The North of England Survey of Twin and Multiple Pregnancy

India's Opportunities and Challenges in Establishing a Twin Registry: An Unexplored Human Resource for the World's Second-Most Populous Nation

Nature and nurture have always been a prerogative of evolutionary biologists. The environment's role in shaping an organism's phenotype has always intrigued us. Since the inception of humankind, twinning has existed with an unsettled parley on the contribution of nature (i.e. genetics) versus nurture (i.e. environment), which can influence the phenotypes. The study of twins measures the genetic contribution and that of the environmental influence for a particular trait, acting as a catalyst, fine-tuning the phenotypic trajectories. This is further evident because a number of human diseases show a spectrum of clinical manifestations with the same underlying molecular aberration. As of now, there is no definite way to conclude just from the genomic data the severity of a disease or even to predict who will get affected. This greatly justifies initiating a twin registry for a country as diverse and populated as India. There is an unmet need to set up a nationwide database to carefully curate the information on twins, serving as a valuable biorepository to study their overall susceptibility to disease. Establishing a twin registry is of paramount importance to harness the wealth of human information related to the biomedical, anthropological, cultural, social and economic significance.

Effect of monochorionicity on perinatal outcome and growth discordance in triplet pregnancy: collaborative multicenter study in England, 2000-2013

OBJECTIVES

To compare perinatal outcome and growth discordance between trichorionic triamniotic (TCTA) and dichorionic triamniotic (DCTA) or monochorionic triamniotic (MCTA) triplet pregnancies.

METHODS

This was a multicenter cohort study using population-based data on triplet pregnancies from 11 Northern Survey of Twin and Multiple Pregnancy (NorSTAMP) maternity units and the Southwest Thames Region of London Obstetric Research Collaborative (STORK) multiple pregnancy cohort, for 2000-2013. Perinatal outcomes (from ≥ 24 weeks' gestation to 28 days of age), intertriplet fetal growth and birth-weight (BW) discordance and neonatal morbidity were analyzed in TCTA compared with DCTA/MCTA pregnancies.

RESULTS

Monochorionic placentation of a pair or trio in triplet pregnancy (n = 72) was associated with a significantly increased risk of perinatal mortality (risk ratio, 2.7 (95% CI, 1.3-5.5)) compared with that in TCTA pregnancies (n = 68), due mainly to a much higher risk of stillbirth (risk ratio, 5.4 (95% CI, 1.6-18.2)), with 57% of all stillbirth cases resulting from fetofetal transfusion syndrome, while there was no significant difference in neonatal mortality (P = 0.60). The associations with perinatal mortality and stillbirth persisted when considering only pregnancies not affected by a major congenital anomaly. DCTA/MCTA triplets had lower BW and demonstrated greater BW discordance than did TCTA triplets (P = 0.049). Severe BW discordance of > 35% was 2.5-fold higher in DCTA/MCTA compared with TCTA pregnancies (26.1% vs 10.4%), but this difference did not reach statistical significance (P = 0.06), presumably due to low numbers. Triplets in both groups were delivered by Cesarean section in over 95% of cases, at a similar gestational age (median, 33 weeks' gestation). The rate of respiratory (P = 0.28) or infectious (P = 0.08) neonatal morbidity was similar between the groups.

CONCLUSIONS

Despite close antenatal surveillance, monochorionic placentation of a pair or trio in triamniotic triplet pregnancy was associated with a significantly increased stillbirth risk, mainly due to fetofetal transfusion syndrome, and with greater size discordance. In liveborn triplets, there was no adverse effect of monochorionicity on neonatal outcome. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

The risk of twin pregnancies should be minimized in patients with a unicornuate uterus undergoing IVF-ET

Unicornuate uteri are associated with infertility, miscarriage, preterm delivery and even uterine rupture. The aim of this research was to investigate the effects of unicornuate uterine anomaly on twin pregnancies after in vitro fertilization-embryo transfer (IVF-ET). A total of 206 women with unicornuate uteri (A singleton, B selective reduction (SR) of twins to a singleton, C twins) and 314 women with normal uteri (D SR of twins to a singleton, E twins) who delivered at ≥22 weeks were included. C was associated with a significantly lower live birth rate (adjusted odds ratio (aOR) 0.08, 95% confidence interval (CI), 0.01-0.69) and higher risks of preterm delivery (aOR 11.63, 95% CI, 4.85-27.92), perinatal mortality (aOR 11.43, 95% CI, 1.44-90.57) and low birth weight (aOR 5.92, 95% CI 1.94-18.06) than A, a 15-fold greater risk of preterm delivery (aOR 15.54, 95% CI 3.09-78.28) than B and a greater risk of preterm delivery (aOR 2.76, 95% CI 1.33-5.73) than E. After SR to a singleton, the perinatal outcomes were statistically similar between B and D. These results showed that the risk of twin pregnancies should be minimized in patients with unicornuate uterine anomaly undergoing IVF-ET.

Weight discordance and perinatal mortality in monoamniotic twin pregnancy: analysis of MONOMONO, NorSTAMP and STORK multiple-pregnancy cohorts

OBJECTIVES

The primary objective was to quantify the risk of perinatal mortality in non-anomalous monochorionic monoamniotic (MCMA) twin pregnancies complicated by birth-weight (BW) discordance. The secondary objectives were to investigate the effect of inpatient vs outpatient fetal monitoring on the risk of mortality in weight-discordant MCMA twin pregnancies, and to explore the predictive accuracy of BW discordance for perinatal mortality.

METHODS

This analysis included data on 242 MCMA twin pregnancies (484 fetuses) from three major research collaboratives on twin pregnancy (MONOMONO, STORK and NorSTAMP). The primary outcomes were the risks of intrauterine (IUD), neonatal (NND) and perinatal (PND) death, according to weight discordance at birth from ≥ 10% to ≥ 30%. The secondary outcomes were the association of inpatient vs outpatient fetal monitoring with the risk of mortality in weight-discordant pregnancies, and the accuracy of BW discordance in predicting mortality. Logistic regression and receiver-operating-characteristics-curve analyses were used to analyze the data.

RESULTS

The risk of IUD was significantly increased in MCMA twin pregnancies with BW discordance ≥ 10% (odds ratio (OR), 2.2; 95% CI, 1.1-4.4; P = 0.022) and increased up to an OR of 4.4 (95% CI, 1.3-14.4; P = 0.001) in those with BW discordance ≥ 30%. This association remained significant on multivariate logistic regression analysis for BW-discordance cut-offs ≥ 20%. However, weight discordance had low predictive accuracy for mortality, with areas under the receiver-operating-characteristics curve of 0.60 (95% CI, 0.46-0.73), 0.52 (95% CI, 0.33-0.72) and 0.57 (95% CI, 0.45-0.68) for IUD, NND and PND, respectively. There was no difference in the risk of overall IUD, single IUD, double IUD, NND or PND between pregnancies managed as an inpatient compared with those managed as an outpatient, for any BW-discordance cut-off.

CONCLUSIONS

MCMA twin pregnancies with BW discordance are at increased risk of fetal death, signaling a need for increased levels of monitoring. Despite this, the predictive accuracy for mortality is low; thus, detection of BW discordance alone should not trigger intervention, such as iatrogenic delivery. The current data do not demonstrate an advantage of inpatient over outpatient management in these cases. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Challenges for better care based on the course of maternal body mass index, weight gain and multiple outcome in twin pregnancies: a population-based retrospective cohort study in Hessen/Germany within 15 years

Introduction

Studies on maternal weight, gestational weight gain and associated outcomes in twin pregnancies are scarce. Therefore, we analyzed these items in a large cohort.

Methods

Data from 10,603/13,725 total twin pregnancies from the perinatal database in Hessen, Germany between 2000 and 2015 were used after exclusion of incomplete or non-plausible data sets. The course of maternal and perinatal outcomes was evaluated by linear and logistic regression models.

Results

The rate of twin pregnancies increased from 1.5 to 1.9% (p < 0.00001). Mean maternal age and pre-pregnancy weight rose from 31.4 to 32.9 years and from 68.2 to 71.2 kg, respectively (p < 0.001). The rates of women with a body mass index ≥ 30 kg/m² increased from 11.9 to 16.9% with a mean of 24.4–25.4 kg/m² (p < 0.001). The overall increase of maternal weight/week was 568 g, the 25th quartile was 419, the 75th quartile 692 g/week. The total and secondary caesareans increased from 68.6 to 73.3% and from 20.6 to 39.8%, respectively (p < 0.001). Rates of birthweight < 1500 g and of preterm birth < 28 and from 28 to 33 + 6 weeks all increased (p < 0.01). No significant changes were observed in the rates of stillbirth, perinatal mortality and NICU admissions.

Conclusion

The global trend of the obesity epidemic is equally observed in German twin pregnancies. The increase of mean maternal weight and the calculated quartiles specific for twin pregnancies help to identify inadequate weight gain in twin gestations. Policy makers should be aware of future health risks specified for singleton and twin gestations.

Prevalence, antenatal management and perinatal outcome of monochorionic monoamniotic twin pregnancy: a collaborative multicenter study in England, 2000-2013

OBJECTIVES

To determine the prevalence of monochorionic monoamniotic (MCMA) twin pregnancy and to describe perinatal outcome and clinical management of these pregnancies.

METHODS

In this multicenter cohort study, the prevalence of MCMA twinning was estimated using population-based data on MCMA twin pregnancies, collected between 2000 and 2013 from 11 Northern Survey of Twin and Multiple Pregnancy (NorSTAMP) maternity units. Pregnancy outcome at < 24 weeks' gestation, antenatal parameters and perinatal outcome (from ≥ 24 weeks to the first 28 days of age) were analyzed using combined data on pregnancies confirmed to be MCMA from NorSTAMP and the Southwest Thames Region of London Obstetric Research Collaborative (STORK) multiple pregnancy cohort for 2000-2013.

RESULTS

The estimated total prevalence of MCMA twin pregnancies in the North of England region was 8.2 per 1000 twin pregnancies (59/7170), and the birth prevalence was 0.08 per 1000 pregnancies overall (singleton and multiple). Using combined data from NorSTAMP and STORK, the rate of fetal death (at < 24 weeks' gestation), including terminations of pregnancy and selective feticide, was 31.8% (54/170); the overall perinatal mortality rate was 14.7% (17/116), ranging from 69.2% at < 30 weeks to 4.5% at ≥ 33 weeks' gestation. MCMA twins that survived in utero beyond 24 weeks were delivered, usually by Cesarean section, at a median of 33 (interquartile range, 32-34) weeks of gestation.

CONCLUSIONS

In MCMA twins surviving beyond 24 weeks of gestation, there was a higher survival rate compared with in previous decades, presumably due to early diagnosis, close surveillance and elective birth around 32-34 weeks of gestation. High perinatal mortality at early gestations was attributed mainly to extreme prematurity due to preterm spontaneous labor. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Health professionals' perspectives on bereavement following loss from a twin pregnancy: a qualitative study

OBJECTIVE

To provide an in-depth understanding of the perspectives of health professionals caring for parents who have lost a baby from a twin pregnancy, either during pregnancy or in the neonatal period.

STUDY DESIGN

A qualitative study involving semi-structured interviews. Twenty-six health professionals were interviewed from maternity and neonatal departments in one hospital. Data were analyzed using a generative thematic approach.

RESULTS

Three main themes were identified from the data: health professionals' lack of confidence in their interactions with bereaved parents; their desire to learn more about bereavement; and a consideration of sensitive health-care practices for bereaved parents.

CONCLUSIONS

Health professionals acknowledged that parents who experience the loss of a twin have specific needs, some of which can be addressed by relatively small changes to clinical practices and behaviors. They felt, however, that they needed education about bereavement in order to react more effectively to bereaved parents' needs.

Pregestational diabetes is associated with adverse outcomes in twin pregnancies: a regional register-based study

INTRODUCTION

The incidence of pregnancies complicated by twinning and diabetes is increasing in the UK. This is a worrying trend as both diabetes and twin gestations are associated with a high risk of adverse pregnancy outcomes. The few studies that have specifically addressed how twinning and pregestational diabetes in the same pregnancy may affect outcome have reported conflicting results.

MATERIAL AND METHODS

We analyzed data on 27 women with a twin pregnancy and pregestational diabetes (54 babies) and 6407 women with a twin pregnancy without diabetes (12 814 babies) from the Northern Survey of Twin and Multiple Pregnancy during 1998-2010. A composite adverse pregnancy outcome (comprising fetal loss before 24 weeks, termination of pregnancy, stillbirth, infant death or any major congenital anomaly), extended perinatal mortality (stillbirths and neonatal deaths) and major congenital anomaly were the main outcome measures. Adjusted rate ratios were estimated using generalized estimating equations for Poisson regression controlling for potential confounders.

RESULTS

Mothers with twin pregnancies with diabetes were older (p = 0.001) and had higher body mass indices (p < 0.0001) than those without diabetes. Their twins were more likely to be delivered earlier (p = 0.026), be delivered by cesarean section (80.4% vs. 49.7%; p < 0.0001), be large-for-gestational-age (p < 0.0001) and require admission to a special care baby unit (p < 0.0001). Pregestational diabetes was associated with significantly increased rates of the composite adverse outcome and major congenital anomalies in twins (adjusted rate ratios 2.66, 95% confidence interval 1.14-6.20 and adjusted rate ratios 3.51, 95% confidence interval 1.31-9.40, respectively).

CONCLUSION

Maternal pregestational diabetes in twin pregnancies is associated with a significantly increased risk of an adverse pregnancy outcome.

Increased risk of congenital heart disease in twins in the North of England between 1998 and 2010

Objective

To examine the relative risk (RR) of congenital heart disease (CHD) in twins compared with singletons, according to chorionicity.

Methods

Twins and singletons with CHD notified to the Northern Congenital Abnormality Survey between 1998 and 2010 were included in this population-based study. Information on chorionicity was obtained from the Northern Survey of Twins and Multiple Pregnancy. Prevalence was calculated as the number of cases occurring in live births, late miscarriages (20–23 weeks), stillbirths (≥24 weeks) and terminations of pregnancy for fetal anomaly, per 10 000 total births. The risk of CHD in twins compared with singletons was estimated using Poisson regression.

Results

There were 399 414 singleton births of which 2984 (0.7%) had CHD. Among 11 871 twin births, 154 (1.3%) had CHD; one twin was affected by CHD in 2.5% of twin pregnancies. Of 8605 dichorionic (DC) births and 2317 monochorionic (MC) births, 96 (1.1%) and 47 (2.0%) were associated with CHD. Compared with singletons, twins were at significantly increased risk of CHD (RR=1.73, 95% CI 1.48 to 2.04; p<0.001). MC twins were at 82% significantly increased risk of CHD compared with DC twins (RR=1.82, 95% CI 1.29 to 2.57; p<0.001). The RR of severe and mild CHD was particularly high in MC twins compared with singletons (292% increased risk, RR=3.92, 95% CI 1.25 to 12.30, p=0.02 and 207% increased risk, RR=3.07, 95% CI 2.20 to 4.28; p<0.001).

Conclusions

Compared with singletons, twins were at increased risk of CHD, the risk being substantially higher among MC twins. This information is important for health professionals when counselling women with twin pregnancies.

Pregnancy outcomes before and after institution of a specialised twins clinic: a retrospective cohort study

BACKGROUND

Although specialised clinics for multiple pregnancies are recommended by several Obstetrics and Gynaecology governing bodies, studies examining outcome before and after introduction of such clinics remain few, were performed predominantly in North America in the 1990s, and either amongst dichorionic twin pregnancies only or where chorionicity was not specified. Our objective, in the modern setting with twins of known chorionicity, was to compare maternal and neonatal outcomes of twin pregnancies before and after commencement of a consultant-led, multidisciplinary twins clinic (TC).

METHODS

Retrospective cohort study of 513 women, with birth of twins at ≥20 weeks' gestation, January 2007 to November 2011, at a metropolitan tertiary maternity hospital, Sydney, Australia. Demographic, pregnancy, and outcome data were obtained from hospital databases. Women receiving TC care (2009-2011) were compared to those receiving general antenatal clinic (ANC) care (2007-2010) and private care (2009-2011). Other models of care were excluded. Main outcome measures were total maternal inpatient stay, mode of birth, gestational age at birth, and neonatal nursery admission.

RESULTS

286 women were included in the main analyses: 84 attended ANC, 101 TC, and 101 a private obstetrician. TC women had similar demographics to ANC women and were slightly younger than private patients. TC women had lower Caesarean section rates (55% vs. 70% ANC and 76% private, p = 0.008) and fewer late preterm (34 + 0-36 + 6 weeks) births, (26%TC vs. 44% ANC and 41% private, p < 0.001). Median maternal inpatient stay was shorter in TC than ANC (7 vs. 8 days, p = 0.009) and similar to private (7 days). Nursery admission rates were higher in private patients (67% vs. 49% ANC and 47% TC, p = 0.001) and average birthweight lower (2283 g vs. 2501 g ANC and 2496 g TC, p < 0.001).

CONCLUSIONS

Within a single centre, maternal and neonatal twin pregnancy outcomes varied significantly by model of care. Introducing a specialised twins clinic in our setting decreased Caesarean section rates, late preterm birth, and inpatient stay compared to ANC.

Clinical factors associated with failed trials of labor in late preterm and term twin pregnancies

OBJECTIVE

To evaluate the perinatal outcomes and clinical factors of unsuccessful trials of labor (TOLs) in late preterm and term twin pregnancies.

METHODS

We enrolled 896 consecutive twin pregnancies delivered between 1999 and 2012 in a single center, which met the following inclusion criteria: a vertex first twin, live twins, and attempted TOLs after 34 weeks. Obstetric characteristics and perinatal outcomes were compared between vaginal delivery and cesarean delivery groups.

RESULTS

Successful TOLs were carried out in 81% (726/896). Failed TOLs occurred in 15% (37/247) of late preterm twins and 20% (133/649) of term twins. Comparisons of neonatal outcomes between the groups showed no significant differences in NICU admission, ventilator use, and composite morbidity. On univariable analysis, nulliparity, preeclampsia, induced labor, excessive weight gain, and intertwin weight discordance of >30% showed significant associations with failed TOLs. Multivariable analyses revealed nulliparity (adjusted odds ratio 9.89, 95% confidence interval 4.64-21.1) and preeclampsia (adjusted odds ratio 2.17, 95% confidence interval 1.30-3.63) as significantly associated with failed TOLs.

CONCLUSION

In late preterm and term twins, trials of labor can be performed successfully without a significant increase in adverse neonatal outcomes. Nulliparity and preeclampsia are clinical factors associated with failed TOLs in twin pregnancies.

Effect of advanced maternal age on perinatal outcomes in twins: the impact of chorionicity

PURPOSE

In contrast to singletons, twins born to older mothers have lower rates of perinatal mortality than twins born to younger mothers. We examined whether differences in chorionicity could explain this unexpected maternal age effect.

METHODS

We used population-based data on twins born to mothers aged 20-29 (n = 3702) and ≥35 years (n = 1880) in the North of England, UK, 1998-2007. We calculated rate ratios (RR) and 95% confidence intervals (CIs) to estimate the effect of maternal age; adjusted RRs (ARRs) were estimated by the use of generalized estimating equations for Poisson regression controlling for chorionicity and other confounders.

RESULTS

Older mothers had a lower proportion of monochorionic twins (17.6% vs. 24.3%, P < .01); lower neonatal (RR, 0.57; 95% CI, 0.34-0.95) and perinatal mortality (RR, 0.74; 95% CI, 0.53-1.04). Adjustment for chorionicity attenuated these associations (ARR, 0.59; 95% CI, 0.35-0.98 and ARR, 0.80; 95% CI, 0.57-1.12, respectively) and after further adjustment for additional factors, both associations became nonsignificant. Older mothers had greater rates of small-for-gestational-age infants (ARR, 1.59; 95% CI, 1.24-2.05), and cesarean delivery (ARR, 1.31; 95% CI, 1.16-1.48).

CONCLUSIONS

Perinatal death rates were lower but not statistically different for twins born to older versus younger mothers. This association was attenuated by adjustment for chorionicity.