# Evaluating the safety and outcomes of third-trimester selective termination in dichorionic twin pregnancies with discordant anomalies—a standardized approach for counseling

## TL;DR

This study examines the risks and outcomes of terminating one twin in the third trimester of a twin pregnancy, finding a high risk of early birth but good survival for the remaining twin.

## Contribution

The study introduces a standardized approach for counseling patients about third-trimester selective termination in twin pregnancies.

## Key findings

- Third-trimester selective termination is linked to a high risk of preterm birth within four weeks.
- Clinical chorioamnionitis was more common in cases delivering within four weeks of termination.
- Polyhydramnios and reduction of the presenting fetus are significant risk factors for early delivery.

## Abstract

To evaluate procedure-related preterm birth (PTB) following third-trimester selective termination (ST) in DC twins and to compare delivery timing with expectantly managed discordant DC twins and non-anomalous DC twins.

A retrospective cohort study was conducted of all DC twin pregnancies undergoing third-trimester ST (> 28 weeks) at a tertiary care center (2003–2023). Pregnancies were classified as having procedure-related complications (delivery ≤ 4 weeks) or uneventful (delivery > 4 weeks). Comparator cohorts included expectantly managed discordant DC twins and non-anomalous DC twins. Outcomes included timing of delivery, cumulative incidence of PTB, and risk factor analysis.

90 women with DC twin pregnancies elected for ST and 85 procedures were completed. Outcome was available for 81 cases; 48 (59.3%) delivered ≤ 4 weeks after ST and 33 (40.7%) delivered later. Clinical chorioamnionitis was more common within the group delivered ≤ 4 weeks (35.4% vs. 0%; p = 0.001). Cumulative PTB incidence showed accelerated delivery between 32 and 34 weeks after ST. Independent risk factors for delivery ≤ 4 weeks included polyhydramnios (OR 5.68) and reduction of the presenting fetus (OR 6.51). Comparator cohorts exhibited substantially lower PTB incidence.

Third-trimester ST in DC twins is associated with high PTB risk, but excellent co-twin survival. The first 4 weeks after ST represent a critical vulnerability period, and risk is strongly influenced by identifiable preprocedural factors. These findings support individualized counseling, later scheduling in high-risk pregnancies, should be considered.

The online version contains supplementary material available at 10.1007/s00404-026-08305-6.