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 the infants include premature birth, low birth weight, and neonatal complications. As a result, 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: Our study aims to compare the outcomes of trichorionic triplet pregnancies with and without fetal reduction, as well as with non-reduced dichorionic twin pregnancies and primary singletons.

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, stillbirth from 24 weeks, or intrauterine fetal death of one or two fetuses.

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

CONCLUSIONS: Triplet pregnancies reduced to twins had significantly lower risks of adverse pregnancy outcomes, severe preterm deliveries, and low birth weight than non-reduced triplets. However, potentially associated with a 5.6% increased risk of miscarriage.