG has a weight which is important in calculating the case mix index (CMI), a numeric summary of disease complexity in a population of patients. We utilized DRG weight and resultant CMI to compare postnatal outcomes among singletons versus monochorionic and monoamniotic, monochorionic diamniotic, and dichorionic diamniotic twins.

STUDY DESIGN

This single-center and retrospective cohort study evaluated DRGs assigned by the investigators, birth weight, gestational age, length of stay (LOS), NICU admission rate, and mortality in twin births between 2014 and 2016. Twins were analyzed depending on chorionicity and amnionicity. Overall, 3 months of singleton births served as the control. The CMI derived from DRG weights were compared across groups.

RESULTS

Twins (n = 288) had lower gestational ages and birth weights and higher mortality, LOS, NICU admission rates and DRG weights/CMI compared with singletons (n = 327; p < 0.001 for each). The LOS was no different between twin subtypes; monochorionic monoamniotic twins had the highest mortality and DRG weight (p < 0.001).

CONCLUSION

DRG weight and CMI values summarize in-hospital complexity and can be a useful tool to evaluate differences in care complexity among groups of patients.

KEY POINTS

· Using diagnosis-related group and case mix index to assess morbidities.. · Morbidities of twins are monochorionic-monoamniotic versus monochorionic-diamniotic versus dichorionic-diamniotic twins.. · Only seven diagnosis-related group in neonatology make it a valuable tool for clinicians..

Identical twins carry a persistent epigenetic signature of early genome programming

Monozygotic (MZ) twins and higher-order multiples arise when a zygote splits during pre-implantation stages of development. The mechanisms underpinning this event have remained a mystery. Because MZ twinning rarely runs in families, the leading hypothesis is that it occurs at random. Here, we show that MZ twinning is strongly associated with a stable DNA methylation signature in adult somatic tissues. This signature spans regions near telomeres and centromeres, Polycomb-repressed regions and heterochromatin, genes involved in cell-adhesion, WNT signaling, cell fate, and putative human metastable epialleles. Our study also demonstrates a never-anticipated corollary: because identical twins keep a lifelong molecular signature, we can retrospectively diagnose if a person was conceived as monozygotic twin.

Prospective risk of stillbirth and neonatal complications for monochorionic diamniotic and dichorionic diamniotic twins after 24 weeks of gestation

INTRODUCTION

Our study compared the prospective risks of intrauterine fetal death (IUFD), neonatal death (NND), perinatal death (PND), and neonatal morbidities in monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies.

METHODS

This retrospective cohort study included twin pregnancies who had antenatal care and delivery in a public hospital from 2011 to 2018. Exclusion criteria included monoamnionicity, one/both twin miscarriage, twin-twin transfusion syndrome, or lethal congenital abnormalities. All twins were managed in multiple pregnancy clinic with standardized protocols. Gestational age-specific IUFD, NND, PND, and neonatal morbidity rates were compared according to chorionicity.

RESULTS

Three hundred seventy-eight MCDA and 1282 DCDA twins were included. MCDA twins had higher risks of PND (1.9% vs. 0.7% in DCDA twins, p = 0.05), composite neonatal morbidity (p = 0.01), preterm delivery (p < 0.01), and low birth weight (p < 0.01). The prospective risk of IUFD was 0.6% and 0.4% for MCDA and DCDA twins, respectively after 34 weeks' gestation. No NND occurred among deliveries after 30 weeks. The risk of neonatal morbidity of MCDA twins fell from 22.7% at 34 weeks to 2.7% at 37 weeks (p < 0.01). For DCDA twins, the risk of morbidity fell insignificantly from 36 to 38 weeks (4.0% vs. 3.4%, p = 0.60). Logistic regression analysis suggested that the increased risk of perinatal morbidities was related to the higher rate of preterm delivery in MCDA twins rather than chorionicity.

CONCLUSION

With close fetal monitoring, the risk of late IUFD in twin pregnancies without major complications is low. Perinatal morbidity can be minimized by avoiding late preterm deliveries in twin pregnancies.

Twin pregnancy in women with epilepsy

OBJECTIVE

We report data from the Raoul Wallenberg Australian Register of Antiepileptic Drugs in Pregnancy (APR) to see if there are significant differences in relation to the courses and outcomes of the twin pregnancies contained in the register, as compared with the singleton ones.

METHODS

The APR has been under the oversight of Melbourne institutional Human Ethics Research Committees; all women enrolled in the APR have provided written informed consent. Data from the APR were transferred to a spreadsheet and then analyzed using simple statistical techniques including logistic regression.

RESULTS

The population studied comprised 44 twin and 2261 singleton pregnancies; thus, twin pregnancies accounted for 1.91% of all pregnancies studied. The women carrying twins tended to be older than the women with singleton pregnancies to a statistically significant extent, their pregnancies more often originated from assisted fertilization techniques, and their babies were more often delivered by cesarean section. There were no statistically significant differences in relation to antiepileptic drug (AED) therapy. Individual twins had statistically significantly lower mean birthweights than singleton babies and they were statistically significantly more often involved structurally malformed foetuses. In the first year of life, the twin pregnancies statistically significantly more often produced offspring that were affected by seizures in infancy.

SIGNIFICANCE

The data suggest that there may be an increased hazard of fetal malformation in the offspring of twin pregnancy in women with epilepsy, but that with contemporary standards of management of epilepsy and pregnancy, there is unlikely to be an increased hazard of seizure-affected pregnancy.

Notching and Pulsatility Index of the Uterine Arteries and Preeclampsia in Twin Pregnancies

Increased uterine artery Doppler indices have been shown to be associated with preeclampsia and adverse pregnancy outcomes in singleton and twin pregnancies. At 20–22 weeks of gestation, we assessed the use of notching, the highest, lowest, and mean pulsatility index (PI), and the combination of notching and PI of the uterine arteries to screen for preeclampsia. This was done in a cohort of 380 twin pregnancies. The results showed that the combination of notching and the highest PI above the 95th centile of the uterine arteries gives the best screening characteristics for preeclampsia in twin pregnancies. We calculated sensitivities for preeclampsia for notching, highest PI, and the combination of notching and the highest PI of 50%, 45% and 91%, with specificities of 96%, 96% and 93%, respectively. The present findings demonstrate that notching, increased highest PI, and the combination of notching and the highest PI of the uterine arteries is associated with an increased risk of preeclampsia in twin pregnancies. We observed the highest sensitivity and specificity by using the combination of notching and the highest PI of the uterine arteries.

Foetal therapies and their influence on preterm birth

Foetal therapy aims to improve perinatal survival or to prevent severe long-term handicap. Foetal medicine opens a new territory by treating the foetus as a patient. The mother has nothing to gain in terms of health benefits, yet she is inherently also undergoing treatment. In utero foetal interventions can be divided into ultrasound-guided minimally invasive procedures, fetoscopic procedures and open hysterotomy procedures, which carry an inherent risk of ruptured membranes and preterm birth. In this review, we summarise the conditions that may benefit from foetal therapy and review the current therapies on offer, each with their associated risk of ruptured membrane and preterm birth. We also look into some risk limiting and preventative strategies to mitigate these complications.

Double trouble? Clinic-specific risk factors for monozygotic twinning

OBJECTIVE

To investigate clinic-specific risk factors for monozygotic twinning (MZT) using a large, electronic database.

DESIGN

Retrospective case-control study.

SETTING

Infertility clinics.

PATIENT(S)

Using an electronic medical record system, viable clinical pregnancy (confirmation of a gestational sac(s) and presence of at least one fetal pole with a heartbeat on first trimester ultrasound), data were obtained from homologous in vitro fertilization (IVF) cycles after single ET from June 1, 2004, to December 31, 2016. Monozygotic twinning was defined as a pregnancy with two fetal heartbeats on ultrasound with sex concordance at birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Risk factors for MZT including cycle type, method of insemination, and method of cryopreservation.

RESULT(S)

Of the 28,265 IVF cycles that met inclusion criteria over the study period, 8,749 (31.0%) resulted in a viable intrauterine clinical pregnancy. There were 102 (2.7%) MZT in the fresh cycle cohort and 133 (2.7%) in the frozen cycle cohort. Neither cryopreservation nor the method of cryopreservation was a significant risk factor for MZT. However, the use of sequential media was an independent risk factor for MZT in fresh, but not frozen, ETs (odds ratio = 1.72, 95% confidence interval, 1.10-2.68). Significant differences were seen in the incidence of MZT between clinics, and this difference persisted after controlling for known risk factors (clinic 0, reference; clinic 2, odds ratio = 2.22; 95% confidence interval, 1.48-3.32; clinic 3, odds ratio = 1.93; 95% confidence interval, 1.30-2.87).

CONCLUSION(S)

Differences in MZT rates exist between individual IVF clinics, suggesting that variations in practice patterns may contribute to this event. The present study noted the use of sequential media was an independent risk factor for fresh but not frozen cycles.

Birth weight percentiles by sex and gestational age for twins born in southern China

Mean birth weight of twins is known to be lower than that of singletons, however, southern China lacks a twin-specific birth weight reference. In this paper, we use data from the Birth Certificate System in southern China, collected between January 1^st 2014 and December 31^st 2017 and including 161,076 twins, to calculate sex- and gestational week-specific birth weight percentiles (the 3^rd, 10^th, 25^th, 50^th, 75^th, 90^th, and 97^th). We applied generalized additive models for location, scale and shape (GAMLSS) when calculating the birth weight percentiles, and calculated percentiles for monochorionic and dichorionic twins separately. We next used data collected between Jan 1st 2018 and Apr 30th 2018, encompassing 12,371 live births, to calculate the SGA and LGA ratios using birth weight references in Australia, South Korea and China (based on birth defects surveillance system) and birth weight percentiles calculated in this study. Compared to dichorionic twins, monochorionic twins had lower birth weights at 25 to 42 weeks of gestation. The calculated SGA and LGA ratios were relatively stable compared to the other references.

Falling perinatal mortality in twins in the UK: organisational success or chance?

In June 2018, Mothers and Babies Reducing Risks through Audits and Confidential Enquiries across the UK (MBRRACE-UK) published a Perinatal Surveillance report of an audit between 2013-2016. This noted that the stillbirth rate for twins nearly halved between 2014-2016; whereas the stillbirth rate for singletons remained static. There was a statistically significant reduction in the rate of stillbirth in twins over this period from 11.07 (95% CI, 9.78-12.47) to 6.16 (95% CI, 5.20-7.24) per 1000 total births. This commentary discusses these observations, the effects of twin chorionicity, and the potential obstetric and neonatal interventions, as well as public health improvements, that may have influenced these findings.

Birth management and fetal outcome in multiple gestation: analysis of 1.444 births

PURPOSE

Since the late 1990s, controversies came up concerning the mode of delivery for multiples births. The twin birth study indicated no difference in maternal and fetal outcome between planned vaginal delivery and planned caesarean section, but did not analyze the influence of maternal and fetal characteristics or the obstetric management in vaginal birth. The purpose of this study is to analyze these parameters regarding fetal outcome.

METHODS

A large-scale retrospective analysis of twin births (n = 1.444) was performed at a university medical center. The analysis included pregnancy, delivery, and maternal and fetal parameters, including pH and base excess (BE) differences between the first- and second-born twin (delta pH, delta BE).

RESULTS

Delta pH correlated significantly with the birth interval for various positions of twins in the womb (p < 0.05). The longer the birth interval, the greater the delta pH with a lower pH of the second twin. Delta BE values were significantly correlated with the birth interval for a combination of twins in cephalic and breech presentation. Furthermore, it could be shown that higher differences in birth weight between the first/second twin are associated with higher delta pH, higher delta BE values (all p < 0.05). We found significantly decreasing delta pH values in vaginal deliveries over secondary and, finally, primary caesarean sections (p < 0.001).

CONCLUSION

We conclude a vaginal delivery of twin appears safe if experienced staff monitor birth weight discrepancies, birth interval, and blood values consequently. A good outcome also for the second twin delivered spontaneously is nevertheless feasible if experienced staff is available.

Lower perinatal mortality in preterm born twins than in singletons: a nationwide study from The Netherlands

BACKGROUND

Twin pregnancies are at increased risk for perinatal morbidity and death because of many factors that include a high incidence of preterm delivery. Compared with singleton pregnancies, overall perinatal risk of death is higher in twin pregnancies; however, for the preterm period, the perinatal mortality rate has been reported to be lower in twins.

OBJECTIVE

The purpose of this study was to compare perinatal mortality rates in relation to gestational age at birth between singleton and twin pregnancies, taking into account socioeconomic status, fetal sex, and parity.

STUDY DESIGN

We studied perinatal mortality rates according to gestational age at birth in 1,502,120 singletons pregnancies and 51,658 twin pregnancies without congenital malformations who were delivered between 2002 and 2010 after 28 weeks of gestation. Data were collected from the nationwide Netherlands Perinatal Registry.

RESULTS

Overall the perinatal mortality rate in twin pregnancies (6.6/1000 infants) was higher than in singleton pregnancies (4.1/1000 infants). However, in the preterm period, the perinatal mortality rate in twin pregnancies was substantially lower than in singleton pregnancies (10.4 per 1000 infants as compared with 34.5 per 1000 infants, respectively) for infants who were born at <37 weeks of gestation; this held especially for antepartum deaths. After 39 weeks of gestation, the perinatal mortality rate was higher in twin pregnancies. Differences in parity, fetal sex, and socioeconomic status did not explain the observed differences in outcome.

CONCLUSION

Overall the perinatal mortality rate was higher in twin pregnancies than in singleton pregnancies, which is most likely caused by the high preterm birth rate in twins and not by a higher mortality rate for gestation, apart from term pregnancies. During the preterm period, the antepartum mortality rate was much lower in twin pregnancies than in singleton pregnancies. We suggest that this might be partially due to a closer monitoring of twin pregnancies, which indirectly suggests a need for closer surveillance of singleton pregnancies.

Intrauterine fetal death in triplet gestation caused by feto-fetal transfusion syndrome - a case report

Feto-fetal transfusion syndrome (FFTS) severely affects monochorionic (MC) multiple pregnancies and affects 1 in 1600 pregnancies overall. The number of increasing disputed obstetrics cases in China is related to unavailability of prompt diagnosis of FFTS. We present here a woman with a MC triplet pregnancy with intrauterine fetal death at 33 weeks of gestation due to FFTS. Subsequent pathological anatomy showed that the MC placenta contained vascular anastomoses, including arterio-arterial anastomosis and arterio-venous anastomosis. These anastomoses led to unidirectional blood flow with the absence of adequate compensatory counter-transfusion and bi-directional flow. When encountering such challenging conditions, medical practitioners should discreetly compare the fetuses' characteristics with features of placental blood vessels and consult morphological and pathological findings. Furthermore, they should perform ultrasound examinations, particularly focussing on fetal size differences and the maximum vertical pocket in the diagnosis of FFTS, especially in MC multiple pregnancies with abdominal symptoms.

Birth weight centiles by gestational age for twins born in south India

Background

Birth weight centile curves are commonly used as a screening tool and to assess the position of a newborn on a given reference distribution. Birth weight of twins are known to be less than those of comparable singletons and twin-specific birth weight centile curves are recommended for use. In this study, we aim to construct gestational age specific birth weight centile curves for twins born in south India.

Methods

The study was conducted at the Christian Medical College, Vellore, south India. The birth records of all consecutive pregnancies resulting in twin births between 1991 and 2005 were reviewed. Only live twin births between 24 and 42 weeks of gestation were included. Birth weight centiles for gestational age were obtained using the methodology of generalized additive models for location, scale and shape (GAMLSS). Centiles curves were obtained separately for monochorionic and dichorionic twins.

Results

Of 1530 twin pregnancies delivered during the study period (1991–2005), 1304 were included in the analysis. The median gestational age at birth was 36 weeks (1st quartile 34, 3rd quartile 38 weeks). Smoothed percentile curves for birth weight by gestational age increased progressively till 38 weeks and levels off thereafter. Compared with dichorionic twins, monochorionic twins had lower birth weight for gestational age from after 27 weeks.

Conclusions

We provide centile values of birth weight at 24 to 42 completed weeks of gestation for twins born in south India. These charts could be used both in routine clinical assessments and epidemiological studies.

The impact of chorionicity on maternal pregnancy outcomes

OBJECTIVE

Women carrying twin pregnancies often receive similar counseling, regardless of chorionicity, with the notable exception of twin-twin transfusion syndrome (TTTS); however, little is known about whether the presence of 1 vs 2 placentas confers dissimilar maternal risks. We sought to determine differences in maternal and neonatal outcomes based on chorionicity.

STUDY DESIGN

This was a retrospective cohort study of all twin pregnancies at our institution undergoing routine second-trimester ultrasound for anatomic survey from 1990 through 2010. Secondary outcomes included other adverse maternal and neonatal outcomes. Relative risks and adjusted odds ratios (aORs) were calculated. Cluster analysis was used to account for nonindependence of twin pairs.

RESULTS

Of 2301 pregnancies, 1747 (75.9%) were dichorionic and 554 (24.1%) were monochorionic. Rates of preeclampsia, gestational diabetes, placental abruption, placenta previa, preterm labor, and preterm premature rupture of membranes (PPROM) were not significantly different in dichorionic vs monochorionic pregnancies. Early preterm delivery less than 34 weeks (aOR, 1.47; 95% confidence interval [CI], 1.17-1.86) and less than 28 weeks (aOR, 2.58; 95% CI, 1.58-4.20) were more likely in monochorionic twins, as was neonatal intensive care unit admission (aOR, 1.41; 95% CI, 1.12-1.78). Monochorionic twins delivered earlier at a mean gestational age of 34.2 weeks vs 35.0 weeks for dichorionic twins (P < .001). Hospital length of stay was significantly longer for monochorionic twins with a mean of 13.7 days vs 10.8 days for dichorionic twins (P = .01).

CONCLUSION

There are no significant differences in maternal outcomes by chorionicity; however, monochorionicity is associated with increased fetal risks. This information may be helpful in guiding more targeted counseling to expectant parents of twins that, although the presence of an additional placenta does not confer additional maternal risks, monochorionic infants tend to deliver earlier and require longer hospital stays.

Outcome of fetoscopic laser ablation for twin-to-twin transfusion syndrome in dichorionic-triamniotic triplets compared with monochorionic-diamniotic twins

OBJECTIVE

To compare outcome of dichorionic-triamniotic (DCTA) triplet gestations with that of a paired cohort of monochorionic-diamniotic (MCDA) twin gestations undergoing laser therapy for treatment of twin-to-twin transfusion syndrome (TTTS).

METHODS

All DCTA triplets treated at four referral centers between specified dates were included. A matched cohort group of MCDA twin gestations affected by TTTS was used for comparison.

RESULTS

Sixteen sets of DCTA triplets treated with laser photocoagulation of placental anastomoses were compared with 32 matched sets of MCDA twins. All of the 'singleton' fetuses in the triplet gestations survived to birth and to the end of the neonatal period. There were no differences in single or double survival or the rate of non-survivors to birth and at age 28 days. A mean 3-week difference was found in the procedure-to-delivery interval in DCTA triplets vs MCDA twins (60 ± 35.8 days vs 83.6 ± 33.2 days; P = 0.029). A mean difference of 3 weeks was also found in the gestational age at delivery in DCTA triplets vs MCDA twins (28.5 ± 3.5 weeks vs 31.9 ± 5 weeks; P = 0.024). A similar post-laser fetal growth pattern in donors and recipients of both groups was noted.

CONCLUSIONS

DCTA triplet gestations with TTTS have a similar rate of post-laser survival but deliver earlier than can be expected for twins treated with laser. These findings have potential implications for the risk of prematurity and long-term outcomes.

Umbilical and fetal middle cerebral artery Doppler reference ranges in a twin population followed longitudinally from 24 to 38 weeks' gestation

OBJECTIVE

To construct monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin reference ranges for umbilical artery (UA) pulsatility index (PI), UA resistance index (RI), fetal middle cerebral artery (MCA) PI and peak systolic velocity (PSV) and cerebroplacental ratio (CPR) from 24 weeks' to 38 weeks' gestation and compare these with published normal values for singleton pregnancies.

METHODS

This prospective multicenter cohort study included 1028 unselected twin pairs recruited over a 2-year period. Participants with dichorionic twins underwent fortnightly ultrasound surveillance from 24 weeks' gestation, with monochorionic twins being followed every 2 weeks from 16 weeks until delivery. A total of 7536 fetal Doppler examinations in 618 twin pregnancies were included in the analysis, with reference ranges for MCDA and DCDA pregnancies constructed for each of the Doppler indices using multilevel modeling.

RESULTS

UA-PI and UA-RI appear to be higher in twins than in singletons, and MCA-PI and MCA-PSV appear to be lower. The CPR also appears to be lower in twins than in singletons. Similar MCA indices were observed in MCDA and DCDA twins.

CONCLUSION

We have established longitudinal reference ranges for UA-PI and UA-RI, MCA-PI and MCA-PSV and CPR in twin pregnancies, which appear to differ from those in singleton pregnancies. The derived twin-specific reference ranges may be more appropriate in the surveillance of these high-risk pregnancies. Applying the singleton CPR cut-off of ≤ 1.0 may lead to a large number of false-positive diagnoses of cerebral redistribution in twin fetuses.

[Perinatal outcome of monochorionic and dichorionic twin gestations: a study of 775 pregnancies at Reunion Island]

OBJECTIVES

To compare the perinatal mortality and morbidity of infants born from monochorionic versus dichorionic twin pregnancies (TP).

PATIENTS AND METHODS

Retrospective, comparative study of monochorionic and dichorionic TP over 10 years in the south of Reunion Island. Information regarding demographic, gestational and perinatal variables of mothers and infants was collected from the hospital perinatal database.

RESULTS

Six hundred and twenty dichorionic and 155 monochorionic TP were analyzed. In case of monochorionic TP, mothers had higher rates of pregnancy-related hypertension (OR=1.82, 95%CI=[1.02-3.29] ; P=0.03) and hospitalization (OR=1.48, 95%CI=[1.02-2.16]; P=0.03). Newborns from monochorionic TP had higher morbidity for : very preterm birth (birth before 33 weeks gestation) (OR=1.65, 95%CI=[1.02-2.66]; P=0.02), very low birth weight (birth weight<1500g) (OR=1.73, 95%CI=[1.57-3.13]; P<0.001), Apgar<7 at 1 minute (OR=1.76, 95%CI=[1.18-2.61]; P<0.01) and hospitalization (OR=2.08, 95%CI=[1.58-2.73]; P<0.001). Perinatal mortality was also significantly higher (OR=2.47, 95%CI=[1.54-3.94]; P<0.001), as well intrauterine fetal death (OR=3.96, 95%CI=[1.95-8.05]; P<0.001) CONCLUSION: This study confirms that few differences exist among dichorionic and monochorionic TP with regard to maternal morbidity, while neonatal morbidity and mortality are higher in twins born from monochorionic pregnancies.

Does risk of preeclampsia differ by twin chorionicity?

OBJECTIVE

Examine whether dichorionic (DC) and monochorionic (MC) twins exhibit different rates and severity of preeclampsia.

METHODS

Retrospective cohort study of 695 twin pregnancies from 2002 to 2007. DC pregnancies were compared to MC pregnancies, with the primary outcome of interest being development of preeclampsia, and the secondary outcome being severity of preeclampsia. Chi square test compared proportions and multivariable analyses controlled for potential confounders.

RESULTS

Any preeclampsia developed in 21.1% (104/492) of DC and 10.8% (22/203) of MC pregnancies (p = 0.001), mild preeclampsia in 13.8% (68/492) of DC and 4.9% (10/203) of MC pregnancies (p = 0.001) and severe preeclampsia in 7.3% (36/492) of DC and 5.9% (12/203) of MC pregnancies (p = 0.506). DC pregnancies showed higher odds of mild preeclampsia compared to MC pregnancies (aOR 5.85, 95% CI 1.31-26.13) after controlling for several potential confounders including gestational age at delivery.

CONCLUSIONS

A statistically significant larger proportion of women with DC twins developed any preeclampsia, and specifically mild preeclampsia, compared to those with MC twins. Additionally, after controlling for several potential confounders, women with DC pregnancies demonstrated higher odds of developing mild preeclampsia compared to those with MC pregnancies. Mechanisms of preeclampsia development may differ by twin chorionicity.

Multiple pregnancies in CKD patients: an explosive mix

BACKGROUND AND OBJECTIVES

CKD and multiple pregnancies bear important risks for pregnancy outcomes. The aim of the study was to define the risk for adverse pregnancy-related outcomes in multiple pregnancies in CKD patients in comparison with a control group of "low-risk" multiple pregnancies.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study was performed in the Maternal Hospital of the University of Turin, Italy. Of 314 pregnancies referred in CKD (2000-2011), 20 were multiple (15 twin deliveries). Control groups consisted of 379 low-risk multiple pregnancies (314 twin deliveries) and 19 (15 twin deliveries) cases with hypertension-collagen diseases. Baseline data and outcomes were compared by univariate and logistic regression analyses.

RESULTS

The prevalence of multiple pregnancies was relatively high in the CKD population (6.4%); all referred cases were in early CKD stages (I-II); both creatinine (0.68 to 0.79 mg/dl; P=0.010) and proteinuria (0.81 to 3.42 g/d; P=0.041) significantly increased from referral to delivery. No significant difference in demographic data at baseline was found between cases and low-risk controls. CKD was associated with higher risk of adverse pregnancy outcomes versus low-risk twin pregnancies. Statistical significance was reached for preterm delivery (<34 weeks: 60% vs 26.4%; P=0.005; <32 weeks: 53.3% vs 12.7%; P<0.001), small for gestational age babies (28.6% vs 8.1%; P<0.001), need for Neonatal Intensive Care Unit (60% vs 12.7%; P<0.001), weight discordance between twins (40% vs 17.8%; P=0.032), and neonatal and perinatal mortality (6.6% vs 0.8%; P=0.032).

CONCLUSION

This study suggests that maternal-fetal risks are increased in multiple pregnancies in the early CKD stages.

Clinicians learn less and less about more and more until they know nothing about everything; researchers learn more and more about less and less until they know everything about nothing: discuss

A number of recent developments in our understanding of the biology of heritability question commonly held views on the immutability of genetic factors. These have numerous potential implications for improving understanding and practice in pre- and postconceptional care and for infant and child mental health, and they carry a cautionary message against overgeneralization.

Renal failure of the surviving fetus after intrauterine death of the co-twin

Twin pregnancies are considered at a higher risk for fetal mortality than singleton pregnancies. The antenatal death of one of the twins is associated with an increasing rate of cerebral impairment and lesions in other organs in the surviving fetus, especially if the pregnancy is monochorionic. We describe a case of isolate renal failure becoming evident gradually after birth in a surviving twin after the antenatal death of the co-twin. Considering the deleterious effects of vascular disruption in a surviving twin, our findings suggest careful investigation of renal function, even if no intrauterine signs of diminished renal function were previously detected.

Twins--twice more trouble?

Twin gestations are fascinating and are also high-risk pregnancies. They account for approximately 3% of all pregnancies in the United States. Major obstetrical complications associated with twin pregnancies include hypertensive disorders of pregnancy, gestational diabetes, and preterm delivery. In addition, the death rate for twins and the rate of severe handicap in very low birth weight survivors of twin pregnancies is greater than that for singleton pregnancies. Ultrasound allows for stepwise evaluations at any time during a twin gestation. Current evidence suggests that uncomplicated diamniotic twins with concordant and appropriate growth beyond 24 weeks' gestation should be managed conservatively and the time and mode of delivery should be determined on the basis of obstetrical history and fetal presentations. Perinatal management of the remaining twin pregnancies depends on good clinical judgment, which is improved by the use of ultrasound imaging.

Influence of chorionicity on perinatal outcome in a large cohort of Danish twin pregnancies

OBJECTIVE

To assess outcome in twin pregnancies according to chorionicity.

METHODS

A cohort was retrieved from local ultrasound databases at 14 obstetric departments in Denmark, comprising all twin pregnancies with two live fetuses scanned between weeks 11 and 14 in the period 1 January 2004 to 31 December 2006. Outcome data were retrieved from the National Board of Health.

RESULTS

Among 2038 twin pregnancies, 1757 (86.2%) were dichorionic (DC) and 281 (13.8%) were monochorionic diamniotic (MC). In MC pregnancies, the rate of spontaneous fetal loss in both second and third trimesters was more than threefold higher than the comparable rate in DC pregnancies: 6.0% vs. 1.9% for at least one fetus in the second trimester (P < 0.001) and 2.1% vs. 0.7% in the third trimester (P = 0.03). In 98.4% of DC pregnancies and in 91.1% of MC pregnancies, at least one infant was liveborn. Amongst pregnancies with two live fetuses at 24 weeks, the proportion with two live infants at 28 days after delivery was 97.5% and 95.1%, respectively.

CONCLUSIONS

The increased incidence of fetal loss in MC pregnancies compared with DC pregnancies predominantly occurs before 24 weeks' gestation. After this stage, although the risk of intrauterine fetal death is still higher in MC than in DC pregnancies, if both fetuses are alive at 24 weeks, the chance of a woman having two live infants 1 month after delivery is similar in MC and DC pregnancies.

Mean, lowest, and highest pulsatility index of the uterine artery and adverse pregnancy outcome in twin pregnancies

OBJECTIVE

The objective of the study was to assess the use of mean, lowest, and highest pulsatility index (PI) of the uterine arteries to screen for adverse pregnany outcome in twin pregnancies.

STUDY DESIGN

This was a screening study of 423 twin pregnancies. Relationship between PI at 20-22 weeks and adverse pregnancy outcome was evaluated.

RESULTS

Mean, lowest, and highest PI above the 95th centile were significant risk factors for preeclampsia and adverse pregnancy outcome in monochorionic and dichorionic twins. We calculated a sensitivity for preeclampsia for mean, highest, and lowest PI of 35%, 29%, and 27%, respectively.

CONCLUSION

Increased mean, lowest, and highest PI is associated with a higher risk of preeclampsia and adverse pregnancy outcome in twins. We observed the highest sensitivity and specificity by using highest PI. The high incidence of preeclampsia in twins makes it attractive to use the PI of the uterine artery for risk stratification in twins.

Fetal death in twins

OBJECTIVE

To examine the pattern and prospective risk of intrauterine fetal death (IUFD) in twin pregnancy by chorionicity.

DESIGN

Retrospective cohort analysis.

SETTING

Large national tertiary referral center.

POPULATION

All consecutive twin deliveries (1997-2006) ≥24 weeks.

METHODS

Retrospective review of all consecutive twin deliveries over 10 years to identify patterns of IUFD in twins and calculate gestation-specific prospective risks of IUFD. Fetal death was defined as intrauterine demise of a fetus ≥24weeks, intertwin birthweight discordance as ≥20% difference and growth restriction as birthweight <5(th) centile. Chorionicity was confirmed by postnatal placental examination.

MAIN OUTCOME MEASURES

Fetal death.

RESULTS

1094 twin pairs including 276 monochorionic-diamniotic (MCDA) (25.3%) and 818 dichorionic-diamniotic (DCDA) twin pregnancies (74.7%) were studied. Twenty-nine fetal deaths occurred affecting 22 twin pregnancies. The incidence of IUFD (death of one or both fetuses) in MCDA twin pregnancies was three times that in DCDA pregnancies [11/276 (3.9)% vs. 11/818 (1.3%) p<0.001]. The majority of deaths in MCDA twins were associated with twin-twin transfusion syndrome (TTTS) prior to 30 weeks. In normally grown twins the prospective risk of IUFD was similarly low in MCDA and DCDA pregnancies after 34 weeks but in pregnancies complicated by abnormal growth, the prospective risk of IUFD was 3.4 in MCDA and 2.0 in DCDA pregnancies.

CONCLUSION

Twin pregnancies complicated by growth restriction or growth discordance were associated with a high risk of IUFD, particularly in affected MCDA twins. Conversely, in normally grown twins the risk was similarly low in MCDA and DCDA pregnancies after 34 weeks.

MTHFR C677T and A1298C polymorphisms and cerebral stroke in two twin gestations

BACKGROUND

Stroke in pediatric age is a rare event with a multifactorial genesis which could involve genetic factors as methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphism. At the same time, twin gestation with co-twin demise is an important potential risk factor for premature brain damage.

PATIENTS AND METHODS

We describe two children presenting with presumed cerebral stroke born from two MC twin pregnancies in which the other co-twin had died in utero associated to maternal and fetal homozygosity for MTHFR C677T and MTHFR A1298C, respectively. Brain damage was diagnosed immediately before the delivery.

CONCLUSION

Our observations underline the necessity to make a thrombophilia workup in women before or during pregnancy and, above all, in twin pregnancy. Data of literature are not clear about what kind of genetic polymorphism is prominent in the genesis of cerebral stroke (factor V leiden, MTHFR, activated protein C resistance, factor II G20210A). A multifactorial genesis for severe fetal and perinatal cerebral vascular alterations has been supposed; for this reason an early folate supplementation both to mother and infant could reduce the risk of brain damage due to fetal/perinatal stroke and eventual recurrence of thrombotic events.

Uncomplicated monochorionic diamniotic twin pregnancy

There have been significant advances in our understanding of the aetiology and management of disorders specific to Monochorionic Diamniotic (MCDA) twin pregnancies like Twin-Twin Transfusion Syndrome (TTTS) and Twin Reversed Arterial Perfusion (TRAP) but there is paucity of data about the management of uncomplicated MCDA twins pregnancies. It is accepted that even in the absence of specific complications, these pregnancies are associated with increased perinatal morbidity & mortality. The aim of this review is to gather evidence regarding the management of seemingly uncomplicated monochorionic diamniotic pregnancies.

Epidemic of plurality and contributions of assisted reproductive technology therein

A commentary on contributions of ART to the pandemic of multiple gestations is presented and mechanistic aspects therein are explored.

The value of umbilical artery Doppler velocimetry in the antenatal surveillance of uncomplicated monochorionic twin pregnancies

OBJECTIVES

To investigate the predictive value of abnormal umbilical artery Doppler findings on outcome in uncomplicated monochorionic (MC) twin pregnancies.

METHODS

Sixty-seven MC twin pregnancies, with antenatal care and delivery at the University Medical Center, Utrecht, The Netherlands, between 1999 and 2004, were studied. Pregnancies with antenatal signs of twin-to-twin transfusion syndrome were excluded. We analyzed the data according to both the last Doppler measurement of the umbilical artery before delivery and the presence of any abnormal Doppler measurement during the course of pregnancy. Risks of mortality and total neonatal morbidity were stratified according to the Doppler findings in one or both fetuses at the time of each standard ultrasound assessment in order to estimate the risk associated with an abnormal Doppler finding at or before that specific gestational age.

RESULTS

Mortality rates were similar in the normal and abnormal Doppler groups. Using both group definitions, total neonatal morbidity was higher in the abnormal Doppler group; this was significant at > 32 weeks' gestation, and was due to lower birth weight and earlier gestational age at delivery. There was no mortality at > or = 36 weeks in the abnormal Doppler group, but there were four perinatal deaths in the normal Doppler group. Gestational age at delivery was significantly lower when one or more abnormal Doppler findings had been present (median, 34 + 1 weeks vs. 36 + 3 weeks) and infants with abnormal Doppler findings weighed on average 261 g (95% CI, 21-502 g) less than those with normal findings.

CONCLUSIONS

In MC twins, abnormal Doppler flow of the umbilical artery identifies a subgroup at risk for preterm delivery, low birth weight and neonatal morbidity, but with a similar mortality risk to those with normal Doppler flow. At term, mortality occurred only in the group with normal Doppler findings, suggesting that fetal surveillance is insufficient in uncomplicated term MC twin pregnancies.

Increased perinatal mortality and morbidity in monochorionic versus dichorionic twin pregnancies: clinical implications of a large Dutch cohort study

OBJECTIVE

To evaluate mortality and morbidity in a large cohort of twin pregnancies according to chorionicity. We aimed to estimate the optimal time of delivery.

DESIGN

Historical cohort design. Setting Two teaching hospitals.

POPULATION

Twin pregnancies delivered in the University Medical Centre, Utrecht, and the St Elisabeth Hospital, Tilburg (1995-2004), The Netherlands (n = 1407).

METHODS

Pregnancy outcomes were documented according to chorionicity. Mortality >/=32 weeks was reviewed carefully with special attention to antenatal fetal monitoring, autopsy and placental histopathology to find an explanation for adverse outcome.

MAIN OUTCOME MEASURES

Perinatal mortality and morbidity in monochorionic (MC) and dichorionic (DC) twins.

RESULTS

Perinatal mortality was 11.6% in MC twin pregnancies and 5.0% in DC twin pregnancies. After 32 weeks, the risk of intrauterine death (IUD) was significantly higher in MC twins than in DC twins (hazard ratio 8.8, 95% CI 2.7-28.9). In most of these cases of IUD, no antenatal signs of impaired fetal condition had been present. Median gestational age was 1 week longer in DC twins than in MC twins, and the mean birthweight was 221 g higher. Severe birthweight discordancy (>20%) occurred more often in MC twins than in DC twins (OR 1.23, 95% CI 0.97-1.55). The incidence of necrotising enterocolitis (NEC) was higher in MC twins, after adjustment for age and weight at birth (OR 4.05, 95% CI 1.97-8.35). There was a trend towards higher neuromorbidity in MC twins.

CONCLUSIONS

This is the largest cohort study of twin pregnancies evaluating outcome according to chorionicity thus far. MC twins are at increased risk for fetal death (even at term), NEC and neuromorbidity. Current antenatal care is insufficient to predict and prevent this excess perinatal mortality and morbidity. Planned delivery at or even before 37 weeks of gestation seems to be justified for MC twins.

Prenatal influences on brain dopamine and their relevance to the rising incidence of autism

The incidence of autism has risen 10-fold since the early 1980s, with most of this rise not explainable by changing diagnostic criteria. The rise in autism is paradoxical in that autism is considered to be one of the most genetically determined of the major neurodevelopmental disorders and should accordingly either be stable or even declining. Because a variety of epigenetic influences, particularly those occurring during the prenatal period, can override or masquerade as genetic influences, these should be considered as prime contributors to the recent increase of autism. Prenatal influences on dopamine activity are especially well-documented, including the effects of maternal psychosocial stress, maternal fever, maternal genetic and hormonal status, use of certain medications, urban birth, and fetal hypoxia. All of these factors have been implicated in the genesis of autism, which is characterized by a "hyperdopaminergic" state based on evidence from monkey and human behavioral studies, pharmacological studies in humans, and a left-hemispheric predominance of both dopamine and autistic-like symptoms. Chronically high maternal levels of dopamine caused by the pressures of increasingly urbanized societies and by changing maternal demographics such as increased workforce participation, educational achievement level, and age at first birth, may be especially significant epigenetic contributors to the recent autism rise.

Monochorionic diamniotic infants without twin-to-twin transfusion syndrome

BACKGROUND

Monochorionic-diamniotic twins (MoDi) occur in 0.3% of all pregnancies. Twin-to-twin transfusion syndrome (TTS) that occurs in 20% of MoDi pregnancies is associated with high perinatal morbidity and mortality. MoDi twins without TTS are more frequent (80%) but have been scarcely reported.

OBJECTIVE

To study perinatal morbidity and mortality of 74 MoDi twin sets without TTS and to compare it to that of 38 sets of MoDi twins with TTS.

METHODS

Chorionicity was determined by gender and placental examination. Gestational age (GA) was set by sonography and pediatric examination. TTS was diagnosed clinically and by sonography, discordance was defined by twins birth weight difference > or =20%, and fetal growth restriction was determined by using a twin-specific nomogram.

RESULTS

MoDi twin pregnancies without and with TTS were similar in demographics, live births, history of preeclampsia, fetal distress and cesarean delivery. They were different (p<0.01) in discordant pregnancies (36 and 79%), GA at delivery (32 and 29 weeks) intrauterine growth restriction (39 and 89%) and neonatal mortality (12 and 36%). Concordant (47 sets) and discordant (27 sets) MoDi twins without TTS were clinically similar.

CONCLUSIONS

MoDi twins without TTS have high rates of birth weight discordance, fetal growth restriction, fetal distress, prematurity and cesarean delivery. Although their perinatal mortality is low, the reported occurrence and the short- and long-term impacts of fetal and neonatal morbidities warrants attention.

An association of chorionicity with preterm twin birth

OBJECTIVE

To assess the risk factors for preterm birth in twin pregnancies, particularly monochorionicity.

METHODS

A cohort study of 767 sets of twins, each twin weighing more than 500 g, born between January 1, 1992, and December 31, 2001, at St. Joseph's Health Care in London, Ontario. Statistical analysis was performed using forward stepwise logistic regression models, with gestational age at birth less than 28 or 32 weeks as the outcome.

RESULTS

Polyhydramnios and chorioamnionitis were significant risk factors for preterm birth prior to 28 or 32 weeks' gestation. Monochorionicity was a risk factor for preterm birth prior to 32 weeks' gestation. Past term birth and maternal age over 30 years were associated with reduced risk for preterm birth.

CONCLUSION

Monochorionic placentation is a significant risk factor for preterm twin birth.

Mean arterial pressure in concordant and discordant triplets during the first week of life

OBJECTIVE

To retrospectively determine mean arterial pressure (MAP) for stable concordant and discordant triplets during the first 7 days of life.

BACKGROUND

Morbidity and mortality for prematurely born triplets is high, therefore, MAP monitoring during the first day of life is important for their clinical management. MAP reference values for special populations such as triplets have not been published. Recently, we reported that in stable discordant twins MAP values during the first day of life were significantly lower in the smaller than in their larger siblings. Comparable information for triplets is not available.

DESIGN

Retrospective cohort study.

METHODS

We studied 30 sets of concordant and 29 sets of discordant (birth weight difference > or =20%) consecutively born triplets. Stable patients were defined as those having umbilical cord hemoglobin > or =13 g/dl, normal blood gases, who were never treated for hypotension, and survived at least 7 days. MAP (torr) were measured by oscillometry in 3410, and by transducer via an umbilical arterial catheter in 1251 instances.

RESULTS

Concordant and discordant triplets were similar in demographics, history of preterm labor (63 and 63%), chorioamnionitis (10 and 10%), pre-eclampsia (53 and 48%), cesarean delivery (100 and 100%), antenatal steroids (77 and 73%), cord hemoglobin (16 and 16 g/dl), combined triplets birth weight (4922 and 4732 g), gestational age (32 and 33 weeks), normal head ultrasounds or Grade I intracranial hemorrhage (96 and 100%) and neonatal mortality (2 and 1%), but were different in the number of infants requiring mechanical ventilation (57 and 31%). A total of 80 (89%) concordant triplets and 77 (88%) discordant triplets were stable according to our definition. Concordant stable triplets, whether small, medium or large, had similar MAP at birth. Their MAP values increased noticeably from birth to 24 hours and more subtlely to 7 days. Triplets of < or =32 weeks GA had lower MAP throughout than those of > or =33 weeks GA. Discordant stable triplets were divided into 27 small (1382 g), 26 medium (1683 g) and 27 large (1969 g); during the first 24 hours, medium and smaller triplets had MAP values that were lower than those of their larger siblings. From the second to the seventh day of life, all MAP values and trends were similar. Among discordant triplets, 86% of the smallest, 13% of the medium and 13% of the largest infants had asymmetrical intrauterine growth restriction.

CONCLUSION

In stable concordant and stable discordant triplets, MAP correlates with birth weight, gestational age and postnatal age. MAP values increase noticeably during the first 24 hours and more subtlely during the next 7 days. Concordant or discordant, small, medium, and large triplets have similar MAP values and trends to that of their siblings. Small and medium discordant triplets have lower MAP values during the first day of life than their larger siblings but by the second day there MAP trends and values were no longer different.