How and why are triplets disadvantaged compared to twins?

Perinatal outcome and long-term hospitalization of triplets according to birth order

PURPOSE

The association between birth order and adverse perinatal outcomes has been well studied in twin pregnancies. However, little is known about the differences in immediate perinatal outcomes as well as long-term hospitalization of the offspring in triplet pregnancies according to their birth order. As such, we aimed to assess the differences in immediate perinatal outcomes and long-term hospitalizations among triplets by their birth order.

METHODS

In a retrospective hospital-based cohort study, immediate perinatal outcomes and long-term hospitalizations were compared among triplet siblings according to their birth order. Deliveries occurred between the years 1991 and 2021 in a tertiary medical center. The study groups were followed until 18 years of age for cardiovascular, respiratory, neurological, and infection-related hospitalizations. Generalized estimation equation (GEE) models were used to control for confounders. Kaplan-Meier survival curves were used to compare cumulative long-term hospitalization incidences and Cox proportional hazards models were performed to control for confounders.

RESULTS

The study included 117 triplet deliveries. Rates of small for gestational age (SGA) infants increased linearly by birth order (6.0%, 7.7%, and 15.4% for the first, second, and third siblings, respectively; p-value for trends = 0.035). Using a GEE model controlling for maternal age, being born third in a triplet pregnancy was independently associated with SGA (third vs. first sibling, adjusted OR 3.0, 95% CI 1.38-6.59, p = 0.005). No significant differences in cardiovascular, respiratory, neurological, and infection-related hospitalizations were noted among the first, second, and third siblings. Likewise, using Kaplan-Meier survival analyses, no significant differences in the cumulative incidence of long-term pediatric hospitalizations were noted between the siblings. In Cox proportional hazards models, controlling for weight and gender, birth order in a triplet pregnancy did not exhibit an association with long-term hospitalizations of the offspring.

CONCLUSION

Despite the association between birth order and SGA, birth order in triplets does not seem to have an impact on the risk for long-term offspring hospitalization.

Survey on the incidence of multiple pregnancies and neonatal outcomes by fertility treatment in Tokushima Prefecture, Japan

A survey on the incidence of multiple pregnancies and neonatal outcomes by assisted reproductive technology (ART) and non-ART fertility treatments was performed in 2011 and 2021. Questionnaires were sent to all institutions with obstetrics and gynecology departments in Tokushima Prefecture, Japan, to collect data on fertility treatments and neonatal outcomes in 2011 and 2021. Non-ART fertility treatments were classified into ovarian stimulation (treatments for cases without ovulation disorder) and ovulation induction (treatments for cases with ovulation disorder). Among all pregnancies, the multiple pregnancy rates in 2011 were 7.7% for ovarian stimulation, 5.5% for ovulation induction, and 8.4% for ART, whereas those in 2021 were 3.8%, 2.3%, and 1.9%, respectively. The rates of triplet pregnancies in 2011 were 0.85% for ovulation induction, 2.4% for ovulation induction, and 1.4% for ART, whereas those in 2021 were 0% for all treatments. The rates of low birth weight, admission to a neonatal intensive care unit, and neonatal death in 2011 were 53.8%, 9.61%, and 9.61%, respectively, whereas those in 2021 were 40.9%, 22.7%, and 0%, respectively. These findings indicate that rates of multiple pregnancies, including higher-order multiple pregnancies, by fertility treatment have decreased over the last 10 years in Tokushima Prefecture. However, some adverse neonatal outcomes have still occurred. J. Med. Invest. 71 : 251-253, August, 2024.

Pregnancy outcomes of dichorionic triamniotic triplet pregnancies after in vitro fertilization-embryo transfer: multifoetal pregnancy reduction versus expectant management

Background

Trichorionic triplet pregnancy reduction to twin pregnancy is associated with a lower risk of preterm delivery but not with a lower risk of miscarriage. However, data on dichorionic triamniotic (DCTA) triplet pregnancy outcomes are lacking. This study aimed to compare the pregnancy outcomes of DCTA triplets conceived via in vitro fertilization-embryo transfer (IVF-ET) managed expectantly or reduced to a monochorionic (MC) singleton or monochorionic diamniotic (MCDA) twins at 11–13^+ 6 gestational weeks.

Methods

Two hundred ninety-eight patients with DCTA triplets conceived via IVF-ET between 2012 and 2016 were retrospectively analysed. DCTA triplets with three live foetuses were reduced to a MC singleton (group A) or MCDA twins (group B) or underwent expectant management (group C). Each multifoetal pregnancy reduction (MFPR) was performed at 11–13^+ 6 gestational weeks. Pregnancy outcomes in the 3 groups were compared.

Results

Eighty-four DCTA pregnancies were reduced to MC singleton pregnancies, 149 were reduced to MCDA pregnancies, and 65 were managed expectantly.

There were no significant differences among groups A, B, and C in miscarriage rate (8.3 vs. 7.4 vs. 10.8%, respectively) and live birth rate (90.5 vs. 85.2 vs. 83.1%, respectively) (P > 0.05).

Group A had significantly lower rates of preterm birth (8.3 vs. 84.6%; odds ratio (OR) 0.017, 95% confidence interval (CI) 0.006–0.046) and low birth weight (LBW; 9.2 vs. 93.2%; OR 0.007, 95% CI 0.003–0.020) than group C (P < 0.001).

Group B had significantly lower preterm birth (47.0 vs. 84.6%; OR 0.161, 95% CI 0.076–0.340) and LBW rates (58.7 vs. 93.2%; OR 0.103, 95% CI 0.053–0.200) than group C (P < 0.001).

Group A had significantly lower preterm birth (8.3 vs. 47.0%; OR 0.103, 95% CI 0.044–0.237; P < 0.001), LBW (9.2 vs. 58.7%; OR 0.071, 95% CI 0.032–0.162; P < 0.001) and perinatal death rates (1.3 vs. 9.1%; OR 0.132, 95% CI 0.018–0.991; P = 0.021) than group B.

Conclusion

The MFPR of DCTA triplets to singleton or MCDA pregnancies was associated with better pregnancy outcomes compared to expectant management. DCTA triplets reduced to singleton pregnancies had better perinatal outcomes than DCTA triplets reduced to MCDA pregnancies.

Risks of miscarriage or preterm delivery in trichorionic and dichorionic triplet pregnancies with embryo reduction versus expectant management: a systematic review and meta-analysis

STUDY QUESTION

Is pregnancy outcome in triplet pregnancies improved with embryo reduction (ER) to twins compared to expectant management?

SUMMARY ANSWER

In trichorionic triplet pregnancies, ER to twins reduces the risk of preterm birth (<34 weeks) without significantly increasing the risk of miscarriage (<24 weeks), whereas in dichorionic triplet pregnancies, the results are inconclusive.

WHAT IS KNOWN ALREADY

Triplet pregnancies are associated with a high risk of miscarriage and preterm birth. ER can ameliorate these conditions in higher order multiple gestations but is still controversial in triplets.

STUDY DESIGN, SIZE, DURATION

This study aimed to conduct a systematic review, following the PRISMA guidelines, and critically appraise ER at 8-14 weeks of gestation in both trichorionic triamniotic (TCTA) and dichorionic triamniotic (DCTA) pregnancies. Selective ER to twins was compared with expectant management, focusing on the risks of miscarriage and preterm birth. The computerized database search was performed on 8 January 2017. Overall, from 25 citations of relevance, eight studies with a total of 249 DCTA and 1167 TCTA pregnancies fulfilled the inclusion criteria.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A comprehensive computerized systematic literature search of all English language studies between 2000 and 2016 was performed in PubMed, EMBASE, Scopus, Evidence Based Medicine Reviews (Cochrane Database and Cochrane Central Register of Controlled Trials) and Google Scholar. Relevant article reference lists were hand searched. The management options were compared for rates of miscarriage <24 weeks and preterm birth <34 weeks. Only studies with both expectant management and ER to twins were included in the analysis. The quality of each individual article was critically appraised and appropriate statistical methods were used to extract results.

MAIN RESULTS AND THE ROLE OF CHANCE

In TCTA pregnancies managed expectantly (n = 501), the rates of miscarriage and preterm birth were 7.4 and 50.2%, respectively. Meta-analysis demonstrated that ER to twins in TCTA pregnancies (n = 666) was associated with a lower risk (17.3 versus 50.2%) of preterm birth (RR = 0.36, 95% CI: 0.28-0.48), whereas the risk of miscarriage (8.1% versus 7.4%) did not significantly increase (RR = 1.08, 95% CI: 0.58-1.98). In DCTA triplets managed expectantly (n = 200), the rates of miscarriage and preterm birth were 8.5 and 51.9%, respectively. Although the meta-analysis was inconclusive, it suggested that ER to twins in DCTA triplets, either of the foetus with a separate placenta (n = 15) or one of the monochorionic pair (n = 34), was neither significantly associated with an increased risk of miscarriage (8.5 versus 13.3%, P = 0.628 and RR = 1.22, 95% CI: 0.38-3.95, respectively) nor with a lower risk of preterm birth (51.9 versus 46.2%, P = 0.778 and RR = 0.5, 95% CI: 0.04-5.7, respectively).

LIMITATIONS, REASONS FOR CAUTION

No randomized controlled trials of ER versus expectant management in TCTA or DCTA pregnancies were identified from our literature search. We were able to include only a handful of papers with small sample sizes and suffering from bias, and non-English publications were missed. Irrespective of the strict inclusion and exclusion criteria, publication bias was evident.

WIDER IMPLICATIONS OF THE FINDINGS

The greatest strength of our systematic review is that, contrary to the existing literature, it only included studies with both the intervention and expectant arm. Our results are in agreement with current literature. In TCTA pregnancies, ER to twins is associated with a lower risk of preterm birth but is not associated with a higher risk of miscarriage. In the absence of a randomized trial, the data from systematic reviews appear to be the best existing evidence for counselling in the first trimester on the different options available. Finally, in DCTA pregnancies, indications exist that ER (of one of the MC pair) to twins could possibly reduce the risk of preterm birth without increasing the risk of miscarriage.

STUDY FUNDING/COMPETING INTEREST(S)

None to declare.

REGISTRATION NUMBER

N/A.

Does multi-fetal pregnancy reduction adversely influence intra-uterine growth?

Multi-fetal pregnancy reduction (MFPR) is offered in the management of higher-order multiple gestations to reduce the risks associated with such pregnancies. Pregnancy outcomes, including birthweight, following MFPR have been examined with variable findings. However, little attention has been paid to in utero growth in such pregnancies. This study examines whether the intra-uterine growth performance of a twin pregnancy resulting from MFPR differs from that of an unreduced twin pregnancy. This was a retrospective analysis comparing the intrauterine growth of 20 higher order multiple pregnancies that underwent MFPR with resulting di-chorionic twin gestations with 293 unreduced di-chorionic twin gestations. Biometric nomograms were derived for the unreduced twin population and the biometric parameters for the reduced pregnancies were compared with these. There was a difference with respect to femur length in the period 20-28 weeks (p = 0.003) but no other significant differences were observed. MFPR does not itself adversely influence intra-uterine fetal growth.

Temporal trends in the frequency of twins and higher-order multiple births in Canada and the United States

BACKGROUND

The dramatic increase in multiple births is an important public health issue, since such births have elevated risks for adverse perinatal outcomes. Our objective was to explore the most recent temporal trends in rates of multiple births in Canada and the United States.

METHODS

Live birth data from Canada (excluding Ontario) and the United States from 1991-2009 were used to calculate rates of twins, and triplet and higher-order multiples (triplet+). Temporal trends were assessed using tests for linear trend and absolute and relative changes in rates.

RESULTS

Twin live births in the United States increased from 23.1 in 1991 to 32.2 per 1,000 live births in 2004, remained stable between 2004 and 2007, and then increased slightly to an all-time high of 33.2 per 1,000 live births in 2009. In Canada, rates also increased from 20.0 in 1991 to 28.3 per 1,000 live births in 2004, continued to increase modestly between 2004 and 2007, and rose to a high of 31.4 per 1,000 in 2009. Rates of triplet+ live births in the United States increased dramatically from 81.4 in 1991 to 193.5 per 100,000 live births in 1998, remained stable between 1998 and 2003 and then decreased to 148.9 per 100,000 in 2007. The rate declined marginally in 2008, but then rose again in 2009 to 153.5 per 100,000. Rates of triplet+ live births were much lower in Canada, although the temporal pattern of change was similar.

CONCLUSION

The rate of twin live births in the United States and Canada continues to increase, though more modestly than during the 1990s. Recent declines in rates of triplet+ live births in both countries have been followed by unstable trends.

Twin gestation and neurodevelopmental outcome in extremely low birth weight infants

OBJECTIVE

The purpose of this work was to compare the risk-adjusted incidence of death or neurodevelopmental impairment at 18 to 22 months' corrected age between twin and singleton extremely low birth weight infants. We hypothesized that twin gestation is independently associated with increased risk of death or adverse neurodevelopmental outcomes at 18 to 22 months' corrected age in these infants.

METHODS

We conducted a retrospective study of inborn extremely low birth weight infants admitted to Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network units between 1997 and 2005, who either died or had follow-up data available at 18 to 22 months' corrected age. Neurodevelopmental impairment, the primary outcome variable, was defined as the presence of any 1 of the following: moderate or severe cerebral palsy, severe bilateral hearing loss, bilateral blindness, Bayley Mental Developmental Index or Psychomotor Developmental Index of <70. Death was included with neurodevelopmental impairment as a composite outcome. Results were compared for both twins, twin A, twin B, same-gender twins, unlike-gender twins, and singleton infants. Logistic regression analysis was performed to control for demographic and clinical factors that were different among the groups.

RESULTS

The cohort of infants who either died or were assessed for neurodevelopmental impairment consisted of 7630 singleton infants and 1376 twins. Logistic regression adjusting for clinical and sociodemographic risk factors showed an increased risk of death or neurodevelopmental impairment for twins as a group when compared with the singletons. On analyzing twin A and B separately as well, risk of death or neurodevelopmental impairment was increased in both twin A and twin B.

CONCLUSIONS

Twin gestation in extremely low birth weight infants is associated with an independent increased risk of death or neurodevelopmental impairment at 18 to 22 months' corrected age compared with singleton-gestation infants. Both first- and second-born twins are at increased risk.

[The maternal and fetal outcome of 122 triplet pregnancies]

INTRODUCTION

The wide use of infertility drugs and assisted reproduction has resulted in 4- to 5-fold increase in the incidence of triplet pregnancies, which carry an extremely high risk of maternal complications and adverse perinatal outcome. In Hungary, reduction of multifetal pregnancies is available for all pregnant women with multifetal gestation since 1998. The goal of the procedure is to ensure better outcome for surviving fetuses. Counseling of pregnant patients should include the maternal and fetal risks of triplet gestation without multifetal pregnancy reduction.

AIM

To assess the risk of maternal complications, stillbirth, perinatal and neonatal mortality rates, and risk of neonatal morbidity in non-reduced triplets in a large case series, representing the Hungarian triplet population.

METHODS

The study population consisted of triplets delivered between July 1st, 1990 and June 30th, 2006, at the 1st Department of Obstetrics and Gynecology. All three fetuses had to be alive on the 18th-week ultrasound scan to be eligible.

RESULTS

Out of the 122 cases, 8 (6.6%) ended in midtrimester miscarriage, 114 (93.4%) ended in delivery. There were no maternal deaths. The most common antepartum maternal complications were pregnancy-induced hypertension (16.7%), gestational diabetes mellitus (18.4%), thrombocytopenia (20.2%), anemia (16.7%) and intrahepatic cholestasis (9.7%). Preterm labor requiring tocolysis occurred in 57.9%, preterm premature rupture of membranes in 32.5%. Prophylactic cerclage was performed in 15.8% of cases, and 69.3% of patients received steroid prophylaxis. The mean gestational age at delivery was 32.3 +/- 3.2 weeks. The rates of very early (<28 weeks) and early (<32 weeks) preterm deliveries were 8.8% and 42.1%, respectively. The mean 5-minute Apgar score was 9.2 +/- 0.8, and the mean birth weight at delivery was 1664 +/- 506 g. 38.0% of infants were very low birth weight (<1500 g). Stillbirth, crude perinatal mortality and corrected perinatal mortality rates were 23.4 per thousand, 64.3 per thousand and 27.4 per thousand, respectively. 11.7 per thousand of infants had some major congenital anomaly. 54.4% of infants required ventilation or oxygen therapy or both. The most common neonatal complication were respiratory distress (17.1%), transitory tachypnea (5.2%), sepsis or pneumonia (25.5%), intraventricular hemorrhage (4.3%) and jaundice (11.4%).

CONCLUSIONS

Both the maternal and neonatal risks should be considered when patients with triplets are counseled before the decision to continue the triplet gestation or to choose multifetal pregnancy reduction is made.

Does assisted reproduction technology, per se, increase the risk of preterm birth?

There is little doubt that all methods of assisted reproduction increase the likelihood of multiple pregnancy and, as a result, increase the likelihood of preterm birth. Data from the East Flanders Prospective Twin Study clearly show that the proportion of spontaneous to iatrogenic twins has changed from 25:1 to 1:1 over the past two decades. Data from the very low birthweight (VLBW) Infant Database of the Israel Neonatal Network showed that 10% of VLBW singletons were a result of assisted reproduction compared with 60% of the VLBW twins and 90% of the VLBW triplets. Irrespective of plurality, an association between preterm birth and assisted reproduction has long been suspected and was related to causes such as iatrogenic preterm birth (in the so-called 'premium' pregnancies), fertility history, past obstetric performance and to underlying medical conditions of the female partner. With more data available, a clearer picture is defined. Two different, recent meta-analyses showed that singleton pregnancies resulting from in vitro fertilisation (IVF) have increased rates of preterm birth at <33 weeks of gestation (OR 2.99; 95% CI 1.54-5.80), at <37 weeks of gestation (OR 1.93; 95% CI 1.36-2.74) and a relative risk of 1.98 (95% CI 1.77-2.22) for preterm birth in singleton pregnancies resulting from in vitro fertilisation embryo transfer/gamete intra fallopian transfer (IVF-ET/GIFT) compared with naturally conceived pregnancies. Since there is no way to predict which pregnant woman is at increased risk of preterm birth, it may be advisable to consider all pregnancies after assisted reproduction as being at risk. In any case, the most appropriate endpoint after assisted reproduction should also include preterm or term birth as measure of success.

Slow change in body mass index during early triplet pregnancy is associated with decreased birth weight

OBJECTIVE

This study evaluates the impact of an average change in body mass index (BMI) during the first 16-25 weeks on outcomes of triplet pregnancies.

STUDY DESIGN

In this retrospective observational study we evaluated a cohort of triplets born to 1235 nulliparas and 705 multiparas. The difference between the pregravid body mass index (BMI) and that obtained upon admission at 16-25 weeks' gestation was averaged to obtain the weekly change in BMI, defined as slow, typical, or fast by values<1SD, +/-1SD, and >1SD from the mean average weekly change in BMI. We compared gestational age and birth weight parameters in these three subgroups and by parity.

RESULTS

The average weekly BMI-adjusted weight gain was 0.18+/-0.08 and 0.17+/-0.08 kg/m2/week for nulliparas and multiparas, respectively. In both parity groups, differences were noted between slow and typical and between slow and fast, but not between typical and fast weight gain. Nulliparas with slow weight gain had a significantly higher incidence of infants weighing<1000 g (OR 2.0-2.5), 1000-1500 g (OR 1.4 compared with fast weight gain), and included 60-100% more sets with at least 1 SGA infant. In multiparas, there was no effect on gestational age, but otherwise, a similar trend for birth weight parameters was found.

CONCLUSION

Slow weekly change in BMI (<1 SD from the mean) at 16-25 weeks is associated with decreased birth weight but there was no advantage for fast over a typical weigh gain.

Non-selective fetal reduction is malpractice

Non-selective multifetal pregnancy reduction is carried out to reduce healthy higher order multiple fetuses to one or two fetuses. No studies exist to show any benefit of this practice and a Cochrane review, as well as investigators in the field, have not found any justification for such practice. From a medical point of view, this non evidence-based practice is not following good clinical practice. Any practice that transfers more than one or two embryos, for instance due to commercial interests, should be abandoned by the international medical community because multifetal pregnancies can, to a large extent, be avoided by transferring only one or a maximum of two fertilized eggs by in vitro fertilization. Further, ovarian stimulating programs should strictly adhere to protocols aiming at mono-ovulation.

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

BACKGROUND

Triplet pregnancies are associated with a high risk of miscarriage and early preterm birth. It is uncertain if the outcome is improved by embryo reduction (ER).

METHODS

We examined trichorionic triplet pregnancies with three live fetuses at 10-14 weeks of gestation that were managed expectantly or by ER. The two groups were compared for the rates of miscarriage, defined as pregnancy loss before 24 weeks, and preterm delivery prior to 32 weeks. In addition, systematic searches were performed to identify studies comparing outcomes in expectant management versus ER in triplet pregnancies.

RESULTS

We combined data from 365 pregnancies managed in our centre with those of five previous studies. In total there were 893 pregnancies. In the ER group (n=482) compared to the expectantly managed group (n=411), the rate of miscarriage was higher [8.1 versus 4.4%; relative risk (RR)=1.83, 95% confidence interval (CI)=1.08-3.16, P=0.036] and the rate of early preterm delivery was lower (10.4 versus 26.7%, RR=0.37, 95% CI=0.27-0.51, P<0.0001). It was calculated that seven (95% CI=5-9) reductions needed to be performed to prevent one early preterm delivery, while the number of reductions that would cause one miscarriage was 26 (95% CI=14-193).

CONCLUSIONS

In trichorionic triplets, ER to twins is associated with an increase in the risk of subsequent miscarriage and decrease in risk of early preterm birth.

Fetal reduction

Fetal Reduction has been employed over the past two decades as a mechanism to reduce the morbidity and mortality of multiple pregnancies. Utilization of the procedure has increased dramatically as IVF has become commonplace but the average starting number has decreased with the transfer of fewer embryos. Success rates from fetal reduction have improved as a function of increasing experience, better ultrasound, and lower starting numbers. Genetic diagnosis prior to reduction can improve the overall outcomes. Reduction of triplets or more clearly improves outcomes, and reduction of twins to a singleton is now a reasonable consideration.

The decreased rates of triplet births: temporal trends and biologic speculations

Recent data from the US and from England and Wales demonstrate decreasing rates of higher-order multiple births and represent, for the first time, a striking change in trend when compared with the previous steep 4-fold increase since the early 1980s. However, the incidence of other multiples--twins--continued to escalate. The most probable reasons for this change are new embryo transfer guidelines and availability of multi-fetal pregnancy reduction procedures. Because actual numbers of higher-order multiples are by far lower than the number of twins, and because twins are predictably associated with significant perinatal morbidity and mortality, the implications of the ever-increasing multiple birth rates are no less alarming. As long as the incidence of twins is not reduced, the decreasing incidence of higher-order multiples, per se, does not herald the end of the epidemic of multiple births.