Maternal "mirror" Syndrome: Evaluating the Benefits of Fetal Therapy.

ObjectiveTo evaluate maternal and perinatal outcomes following fetal intervention in the context of maternal "mirror" syndrome.Study DesignA multicenter retrospective study of all cases of fetal hydrops complicated by maternal "mirror" syndrome and treated by any form of fetal therapy between 1995 and 2022. Medical records and ultrasound images of all cases were reviewed. "Mirror" syndrome was defined as fetal hydrops and/or placentomegaly associated with the maternal development of pronounced edema, with or without pre-eclampsia. Fetal hydrops was defined as the presence of abnormal fluid collections in >= 2 body cavities.ResultsTwenty-one pregnancies met the inclusion criteria. Causes of fetal hydrops and/or placentomegaly included fetal lung lesions (n = 9), twin-twin transfusion syndrome (n = 6), severe fetal anemia (n = 4), and others (n = 2). Mean gestational age at "mirror" presentation was 27.0 +/- 3.8 weeks. Maternal "mirror" syndrome was identified following fetal therapeutic intervention in 14 cases (66.6%). "Mirror" symptoms resolved or significantly improved before delivery in 8 (38.1%) cases with a mean interval from fetal intervention to maternal recovery of 13.1 days (range 4-35). Three women needed to be delivered because of worsening "mirror" syndrome. Of the 21 pregnancies treated (27 fetuses), there were 15 (55.5%) livebirths, 7 (25.9%) neonatal deaths and 5 (18.5%) intra-uterine deaths.ConclusionFollowing successful treatment and resolution of fetal hydrops, maternal "mirror" syndrome can improve or sometimes completely resolve before delivery. Furthermore, the recognition that "mirror" syndrome may arise only after fetal intervention necessitates hightened patient maternal surveillance in cases of fetal hydrops. What's already known about this topic?"Mirror" syndrome, where maternal symptoms reflect fetal hydrops, affects 20%-30% of fetal hydrops cases. Case studies show maternal condition improvement following successful fetal therapy. However, comprehensive research to understand fetal therapy's effect on maternal and fetal outcomes is lacking.What does this study add?This study provides new insights into the efficacy of fetal interventions for "mirror" syndrome and, in particular, underscores the importance of patient counseling, given the significant maternal morbidity involved.