Among 106 patients in a single center in their first alloimmunized pregnancy with anti-D, 57% did not develop a critical titer. Of those who did develop a critical titer, 54% developed HDFN of any severity, 26% developed severe disease (hydrops, fetal demise, need for IUT), 4% developed moderate disease (need for neonatal exchange transfusion), and 24% developed mild disease (need for phototherapy or simple blood transfusion)37.
Another recent 15-year retrospective study in a single center observed an IUT rate of 77% among at risk pregnancies with critical titers and MCA-PSV MoM values above 1.5. The average gestational age at birth for this group was 34 weeks. Among those with critical titers but PCA-PSV values below 1.5 MoM, no IUT was required and the average gestational age at birth was 37 weeks 2.
With appropriate monitoring and skilled intervention, fetal survival rate has increased in recent years. The table below provides survival outcomes in a range of populations and treatment circumstances at some of the most experienced fetal centers in the world.
Fetal/Infant Survival Rate:
75%
Treatment Summary
Routine ultrasound and amniocentesis prior to 2007, then MCA-PSV. IUT in 5 cases.
Population
84 pregnancies with C/c, D, and/or e antibodies with critical titers at first assessment (>16).
Country, Time Period
Saudi Arabia, 2004-2009
Author, Year
Bondagji, 2012 42
Fetal/Infant Survival Rate:
88%
Treatment Summary
Half of pregnancies being monitored by fetal hematocrit, others by MCA-PSV (no significant difference between groups) and receiving IUTs.
Population
71 pregnancies with reported IUTs due to maternal alloimmunization
Country, Time Period
Australia, New Zealand, Canada, UK, Ireland, Belgium, Argentina, 2009-2013
Author, Year
Dodd, 2018 41
Fetal/Infant Survival Rate:
Overall
(N=99): 76%
1995-2000 Amino Group
(N=74): 73%
2001-2004 MCA group
(N-25): 84%
Treatment Summary
1995-2000: Amniocentesis between 26-28 weeks with subsequent amniocenteses based on results of first exam and ultrasonographic signs of fetal compromise. IUT if moderate to severe anemia prior to 34 weeks.
2001-2004: Weekly MCA PSV. IUT if moderate to severe anemia prior to 34 weeks.
Population
99 pregnancies with D antibodies and critical titers (>16).
Country, Time Period
Brazil, 1995-2004
Author, Year
Nardozza, 2007 43
Fetal/Infant Survival Rate:
97%
Treatment Summary
Fetuses with severe anemia requiring and receiving intrauterine transfusion.
Population
334 fetuses undergoing 937 intrauterine transfusions in 2001-2015
Country, Time Period
Netherlands, 1988-2015
Author, Year
Zwiers, 2017 16
Fetal/Infant Survival Rate:
84%
Treatment Summary
Fetuses being monitored through weekly MCA scans and IUTs performed through 34 weeks (or delivery if later).
Population
57 pregnancies with at risk-fetuses and critical titers (>16) or Kell pregnancies of any titer requiring IUTs.
Country, Time Period
Spain, 2002-2017
Author, Year
Sanchez-Duran, 2019 2
Fetal/Infant Survival Rate:
100%
Treatment Summary
Fetuses receiving IUTs.
Population
56 pregnancies with reported IUTs due to maternal alloimmunization
Country, Time Period
Belgium, 2000-2014
Author, Year
Pasman, 2015 40
Fetal/Infant Survival Rate:
100%
Treatment Summary
Fetuses being monitored through titers every four weeks or every two weeks if rapidly increasing
Population
38 pregnancies with at-risk fetuses and non-critical titers (<16).
Country, Time Period
Australia, New Zealand, Canada, UK, Ireland, Belgium, Argentina, 2009-2013
Author, Year
Sanchez-Duran, 2019
Estimates above reflect the positive impact of close monitoring of titers, frequent MCA-PSV Doppler ultrasound, and prompt initiation of IUTs. Studies reporting lower survival rates also show practice standards not consistent with current recommendations. Note as well the significance of RhIG prophylaxis and the importance of administering during early pregnancy bleeding, at the beginning of the third trimester and within 72 hours of birth to a RhD positive fetus. Bondaghi 42 reported that in Saudi Arabia between 2004 and 2009, failure to administer RhIG was common and 24% of women who were RhD negative became sensitized, a glimpse of the effect of sub-optimal monitoring and management of the RhD negative pregnant woman.
