ANTI-RH IMMUNOPROPHYLAXIS AT 28 WEEKS: WHAT EFFECTS ON THE FETUS?

INTRODUCTION Anti-RH immunoprophylaxis was introduced in 1970 with the purpose of reducing the maternal immunization risk in all Rh negative women from 1% to 0.2% at 28 weeks of pregnancy. Despite the fact that several studies have proven that such a procedure does not cause relevant side effects on the newborn, it is also documented that a small amount of immunoglobulin anti-D can cross the placenta, coat Rh-D positive fetal red blood cells, causing mild haemolysis and secondary positivization of the direct Coombs test at birth. The aim of this study was to evaluate any other minimal impact on RhD positive newborns who had received anti-Rh immunoprophylaxis at 28 weeks of pregnancy (at a dose of 1,500 IU, 300 µg). METHODS This comparative and retrospective study included a pool of 284 RhD positive babies born to RhD negative mothers who delivered at a tertiary hospital within a one-year period (from 1 January to 31 December 2015). The group was divided into two subgroups: 143 women who had received immunoprophylaxis at the gestational age of the 28 weeks, and 141 women who had not. For each subgroup the following neonatal variables were considered, taken from the umbilical cord by blood gas analysis at birth: hemoglobin, bilirubinemia, standard base excess and pH. The Apgar score at the first and fifth minutes, direct Coombs test, neonatal icterus, need for phototherapy and days of hospitalization were also reported. Statistical analysis: the Chi square test was used to analyze statistically significant relations between the distribution of categorical variables. Student’s t test was used to compare significant differences in mean continuous variables between the two groups. A p value < 0.05 was considered statistically significant. RESULTS Besides the statistically significant difference between the two groups in the positivization of the direct Coombs’ test at birth (p 0.0001), no other statistically significant differences for all the others parameters under examination were found. CONCLUSIONS Our findings indicate that placental passage of anti-D immunoglobulin at 28 weeks of gestation does not produce any hematological changes related to hemolysis in RhD positive newborns. As it has already been reported in literature, newborns who were exposed to anti-D immunoglobulines during intrauterine life had a more frequently positive direct Coombs test at birth. The tendency of a prolonged hospitalization in the group who received anti-D prophylaxys seems more related to the low Apgar score at the 1st minute than to the need for phototherapy. We may conclude that the prevention of Rh isoimmunization by the injection of anti-D immunoglobulin brings a benefit in the prevention of hemolytic disease of the fetus and does not have any other even minimal impact on the RhD positive newborns.