Maternal anemia at admission for labor in twin pregnancies: an indicator of adverse maternal and neonatal outcome

Purpose: Maternal anemia during pregnancy is associated with adverse obstetrical outcomes. This study aimed to assess maternal and neonatal outcomes in women with anemia in twin pregnancies, compared to women with normal hemoglobin levels. Methods: A multicenter retrospective cohort study was conducted including women with twin pregnancies who delivered at 24–42 weeks between 2005 and 2021. Maternal and neonatal outcomes were compared between those who had diagnosis of maternal anemia upon admission for labor (hemoglobin < 11 g/dL), to those who have normal hemoglobin level. The primary outcome was composite adverse neonatal outcomes. Univariate analysis was followed by multivariate analysis to control potential confounders. Results: During the study period, there were 5,530 twin deliveries; 5,004 women met the inclusion criteria. The maternal anemia prevalence upon admission was 16.8% (n = 840). After controlling for potential confounders, we found an independent association between maternal anemia in twin pregnancies and composite adverse neonatal outcomes for both twins—aOR 1.81 (1.55–2.12) for twin A and aOR 1.77 (1.51–2.06) for twin B. Anemia was also independently associated with higher risk for preterm delivery, cesarean delivery, maternal blood product transfusion and NICU admission for both twins. Conclusions: Maternal anemia in twin pregnancies is associated with an increased risk of adverse maternal and neonatal outcomes. Clinicians should be aware of this condition, consider appropriate interventions for correcting the anemia, and ensure close monitoring of both the mother and the neonates. Further research is warranted to evaluate the effectiveness of anemia correction strategies in reducing obstetric burden.