Birthweight is an independent predictor of birth asphyxia in twins: A retrospective cross-sectional cohort study of 5337 Chinese twins

OBJECTIVE

Few studies are available on birth asphyxia risks in twin neonates. This retrospective multi-center cross-sectional study determined the birthweight percentiles of 5337twins and birth asphyxia incidence of the twin population.

METHODS

We retrieved sociodemographic and obstetric data from the electronic records systems of participating centers. Neonate birthweight was measured within 24 h of birth. Perinatal asphyxia was diagnosed if 5-minute Apgar score was ≤5, or resuscitation was required 10 min after birth. The primary outcome was the incidence of birth asphyxia.

RESULTS

Totally 5337 neonates were eligible. The mean neonatal birthweight was 2227.1 ± 608.99 g and the 5th, 50th, and 95th percentiles of birthweight were 970, 2400, and 3080 g, respectively. The mean Apgar score was 9.06 ± 1.73 at 1 min and 8.99 ± 1.74 at 5 min. Totally 13.5 % (705/5222) twins had asphyxia and 9.35 % and 4.16 % twins had moderate and severe asphyxia, respectively. Twins with a birthweight< 1500 g had the highest asphyxia rate (64.8 %) and twins with a birthweight between 2500 and 3000 g had the lowest asphyxia rate (3.6 %). Stepwise logistic regression analysis revealed that higher birthweight was associated with a significantly reduced risk of asphyxia [OR 0.772 (95 %CI 0.755, 0.789), P < 0.001]. The AUROC for mean twin birthweight was 0.86±0.01 (95 %CI 0.84, 0.88) using a cutoff of 1950 g, with a sensitivity of 0.84 and a specificity of 0.78.

CONCLUSION

Twins have lower birthweight versus singletons and a significant proportion of twins, especially twins with lower birthweight, are at risk of birth asphyxia. Birthweight is an independent predictor of asphyxia and should be further explored as a predictive marker for stratifying asphyxia risks in twin neonates.

The effect of blastocyst transfer on newborn sex ratio and monozygotic twinning rate: an updated systematic review and meta-analysis

RESEARCH QUESTION

Is blastocyst transfer (BT) associated with a higher offspring secondary sex ratio and monozygotic twinning (MZT)?

DESIGN

A systematic search of PubMed/MEDLINE, Embase, Web of Science, Cochrane Library and Google Scholar databases was carried out for studies published between 1995 and May 2017 using relevant keywords and a meta-analysis performed on selected studies. The analysis was performed using Stata 12.0; odds ratios (OR) and 95% confidence intervals (CI) were used to assess the results for binary studies. Subgroup analyses and meta-regression were also conducted.

RESULTS

Twenty-six studies published between 2001 and May 2017 (sex ratio: 13, MZT: 12, and both sex ratio and MZT: 1) were identified. The analysis showed a significantly higher M/F ratio at birth (OR = 0.89, 95% CI: 0.86 to 0.93, I² = 19.8%) and a higher risk of MZT (OR = 0.37, 95% CI: 0.22 to 0.60, I² = 75.2%) after BT compared with cleavage-stage embryo transfer (CT). Furthermore, a subgroup analysis was performed based on studies published after 2009; results were found to be consistent with the 2009 meta-analysis.

CONCLUSIONS

This meta-analysis provides an update and stronger evidence to support the observation that BT is associated with a higher proportion of males and an increased risk of MZT. In clinical practice, these BT-associated neonatal outcomes should be taken into account when counselling infertility patients.

Outcome of monochorionic-biamniotic twins conceived by assisted reproduction: a population-based study

Objecive: To evaluate the perinatal outcome of monochorionic-diamniotic twins conceived by assisted reproduction technology (ART).

METHODS

We compared data from a national population-based perinatal registry on perinatal outcomes of monochorionic-diamniotic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic-diamniotic twins. We compared maternal characteristics, pregnancy complications and perinatal outcomes.

RESULTS

Monochorionic-diamniotic twin pregnancies (n=45) comprised 5.5% of all ART twins, and 9.3% of all monochorionic twins in this dataset. ART does not appear to increase the already high risk of monochorionicity compared to spontaneous conception, with the latter having an increased incidence for birth weight <1500 g [odds ratio (OD) 2.6, 95% confidence interval (CI) 1.2-5.4].

CONCLUSION

Our results disagree with hospital-based data and suggest that monochorionic-diamniotic twins following ART are not at increased risk of adverse perinatal outcomes compared to spontaneous monochorionic-diamniotic twins as well as to dichorionc twins conceived by ART.

Clinical outcomes after assisted reproductive technology in twin pregnancies: chorionicity-based comparison

The chorionicity–based evaluation of the perinatal risk in twin pregnancies after assisted reproductive technology (ART) is lacking. A retrospective review was performed of all twin pregnancies monitored prenatally and delivered at our hospital between 2010 and 2014. Chorionicity was diagnosed by ultrasound examination at first trimester and confirmed by postnatal pathology. Pregnancy and perinatal outcomes were prospectively recorded. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated in a logistic regression model. A total of 1153 twin pregnancies were analyzed. The occurrence of preterm premature rupture of membranes (PPROM) was 3 times as frequent in monochorionic diamniotic (MCDA) twin pregnancies after ART as in those spontaneous counterparts (aOR 3.0; 95%CI 1.1–3.2). The prevalence of intrahepatic cholestasis of pregnancies (ICP) was significantly higher in dichorionic diamniotic (DCDA) twin pregnancies following ART compared to spontaneous DCDA pregnancies (aOR 3.3; 95%CI 1.3–5.6). Perinatal outcomes did not differ between two conception methods, either in MCDA or DCDA twin pregnancies. Based on differentiation of chorionicity, ART is associated with the increased risk of PPROM in MCDA twin pregnancies and with a higher rate of ICP in DCDA twin gestations. ART does not increase adversity of perinatal outcomes in twin pregnancies.

Early prediction of spontaneous twin very preterm birth: a population based study 2002-2012

OBJECTIVE

The aim of this study was to establish early pregnancy risk indicators for spontaneous twin very preterm birth.

METHODS

We conducted a retrospective observational population-based study. Twenty-one potential early pregnancy risk factors were analyzed using multivariable logistic regression to determine which of them was independently associated with spontaneous twin very preterm birth.

RESULTS

Of 1815 spontaneous twin births 15.3% (277) occurred before 32 weeks. Previous preterm delivery (aOR 3.73; 95% CI, 2.52-5.52), nulliparity (aOR 2.94; 95% CI, 2.09-4.14), body mass index <18.5 (aOR 1.86; 95% CI, 1.12-3.10), body mass index ≥30 (aOR 1.87; 95% CI, 1.21-2.89), hysteroscopic metroplasty (aOR 1.63; 1.07-2.49), conization (aOR 2.05; 95% CI, 1.07-3.94) and monochorionicity (aOR 1.83; 95% CI, 1.28-2.63) were significantly associated with twin very preterm birth.

CONCLUSIONS

Pending verification in other populations, twin pregnancies at significant risk for spontaneous very preterm birth can be identified in early pregnancy using several risk indicators.

Impact of prematurity on language skills at school age

PURPOSE

The existing literature on language outcomes in children born prematurely focuses almost exclusively on standardized test scores rather than discourse-level abilities. The authors of this study looked longitudinally at school-age language outcomes and potential moderating variables for a group of twins born prematurely versus a control group of twins born at full term, analyzing both standardized test results and language sample data from the population-based Western Reserve Reading Project (WRRP; Petrill, Deater-Deckard, Thompson, DeThorne, & Schatschneider, 2006).

METHOD

Fifty-seven children born prematurely, at ≤32 weeks or <1,500 g, were compared with 57 children born at full term and were matched for age, gender, race, and parental education. Data included discourse-level language samples and standardized test results, collected at average ages 7, 8, and 10 years. The language samples were analyzed to yield a number of semantic and syntactic measures that were consolidated via factor analysis.

RESULTS

Regression models showed significant differences between the 2 groups for standardized test results, although the mean score for both groups fell in the normal range. For the discourse-level language measures, however, differences never reached statistical significance. Parental education was significantly associated with improved standardized test scores.

CONCLUSIONS

These findings suggest that in the absence of frank neurological impairment, sophisticated semantic and syntactic skills may be relatively intact in the discourse-level language of children born prematurely. Implications for assessment, particularly the potential role of attention and executive function in standardized testing tasks, are reviewed.

Effect of parity on gestational age at delivery in multiple gestation pregnancies

OBJECTIVE

To estimate the effect of parity on gestational age (GA) at birth in multifetal pregnancies.

STUDY DESIGN

Birth data from the public-access Matched Multiple Birth File produced by the National Center for Health Statistics from 1995 to 2000 were analyzed following IRB approval. GA, parity and demographic data were analyzed with parametric and nonparametric tests, including regression analysis, using SPSS.

RESULT

Data from women with twin (n=316,983), triplet (n=11,981), and quadruplet (n=766) pregnancies were analyzed. A significantly higher proportion of nulliparous versus parous women were Caucasian (twins: 82 versus 77%; triplets: 91 versus 87%) and had more than 15 years of education (twins: 39 versus 24%; triplets: 55 versus 39%; quadruplets: 53 versus 35%). Mean GA was 5.6 days longer for twins, 5.4 days longer for triplets and 6.8 days longer for quadruplets born to parous versus nulliparous women. Caucasian and African-American parous women pregnant with twins or triplets delivered their babies at a later GA than their nulliparous counterparts at each level of education. GA at delivery increased as a function of age of the mother in nulliparous and parous women of twins or triplets, and at every age level, parous women delivered their babies at a later GA. A higher proportion of nulliparous women delivered before 24 weeks (twins: 2.9 versus 1.2%; triplets: 5.9 versus 2.5%; quadruplets: 8.3 versus 2.6%). The percentage of twins born at or after 32 weeks was 84.9% for nullipara and 90.1% for parous women; for triplets, corresponding figures were 61.4 and 69.6%; and for quadruplets the figures were 33.2 and 44.2%. The percentage of births at or after 36 weeks for nulliparous and parous women pregnant with twins was 54.8 and 63.2%, respectively. The majority of the gain in GA was observed between women who had no previous births and those who had one previous birth. In regression analysis, the effect of parity remained after controlling for demographic and risk factors known to affect GA.

CONCLUSION

GA at delivery is significantly increased in parous women carrying a multifetal gestation after controlling for other factors that affect GA at birth.

Impact of blastocyst transfer on offspring sex ratio and the monozygotic twinning rate: a systematic review and meta-analysis

OBJECTIVE

To determine the sex ratio and risk of monozygotic twinning (MZT) after blastocyst transfer compared with cleavage-stage embryo transfer (ET) in fresh IVF cycles.

DESIGN

Systematic review and meta-analysis.

SETTING

University hospital center for reproductive medicine and IVF.

PATIENT(S)

Results of all reports from January 1995 to November 2007 with women undergoing nondonor fresh IVF. The sex ratio of 2,587 offspring and MZT rate in 40,917 cycles were included.

INTERVENTION(S)

Cleavage or blastocyst stage for embryo transfer.

MAIN OUTCOME MEASURE(S)

Sex ratio and rate of MZT.

RESULT(S)

A meta-analysis was performed using four studies for sex ratio and nine studies for MZT. The results of the meta-analysis using a fixed effect model demonstrated a higher male-female ratio after blastocyst transfer compared with cleavage-stage ET (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.10-1.51), and this difference was statistically significant. The risk of MZT after blastocyst transfer was significantly higher compared with cleavage-stage ET (OR 3.04, 95% CI 1.54-6.01).

CONCLUSION(S)

The combined data presented in this meta-analysis suggest that blastocyst transfer appears to be associated with a sex ratio skewed in favor of males and an increased risk of MZT. The clinicians should provide this information to their infertility patients awaiting blastocyst transfer.

Neonatal outcome in preterm monochorionic twins with twin-to-twin transfusion syndrome after intrauterine treatment with amnioreduction or fetoscopic laser surgery: comparison with dichorionic twins

OBJECTIVE

The purpose of this study was to compare neonatal outcome in preterm neonates after twin-to-twin transfusion syndrome (TTTS) that was treated by amnioreduction or fetoscopic laser surgery (FLS) and in dichorionic neonates who were matched for gestational age at birth.

STUDY DESIGN

Neonatal outcome was assessed in 137 TTTS preterm neonates who were treated primarily with either amnioreduction (n = 36) or FLS (n = 101) and compared with dichorionic twins (n = 242) who were delivered at our center at 24-34 weeks of gestation.

RESULTS

Adverse neonatal outcome (death or severe cerebral lesions) was more frequent in the amnioreduction group than in the FLS and dichorionic groups. Overall neonatal outcome was comparable in FLS and dichorionic infants. However, neonatal morbidity was higher in FLS neonates at <30 weeks of gestation that was related mainly to failed laser therapy.

CONCLUSION

In preterm TTTS cases, neonatal morbidity decreases independently with gestational age and after successful FLS. Neonatal morbidity that was specific of TTTS was higher in the amnioreduction group and in cases with failed laser therapy.

Prospective risk of intrauterine death of monochorionic-diamniotic twins

OBJECTIVE

The purpose of this study was to calculate the prospective risk of fetal death in monochorionic-diamniotic twins.

STUDY DESIGN

We evaluated 193 monochorionic diamniotic twin pregnancies that were followed and delivered after 24 weeks. Surveillance included cardiotocography and sonography performed at least once weekly. The prospective risk of fetal death was calculated as the total number of deaths at the beginning of the gestational period divided by the number of continuing pregnancies at or beyond that period.

RESULTS

The fetal death rate was 5 of 193 pregnancies (2.6%; 95% CI, 1.1, 5.9); the prospective risk of stillbirth per pregnancy after 32 weeks of gestation was 1.2% (95% CI, 0.3% - 4.2%).

CONCLUSION

Under intensive surveillance, the prospective risk of fetal death in monochorionic-diamniotic pregnancies after 32 weeks of gestation is much lower than reported and does not support a policy of elective preterm delivery.

Persistance of adverse obstetric and neonatal outcomes in monochorionic twins after exclusion of disorders unique to monochorionic placentation

OBJECTIVE

This study was undertaken to assess obstetric and neonatal outcomes in dichorionic twins and monochorionic-diamniotic twins after exclusion of twin-to-twin transfusion syndrome and twin reversed arterial perfusion sequence.

STUDY DESIGN

Data from a tertiary center were collected in twin gestations between 1994 and 2002. Chorionicity was defined by standard echographic criteria and placental examination at delivery. Neonatal outcomes were compared between monochorionic and dichorionic gestations.

RESULTS

This study included 503 women: 378 (75%) dichorionic and 125 (25%) monochorionic twin gestations. Monochorionic twin gestations had a higher risk of preterm deliveries between 30 and 34 weeks' gestation than pregnancies with dichorionic twins (P < .01). Monochorionic twins had a higher number of birth weight less than 10th percentile (P < .001) discordancy 25% or greater (P < .02), admission to neonatal intensive care unit (P < .03), and intraventricular hemorrhage grade 3 and 4 (P < .007) than dichorionic twins even after adjusting for gestational age.

CONCLUSION

Monochorionic diamniotic twins have a higher risk of perinatal complications than dichorionic twin gestations, even after exclusion of disorders unique to monochorionic placentation.

Monochorionic twin pregnancies

The monochorionic placenta should be considered a developmental malformation and, as such, represents one of the most common birth defects. Great strides are being made to unravel the progression of nature's successful attempt at human cloning through fission. Critical to any strategy to reduce the perinatal morbidity and mortality associated with monochorionic placentas is early detection. Intense surveillance in at risk pregnancies will provide a better understanding of their natural progression, improve the prognosis with early intervention, and ultimately provide the key to prevent many of the complications unique to the monochorionic placenta.

High risk of unexpected late fetal death in monochorionic twins despite intensive ultrasound surveillance: a cohort study

BACKGROUND

The rationale for fetal surveillance in monochorionic twin pregnancies is timely intervention to prevent the increased fetal/perinatal morbidity and mortality attributed to twin-twin transfusion syndrome and intrauterine growth restriction. We investigated the residual risk of fetal death after viability in otherwise uncomplicated monochorionic diamniotic twin pregnancies.

METHODS AND FINDINGS

We searched an electronic database of 480 completed monochorionic pregnancies that underwent fortnightly ultrasound surveillance in our tertiary referral fetal medicine service between 1992 and 2004. After excluding pregnancies with twin-twin transfusion syndrome, growth restriction, structural abnormalities, or twin reversed arterial perfusion sequence, and monoamniotic and high-order multiple pregnancies, we identified 151 uncomplicated monochorionic diamniotic twin pregnancies with normal growth, normal liquor volume, and normal Doppler studies on fortnightly ultrasound scans. Ten unexpected intrauterine deaths occurred in seven (4.6%) of 151 previously uncomplicated monochorionic diamniotic pregnancies, within 2 wk of a normal scan, at a median gestational age of 34(+1) wk (weeks(+days); range 28(+0) to 36(+3)). Two of the five cases that underwent autopsy had features suggestive of acute late onset twin-twin transfusion syndrome, but no antenatal indicators of transfusional imbalance or growth restriction, either empirically or in a 1:3 gestation-matched case-control comparison. The prospective risk of unexpected antepartum stillbirth after 32 wk was 1/23 monochorionic diamniotic pregnancies (95% confidence interval 1/11 to 1/63).

CONCLUSION

Despite intensive fetal surveillance, structurally normal monochorionic diamniotic twin pregnancies without TTTS or IUGR are complicated by a high rate of unexpected intrauterine death. This prospective risk of fetal death in otherwise uncomplicated monochorionic diamniotic pregnancies after 32 wk of gestation might be obviated by a policy of elective preterm delivery, which now warrants evaluation.

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.

Evidence-based care of women with a multiple pregnancy

Women with a multiple pregnancy face greater risks for themselves and their infants than women pregnant with one child. Pre-pregnancy care should focus on avoiding multiple pregnancy. Early prenatal care centres on determining chorionicity and screening for fetal anomalies, with later care focusing on the presentation, prediction and management of preterm birth, and intrauterine growth restriction. The optimal timing and mode of birth are the focus of current multicentre, randomised, controlled trials. However, the data from such trials on care for women with a multiple pregnancy are limited. Many areas of care require better-quality information, including when using assisted reproductive techniques, the optimal number of embryos to be transferred, care after the diagnosis of chorionicity, and the benefits of specialised multiple pregnancy clinics. Better-quality information is required to inform clinical practice for women with complications of multiple pregnancy, including monoamniotic twin pregnancy, treatment of twin-to-twin transfusion syndrome, and care following single intrauterine fetal death.

Discordant growth in twins

Discordant growth in twins contributes significantly to rates of perinatal morbidity and mortality. These rates vary according to chorionicity, timing of onset and severity. We have reviewed English language literature in Medline since 1980. It is clear that diagnosis of discordant growth has improved due to the use of serial ultrasound examination. Following the detection of differences in fetal size, diagnosis is facilitated by umbilical artery and fetal Doppler studies. Management options vary according to chorionicity, timing of onset and umbilical-fetal Doppler studies. The mode of delivery in discordant twins remains controversial. We conclude that ultrasound surveillance of twin gestations, combining serial biometry and selective Doppler studies, is effective in the recognition of significant intrauterine growth restriction in co-twins. Differences in etiology and management underscore the importance of establishing chorionicity routinely as soon as twin gestation is diagnosed.

Why is it important to diagnose chorionicity and how do we do it?

Because the monochorionic (MC) placenta is designed for a singleton fetus, and might not provide adequate physiological support for twins, obstetric problems are more frequent in MC than dichorionic (DC) twins. Problems arise because asymmetric cord insertions cause growth discordance as a result of unequal sharing of placental tissue. Approximately 95% of MC twin placentas contain interfetal vascular connections of some kind, sometimes in several combinations. Such connections can cause twin-twin transfusion syndrome and twin reversed arterial perfusion. The survivor can also suffer damage if the co-twin dies spontaneously or from inappropriate methods of selective termination. These complications are progressive and often advanced by 18 weeks gestation. Monoamniotic twins carry greater risks than diamniotic twins, especially entangled cords. MC twins are often discordant for congenital anomalies. Diagnosis of MC twinning is optimal in the first trimester. Optimal management of these MC twin disorders is not yet established; long-term follow-up studies are unsatisfactory. In clinical practice, chorionicity is not always determined in the first trimester.