Introduction: Anti‐D alloimmunization is the most common cause of severe hemolytic disease of the fetus and newborn (HDFN). The management of pregnancies affected by less frequent red blood cell (RBC) antibodies poses a challenge to clinicians, and perinatal outcomes are less well described. This study aimed to describe the frequency of clinically significant RBC antibodies in our pregnant population and analyze the risk of prenatal and postnatal treatment for HDFN in relation to our national risk classification system and management guidelines.Material and methods: A retrospective cohort study in the population of all alloimmunized singleton pregnancies in the Stockholm region 1990–2016. Descriptive summaries of different RBC antibodies and pregnancy outcomes were presented, the risks of intrauterine blood transfusion (IUT) and neonatal treatment for HDFN were estimated by type of antibodies.Results: Of the 1724 alloimmunized pregnancies, 1079 (63%) were at risk of HDFN and constituted our study cohort. Anti‐D was detected in 492 (46%) pregnancies, followed by anti‐E in 161 (15%), and anti‐c in 128 (12%). Eighty‐seven (8%) pregnancies had IUT, with the highest risk in pregnancies affected by anti‐D combined with other antibodies. The maximum titer recorded before IUT was 64 or above, except for two pregnancies affected by anti‐c, for which the maximum titers were 8 and 16. For the 942 (95%) live‐born neonates from 992 alloimmunized pregnancies without IUT, the median gestational age at birth was 38⁺⁵ weeks compared with 35⁺⁵ weeks for those who had IUT. Neonatal treatment was most common in the anti‐D alone and anti‐D combined groups, with 136 (57%) and 21 (44%), respectively, treated with phototherapy and 35 (15%) and 9 (20%) receiving exchange transfusions, respectively. For pregnancies complicated by moderate‐ and low‐risk antibodies, phototherapy was less frequent (32 [36%] and 21 [19%]) and exchange transfusion was rare (5 [6%] and 3 [3%]).Conclusions: Anti‐D, especially in combination with other antibodies, presents the highest risk of severe HDFN. The classification of less frequent and less well‐known RBC antibodies into risk groups can help clinicians in assessing the risk of HDFN and counseling alloimmunized pregnant women regarding the risk of prenatal and postnatal treatments.

We read with interest the recently published article in the Journal of Clinical Medicine, by Drozdowska-Szymczak et al

Introduction: The Nordic Fetal Therapy Alliance centralizes treatment of twin-to-twin transfusion (TTTS) to ensure high-quality fetal therapy. This study reports the outcomes of treated TTTS cases and highlights the importance of international collaboration. Methods: We conducted a prospective observational study on all pregnancies undergoing TTTS surgery between May 2019 and April 2022 in the Nordic countries. The primary outcome was perinatal survival at 28 days. Secondary outcomes were gestational age (GA) at delivery, procedure-related complications, and mode of delivery. Results: A total of 200 cases underwent fetal surgery; 185 were treated with fetoscopic laser photocoagulation (FLP), and 15 with primary selective reduction by cord occlusion (CO). FLP resulted in at least one surviving neonate in 86% and in at least two survivors in 64%. Median GA at surgery was 20+1 weeks (range 15+1; 29+0), and median GA at delivery was 32+2 weeks (range 24+3; 41+0). In the CO group, 80% had at least one surviving neonate. Preterm premature rupture of membranes occurred in 13.6% within the FLP group and none in the CO group. Post-laser twin-anemia polycythemia sequence occurred in 5.4%. Conclusion: Collaboration across borders on TTTS treatment in the Nordic region is possible, and outcome results are comparable to other International Centers.