Prospective interventional study
Between 2016 to 2018, RhD negative women with a fetus typed RHDpositive, were asked to participate in the study, at their appointment to receive RAADP, 1500 IU (Rhophylac®, CSL Behring GmbH, Marburg, Germany) in gestational week 28. Eligible participants were healthy women without previous history of pregnancy complications, with a singleton pregnancy and estimated due date confirmed by ultrasound examination in the second trimester. Exclusion criteria were administration of anti-D prophylaxis earlier in the current pregnancy, a multiple pregnancy, presence of maternal erythrocyte alloantibodies at time of inclusion or medication other than vitamins, folic acid and iron supplement. Before inclusion, a routine obstetric history was checked, as well as blood pressure. Information on body height and weight was received from the first antenatal visit in gestational week 10-14.
The women were given oral and written information from a research midwife and if they agreed they received a second dose of anti-D prophylaxis 1500 IU in gestational week 38. Anti-D concentration was analysed before the anti-D administration in gestational week 38 and then monitored weekly until the correspondent time of 43 weeks gestational age, including postdelivery. The quantitative anti-D analysis was done only daytime weekdays, so administration of anti-D prophylaxis after delivery was based on the type-and-screen test. If the erythrocyte antibody screen was positive at delivery, the women received no more prophylaxis, if the anti-D level was low at delivery, defined as negative or a weak reaction in the routine antibody screen, it was decided to recommend anti-D prophylaxis for safety purposes. 39 pregnant women gave informed consent and were included in the study. The demographic characteristics of the included women are shown in Table 1.