Selective fetal reduction of uncomplicated dichorionic twins on parental request vs ongoing twins and pregnancy outcomes: a systematic review and meta-analysis

OBJECTIVE

This study aimed to assess the effect of elective fetal reduction on maternal–fetal outcomes in uncomplicated twin pregnancies compared with ongoing twin pregnancies.

DATA SOURCES

The data sources included PubMed, Scopus (until December 2023), and references of retrieved articles.

STUDY ELIGIBILITY CRITERIA

We included clinical studies examining the association between selective fetal reduction of uncomplicated dichorionic twins on pregnancy outcomes.

METHODS

Quality assessment of observational studies was conducted using the ROBINS-I tool. The overall quality of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework. A quantitative analysis was performed for electively reduced dichorionic twins. The primary outcome was preterm birth. The secondary outcomes were gestational age at delivery, stillbirth, neonatal intensive care unit admission, gestational diabetes mellitus, preeclampsia, and pregnancy loss at <24 weeks of gestation. Summary odds ratios with 95% confidence intervals were calculated, and random-effects models were used for data synthesis.

RESULTS

The initial electronic search yielded 745 studies; 175 studies were further identified from reference citations. Five articles included appropriate data and were finally included in the meta-analysis. All studies were evaluated as having “moderate risk of bias.” These 5 studies reported on dichorionic twins. Elective reduction in dichorionic twins reduces the risk for preterm birth at <37 weeks (4 studies; n=1577; odds ratio, 0.14; 95% confidence interval, 0.09–0.22; moderate-quality evidence), <34 weeks (3 studies; n=1335; odds ratio, 0.22; 95% confidence interval, 0.07–0.69; low-quality evidence), and <32 weeks (3 studies; n=1335; odds ratio, 0.31; 95% confidence interval, 0.11–0.88; low-quality evidence), gestational diabetes (3 studies; n=1410; odds ratio, 0.57; 95% confidence interval, 0.33–0.97; low-quality evidence), pregnancy-associated hypertensive disorders (2 studies; n=581; odds ratio, 0.29; 95% confidence interval, 0.10–0.83; low-quality evidence), and birthweight <10th centile (2 studies; n=1163; odds ratio, 0.27; 95% confidence interval, 0.17–0.43; moderate-quality evidence) and <5th centile (2 studies; n=1163; odds ratio, 0.31; 95% confidence interval, 0.19–0.50; low-quality evidence), and increases gestational age at delivery (4 studies; n=1362; mean difference, 2.93 weeks; 95% confidence interval, 2.08–3.77; moderate-quality evidence). The risks for stillbirth (2 studies; n=1311; odds ratio, 1.63; 95% confidence interval, 0.43–6.21; very low-quality evidence) and pregnancy loss at <24 weeks (3 studies; n=1436; odds ratio, 1.20; 95% confidence interval, 0.55–2.58; very low-quality evidence) were not statistically significantly different.

CONCLUSION

Compared with ongoing dichorionic twin pregnancies, dichorionic pregnancies that undergo elective selective fetal reduction are associated with lower incidences of preterm birth at <37, <34, and <32 weeks, birthweight <10th and <5th centile, gestational diabetes, and hypertensive disorders of pregnancy, and later gestational age at delivery by almost 3 weeks. These associations were often based on very low-quality evidence. Thus, these results should be interpreted with caution, and further studies should be conducted.