Gestational age at delivery and neonatal outcome in uncomplicated twin pregnancies: what is the optimal gestational age for delivery according to chorionicity?

Comparison of International Guidelines on the Management of Twin Pregnancy

OBJECTIVES

To review current international clinical guidelines on the antenatal and intrapartum management of twin pregnancies, examining areas of consensus and conflict.

METHODS

We conducted a database search using Medline, Pubmed, Scopus, Academic Search Complete, CINAHL and ERCI Guidelines website. Guidelines were screened for eligibility using our inclusion and exclusion criteria. Those deemed eligible were quality assessed using the AGREE II tool and relevant data was extracted.

RESULTS

We identified 21 relevant guidelines from 16 countries including two international society guidelines. There was consensus in determination of chorionicity and amnionicity within the first trimester, fetal anomaly scan between 18 and 22 weeks and the recommended screening for twin-to-twin transfusion syndrome (TTTS). For those that provided intrapartum guidance, there was agreement in recommending caesarean section to deliver monochorionic monoamniotic (MCMA) twins, epidural anaesthesia for intrapartum analgesia and the use of cardiotocography (CTG) for intrapartum fetal monitoring. The main areas of conflict included cervical length screening, frequency of ultrasound surveillance, timing of delivery of dichorionic twin pregnancies and circumstances for recommending vaginal delivery. There was a lack of advice on intrapartum management.

CONCLUSIONS

This review has highlighted the need for unified international guidance on the management of twin pregnancy. Comparisons of current guidance demonstrates a lack of confidence in the management of labour in twin pregnancies. Further evidence on intrapartum care of twin pregnancies is needed to inform practice guidelines and improve both short and long term maternal and fetal outcomes.

Chorionicity, birth weight discordance and neonatal morbidity in uncomplicated twin pregnancies delivered from 36 weeks

OBJECTIVES

To investigate the association between chorionicity, birth weight discordance and neonatal morbidity in uncomplicated twin pregnancies progressing to at least 36 weeks of gestation.

STUDY DESIGN

This was a retrospective single centre cohort study of all twin pregnancies referred to our twin clinic between 2011 and 2018. Outcome details were obtained from the computerized maternity and neonatal records. The primary outcome was incidence of composite neonatal morbidity according to chorionicity. We also determined the incidence of composite neonatal morbidity in pregnancies with birth weight discordance. Logistic regression was used to identify and adjust for potential confounders.

RESULTS

Three hundred and eighty-five twin pregnancies (286 dichorionic, 99 monochorionic) were included. Gestational age at birth was significantly lower in pregnancies complicated by neonatal morbidity (p = 0.013) compared with those which were not. On multivariable logistic regression analysis, gestational age at birth (p = 0.031) and birth weight discordance (p = 0.004), but not chorionicity (p = 0.626) were independently associated with neonatal morbidity.

CONCLUSION(S)

In uncomplicated twin pregnancies chorionicity is not associated with neonatal morbidity. Gestational age at birth is the major determinant of neonatal outcome while the clinical impact of weight discordance seems marginally significant.

Changes in the perinatal outcomes of twin pregnancies delivered at a tertiary referral center in Korea during a 24-year period from 1995 to 2018

Objective

To analyze the changes in the clinical characteristics and perinatal outcomes of twin pregnancies delivered at a tertiary referral center in Korea during a 24-year period.

Methods

This was a retrospective cohort study of twin pregnancies delivered at 24–40 weeks of gestation, from 1995 to 2018. The subjects were divided into 4 groups according to the year of delivery: 1995–2000, 2001–2006, 2007–2012, and 2013–2018. The trends in the changes in the twin birth rate, maternal age, assisted reproductive technology (ART) pregnancy rate, chorionicity, obstetric complications, delivery outcomes, and neonatal outcomes over the periods were analyzed.

Results

A total of 2,133 twin pregnancies were included in the study. The twin birth rate increased from 16.7/1,000 in 1995–2000 to 42.2/1,000 in 2001–2006, 49.5/1,000 in 2007–2012, and 61.8/1,000 in 2013–2018. The maternal age and ART pregnancy and dichorionic twin rates increased, while the monochorionic twin rate decreased over the periods. The incidence of fetal congenital anomalies, cervical incompetence, gestational diabetes mellitus, preeclampsia, and placental abruption increased over the periods. The preterm birth (PTB) rate significantly decreased owing to the decreasing elective late-PTB rate; however, the early-PTB rate significantly increased.

Conclusion

This study found that twin pregnancies increased steadily over the last 24 years and that the increase was related to increased maternal age and ART pregnancy rate. The incidence of obstetric complications increased over the periods; however, the neonatal intensive care unit admission rate decreased, along with decreases in the elective late-PTB rate.

The impact of chorionicity and the type of twin growth on the early neonatal outcome in twin pregnancies - 20 years of experience from one tertiary perinatal center

OBJECTIVE

Twin pregnancies are associated with higher neonatal mortality and morbidity. Growth discordance and monochorionicity are among the factors that worsen the course of pregnancy. The study aimed to assess neonatal conditions and mortality in relation to growth type and chorionicity.

MATERIALS AND METHODS

Data from 820 pregnant women with twin pregnancies and their 1640 newborns were analyzed. The Apgar score and umbilical artery blood pH, as well as the rate of complications, were compared between dichorionic diamniotic (DCDA) and monochorionic diamniotic (MCDA) twins with symmetric and discordant growth. The Student's t-test and the Pearson chi-square test were used for comparisons.

RESULTS

There were 576 (70.2%) DCDA pregnancies, including 421 (73.1%) with symmetric growth and 155 (26.9%) with discordant growth, and 244 (29.8%) MCDA pregnancies, including 110 (45.1%) with symmetric growth and 134 (54.9%) with discordant growth. A significantly greater percentage of twins with discordant growth occurred in women older than 34 years than in those that were younger. An Apgar score of ≤7 was significantly more common among MCDA discordant twins, while an arterial umbilical blood pH of <7.2 was more common among MCDA twins with symmetric growth. Early neonatal deaths (n = 29; 1.8%), respiratory disorders, and a birth weight of <1500 g were significantly more common in MCDA twins than in DCDA twins.

CONCLUSION

MCDA twins with growth discordance are burdened with a higher risk of neonatal morbidity and mortality than symmetric DCDA twins. Chorionicity and growth discordancy are important determinants of the outcome of twin pregnancy.

The effects of birth order on neonatal outcomes in early-preterm, late-preterm and term twin infants

Objectives: Birth order is one of the main factors that influences the neonatal outcome of twins. However, there is little prior data regarding the effect of birth order under different clinical circumstances. This study investigates the effect of birth order on the neonatal outcomes of twins delivered during early-preterm, late-preterm and term gestations according to chorionicity, delivery mode and indication for delivery.Methods: This is a retrospective cohort study of women with twin pregnancies delivered at 24-40 weeks of gestation between 1995 and 2014. We excluded twin pregnancies with the following complications: twin-to-twin transfusion syndrome, monoamnionic twins, delayed interval delivery and fetal death, chromosomal anomalies or major congenital malformation in one or more of the twins. The neonatal outcomes, including death, admission to neonatal intensive care unit (NICU), mechanical ventilator support, and respiratory distress syndrome (RDS) was compared between the first and second twin born at early-preterm (24-33 weeks of gestation), late-preterm (34-36 weeks of gestation) and term (≥37 weeks of gestation) gestations. These outcomes were further analyzed according to chorionicity, mode of delivery and indication for delivery by multivariable analysis (after adjusting for sex, presentation, and birth weight).Results: Among a total of 1,614 women with twin pregnancies who met the selection criteria, 423, 674 and 517 women delivered at early-preterm, late-preterm and term gestation, respectively. Overall, the second-born twins were lighter and had higher rates of NICU admission, mechanical ventilator support, and RDS than did first-born twins. Second twins born at early-preterm gestation had higher rates of RDS and mechanical ventilator support than did first twins. Second twins born at late-preterm gestation had higher rates of NICU admission and mechanical ventilator support than did first twins. Second twins born at term gestation also had a higher NICU admission rate than did first twins. However, in the multivariable analysis of the subgroups, the rates of NICU admission, mechanical ventilator support and RDS were not significantly different between most twin pairs. However, there were several significant differences. There was a higher risk of RDS in the second twins in the early-preterm premature rupture of membranes (PROM) subgroup, and a higher risk of mechanical ventilator support in the late-preterm PROM subgroup. Low birth weight was the only significant factor independently associated with a higher risk of adverse neonatal outcome in the second twins compared with the first twins in all subgroups.Conclusions: Second twins born at early-preterm, late-preterm and term were at higher risk of adverse neonatal outcome than were their respective first twins. However, this finding was mainly represented lower birth weight of the second twin. Still, second twins delivered due to early-preterm and late-preterm PROM had a higher risk of RDS and mechanical ventilator support, respectively, than did the first twin after adjusting for birth weight.

Optimal Timing of Delivery Based on the Risk of Stillbirth and Infant Death Associated with Each Additional Week of Expectant Management in Multiple Pregnancies: a National Cohort Study of Koreans

BACKGROUND

The purpose of this study was to compare the fetal/infant mortality risk associated with each additional week of expectant management to that associated with immediate delivery in women with multiple gestations.

METHODS

This was a retrospective national cohort study of 94,170 multiple deliveries, 92,619 (98.4%) twin and 1,352 (1.44%) triplet pregnancies, between 32 0/7 and 42 6/7 weeks of gestation recorded in the Korean vital statistics database. We investigated the risks of stillbirth and infant death after birth in Korea according to the week of gestation in twin and triplet pregnancies.

RESULTS

The risk of stillbirth significantly increased between 34 and 35 weeks of gestation and between 37 and 38 weeks of gestation in twin pregnancies and between 34 and 37 weeks of gestation in triplet pregnancies. The risk of infant death following delivery gradually decreased as pregnancies approached full term. Week-by-week differences were statistically significant between 33 and 34 weeks, with decreasing risks of infant death at advancing gestational ages in twin pregnancies. At 37 weeks of gestation, the relative risk of mortality was significantly higher with expectant management compared with immediate delivery (relative risk, 3.00; 95% confidence interval, 1.41-6.38).

CONCLUSION

In twin pregnancies, delivery at 37 weeks of gestation can minimize the risks of stillbirth and infant death in uncomplicated cases, although individual maternal and fetal characteristics must be considered when determining the optimal timing of delivery. In multiple pregnancies, close fetal surveillance is needed after 34 weeks of gestation.

Comparison of perinatal outcomes in late preterm birth between singleton and twin pregnancies

Objective

To determine whether late preterm twin neonates have a more favorable perinatal outcome than singleton late preterm neonates.

Methods

We studied 401 late preterm births between 34+0 and 36+6 weeks of gestation, from January 2011 to December 2014 in our institution. We compared the maternal and neonatal characteristics and perinatal outcomes between singleton and twin pregnancies. Perinatal outcomes included Apgar score, admission to the neonatal intensive care unit (NICU) or special care nursery, duration of NICU stay, and the rate of composite morbidity (antibiotic use, hypoglycemia, hypocalcemia, hyperbilirubinemia requiring phototherapy, respiratory support, and respiratory distress syndrome).

Results

A total of 289 neonates were in the singleton group and 112 in the twin group. The twin group showed smaller mean birth weight despite of longer gestational age at delivery. In addition, there were significant differences in the indication of delivery and cesarean section rate between the 2 groups. Overall, the risk of composite morbidity was similar between 2 groups (odds ratio, 1.4; 95% confidence interval, 0.8 to 2.4).

Conclusion

Our findings suggest that late preterm twins do not show a more favorable outcome than singleton late preterm births.