Avaliação da antecipação do nascimento nas gestações de mães aloimunizadas Rh (D) com baixo risco para anemia fetal e neonatal assistidas no Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira

The delivery anticipation in pregnancies with Rh(D) alloimmunization and low risk of fetal and neonatal anemia assisted at IFF/FIOCRUZ INTRODUCTION The optimal timing for delivery in pregnancies complicated by Rh(D) alloimmunization it’s a controversial topic, with little evidence in literature. The decision for anticipation of delivery in a gestational age before term deserves special attention when we deal with the subgroup with low risk of anemia. PURPOSE Analyze the potential reasons that lead to a preterm birth in pregnancies with low risk of fetal and neonatal anemia at IFF/FIOCRUZ, comparing pregnancies with term neonates with the ones with preterm neonates in means of highest multiple of the mean of median cerebral artery peak velocity and neonatal hematocrit after delivery. MATERIAL AND METHODS Retrospective observational study, getting information from medical record of mother and neonate of pregnancies followed at IFF/FIOCRUZ for Rh(D) alloimmunization and low risk for fetal and neonatal anemia, defined by characteristics of obstetric history and prenatal care, that delivered at the same institution between January 2004 and December 2014. RESULTS Medical records of one hundred seventy-seven pregnancies with Ph(D) alloimmunization and low risk for fetal and neonatal anemia were evaluated. Delivery was indicated exclusively by perinatal hemolytic disease in 77,4% of them (IC 95% 70,5-83,3%). Prevalence of prematurity by any reason was 35,6% (IC95% 28,6 -43,1%) and of prematurity exclusively indicated by perinatal hemolytic disease 24,9% (IC95% 18,7-31,9%). In the group with preterm delivery a higher proportion of cases with PV ACM > 1,30MoM was found, with statistical significance (p < 0,05). Comparing the hematocrit mean between groups a statistic significant difference was also found, with the preterm birth neonates mean hematocrit lower (p < 0,05). CONCLUSIONS These results suggest that even in the low risk of anemia group there is a proportion of cases that get benefit from the preterm delivery as it stops progression of intrautero perinatal hemolytic disease and provides early institution of neonatal treatment. A new threshold different of that used for indication of intrautero transfusion might identify fetuses in the low risk of anemia group that could get benefit of premature delivery.