Triple trouble: uncovering the risks and benefits of early fetal reduction in trichorionic triplets in a large national Danish cohort study

BACKGROUND

Triplet pregnancies are high risk for both the mother and the infants. The risks for infants include premature birth, low birthweight, and neonatal complications. Therefore, the management of triplet pregnancies involves close monitoring and may include interventions, such as fetal reduction, to prolong the pregnancy and improve outcomes. However, the evidence of benefits and risks associated with fetal reduction is inconsistent.

OBJECTIVE

This study aimed to compare the outcomes of trichorionic triplet pregnancies with and without fetal reduction and with nonreduced dichorionic twin pregnancies and primary singleton pregnancies.

STUDY DESIGN

All trichorionic triplet pregnancies in Denmark, including those with fetal reduction, were identified between 2008 and 2018. In Denmark, all couples expecting triplets are informed about and offered fetal reduction. Pregnancies with viable fetuses at the first-trimester ultrasound scan and pregnancies not terminated were included. Adverse pregnancy outcome was defined as a composite of miscarriage before 24 weeks of gestation, stillbirth at 24 weeks of gestation, or intrauterine fetal death of 1 or 2 fetuses.

RESULTS

The study cohort was composed of 317 trichorionic triplet pregnancies, of which 70.0% of pregnancies underwent fetal reduction to a twin pregnancy, 2.2% of pregnancies were reduced to singleton pregnancies, and 27.8% of pregnancies were not reduced. Nonreduced triplet pregnancies had high risks of adverse pregnancy outcomes (28.4%), which was significantly lower in triplets reduced to twins (9.0%; difference, 19.4%, 95% confidence interval, 8.5%-30.3%). Severe preterm deliveries were significantly higher in nonreduced triplet pregnancies (27.9%) than triplet pregnancies reduced to twin pregnancies (13.1%; difference, 14.9%, 95% confidence interval, 7.9%-21.9%). However, triplet pregnancies reduced to twin pregnancies had an insignificantly higher risk of miscarriage (6.8%) than nonreduced twin pregnancies (1.1%; difference, 5.6%; 95% confidence interval, 0.9%-10.4%).

CONCLUSION

Triplet pregnancies reduced to twin pregnancies had significantly lower risks of adverse pregnancy outcomes, severe preterm deliveries, and low birthweight than nonreduced triplet pregnancies. However, triplet pregnancies reduced to twin pregnancies were potentially associated with a 5.6% increased risk of miscarriage.

The Timing of the Maternal Recognition of Pregnancy Is Specific to Individual Mares

The present experiment aimed at determining whether the timing of the maternal recognition of pregnancy (MRP) was specific to individual mares by determining when luteostasis, a failure to return to oestrus, reliably occurred in individuals following embryo reduction. Singleton (n = 150) and synchronous twin pregnancies (n = 9) were reduced in 10 individuals (5-29 reductions/mare) at pre-determined time points within days 10 (n = 20), 11 (n = 65), 12 (n = 47), 13 (n = 12) or 14 (n = 15) of pregnancy. Prior to embryo reduction, the vesicle diameter was measured in 71% (106/150) of the singleton pregnancies. The interovulatory interval (IOI) was recorded on 78 occasions in seven of the mares in either non-pregnant cycles (n = 37) or those in which luteolysis followed embryo reduction (n = 41). The earliest time post-ovulation at which the embryo reduction resulted in luteostasis in an individual was 252 h (mid-Day 10). Consistency in luteostasis following embryo reduction showed individual variation between mares (272-344 h). Binary logistic regression analysis showed an individual mare effect (p < 0.001) and an effect of the interval post-ovulation at which embryo reduction was undertaken (p < 0.001). However, there was no significant effect of vesicle diameter at the time of embryo reduction (p = 0.099), nor a singleton or twin pregnancy (p = 0.993), on the dependent of luteolysis or luteostasis. The median IOI between individual mares varied significantly (p < 0.05) but was not correlated to the timing of MRP. The timing of MRP varied between the mares but was repeatable in each individual. The factors and mechanisms underlying the individuality in the timing of MRP were not determined and warrant further study.

Procedural and obstetric outcomes after embryo reduction vs fetal reduction in multifetal pregnancy

OBJECTIVE

To compare the obstetric outcome and incidence of procedure-related adverse events after embryo reduction (ER) vs fetal reduction (FR), in multifetal pregnancies undergoing reduction to twins or singletons.

METHODS

We analyzed retrospectively data from multifetal pregnancies that underwent transvaginal ER (n = 181) at a mean gestational age of 7.6 weeks or transabdominal FR (n = 115) at a mean gestational age of 12.9 weeks between December 2006 and January 2017. FR was performed after a detailed fetal anomaly scan. The two groups were compared with respect to obstetric outcomes, such as incidence of miscarriage, early or late preterm delivery, maternal complications and fetal loss, and procedure-related adverse events, including incidence of subchorionic hematoma and procedure-related fetal loss.

RESULTS

Compared with pregnancies that underwent ER, the incidence of procedure-related fetal loss was lower in the FR group (7.2% vs 0.9%; P = 0.039; odds ratio (OR), 0.12; 95% CI, 0.02-0.89). Mean gestational age at delivery for twins was 34.2 weeks in the ER group and 35.7 weeks in the FR group (P = 0.014). Compared with the ER group, the FR group had lower miscarriage (8.8% vs 2.6%; P = 0.045; OR, 0.28; 95% CI, 0.08-0.97) and overall fetal loss (13.3% vs 5.2%; P = 0.031; OR, 0.36; 95% CI, 0.14-0.91) rates.

CONCLUSIONS

The FR procedure is, overall, a better and safer approach to reducing morbidity and mortality in multifetal pregnancies. Spontaneous demise of one fetus may occur after ER, and FR has the advantage that chorionic villus sampling and ultrasound screening for increased nuchal translucency and anatomical defects can be conducted before the procedure. The ER approach is still reasonable when a patient's religious or other ethical concerns are of primary importance. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

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.

Intrafetal laser ablation for embryo reduction from dichorionic triplets to dichorionic twins

OBJECTIVE

To report the outcome of dichorionic (DC) triplet pregnancies reduced to DC twins by laser ablation of the pelvic vessels of one of the monochorionic (MC) twins.

METHODS

Intrafetal laser embryo reduction (ER) from DC triplets to DC twins was carried out in 61 pregnancies at 11 + 0 to 14 + 3 weeks' gestation. Pregnancy outcome was examined.

RESULTS

Intrafetal laser was successfully carried out in all cases, but ultrasound examination within 2 weeks of the procedure demonstrated that the MC cotwin had died in 28 (45.9%) cases and was alive in the other 33 (54.1%). In the DC group, there was one miscarriage at 23 weeks, one neonatal death after delivery at 26 weeks and in the other 31 cases there were two live births at a median gestational age of 35.3 (range, 30.4-38.4) weeks. In the 28 cases in which both MC fetuses died, there was one miscarriage at 16 weeks and in the other 27 cases the separate triplet was liveborn at a median gestation of 38.2 (range, 32.2-42.1) weeks. The overall rate of miscarriage was 3.3% (2/61) and that of preterm birth (PTB) at < 33 weeks was 6.8% (4/59).

CONCLUSIONS

In the management of DC triplet pregnancies, ER to DC twins by intrafetal laser ablation is associated with lower rates of miscarriage or early PTB, compared with expectant management or ER by fetal intracardiac injection of potassium chloride. However, about half of the pregnancies result in the birth of one rather than two babies. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Embryo reduction: our experience

BACKGROUND

The transvaginal ultrasound-guided embryo reduction technique is a feasible option for the prevention and management of the medical and obstetric risks associated with high-order multiple pregnancy resulting from assisted reproductive treatment.

METHOD

Multifoetal pregnancy reduction was carried out in 51 in vitro fertilisation pregnancies (IVF) and one intrauterine quintuplet pregnancy resulting from intrauterine insemination (IUI) using transvaginal approach under ultrasonographic guidance.

RESULTS

Of the 52 embryo reduction procedures, 48 (92%) were performed between the seventh and eighth weeks of gestation, three between eighth and ninth weeks and one in the 10th week of gestation. Forty-nine patients (94%) underwent reduction from triplets to twins, two from quadruplet to twins, and one from quintuplet to twin pregnancy. The average time required for the embryo reduction was 5.0 ± 0.5 minutes per sac in early gestation (6th-9th weeks), increasing to 8.5 minutes per sac for later procedures, due to technical difficulties brought about by increased embryo size and mobility. All embryo reduction procedures were successfully performed in a single session.

CONCLUSION

Transvaginal ultrasound guided embryo reduction technique performed between seventh and eighth-weeks of gestation is an effective and safe procedure for embryo reduction.