Women who are Rhesus (Rh)-negative and exposed to fetal Rh-positive red cells are at risk for developing Rh alloimmunization putting a future Rh-negative fetus at risk of hemolytic disease of the fetus and newborn (HDFN).

Before the availability of anti-D immunoglobulin (anti-D Ig or Rho(D) immune globulin), HDFN was a major cause of morbidity and mortality.¹

• If anti-D Ig is given appropriately at 28-30 weeks GA and following delivery of an Rh-positive infant, the risk of alloimmunization is reduced to 0.1% from 16%.
• In Canada, the product’s tradename is “WinRho” but is also known as RhoGAM.
• Can be given IM or IV route.
• Anti-D Ig has been used in Canada since 1968 with very few serious effects reported – no infections but allergic reactions may occur.
• Not known to be harmful to a baby during pregnancy/breastfeeding.
• All Rh-negative pregnant women should be offered routine prophylaxis with anti-D immunoglobulin (anti-D Ig), during their third trimester of pregnancy.¹
• Evidence for benefit of prophylaxis following potentially sensitizing events in early pregnancy is less (particularly early in the first trimester with less fetomaternal blood exposure) but risks of administration are low therefore it is currently recommended.

Formerly dosed as micrograms (mcg) it is now “officially” International Units (IU).

• • 1500 IU = 300 mcg WinRho .
  • 250 IU = 50 mcg WinRho .

Anti-D immunoglobulin prophylaxis for RhD-negative women

RhD-negative women whose partner is, or might be D-positive, are candidates for anti-D Ig therapy as follows:

1. A single dose of 300 mcg or 1500 IU anti-D Ig at 28 weeks GA.
2. Another dose of 1500 IU within 72 hours of delivery of a D-positive newborn. If not given at delivery, anti-D Ig should be given as soon as possible up to 28 days after delivery. ²
3. After any event that is associated with fetomaternal bleeding:

• • Spontaneous, induced or threatened abortion.
  • Blunt abdominal trauma.
  • Ectopic pregnancy.
  • Fetal death in the second or third trimester.
  • Antepartum bleeding in the second or third trimester.
  • Diagnosis of a hydatiform mole.

WinRho Dosing prophylaxis based on gestational age and exposure event:  

• 250 IU (50 mcg) dose is recommended before 12 weeks gestation, although 1500 IU (300 mcg) can be administered if lower doses are not available.3.
• After 12 weeks, a 1500 IU (300-mcg) dose should be given.12.

Potentially sensitizing events

Fig 1. Comprehensive list of sensitizing events in pregnancy, adapted from Qureshi et al., 2014.

1. Anti-D Immunoglobulin (RhoGam) in Early Pregnancy
   Podcast EP 86
   – CORE EM

    

   
   

2. RETURN OB VISITS
   Podcast Feb 2018
   – PIMPED podcast

   
   

3. Erythrocyte Alloimmunization and Pregnancy
   Anna R Baur, MD et al. Jul 02, 2018.
   – Medscape clinical guidelines

   
   

4. Rh Sensitization During Pregnancy, Information for patients.
   – Health link BC

   
   

1. BCSH guideline for the use of anti-D immunoglobulin for the prevention of haemolytic disease of the fetus and newborn: Guidelines. Transfus Med.
   Qureshi H, Massey E, Kirwan D, et al.  2014;24(1):8-20.
   doi:10.1111/tme.12091

   
   

2. No. 133-Prevention of Rh Alloimmunization
   Fung KFK, Eason E. .2018;40(1):e1-e10.
   – J Obstet Gynaecol Can.

    

   
   

3. No. 181: Prevention of Rh D Alloimmunization.
   American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics in collaboration with Robert M. Silver, MD. 2017;130(2):e57-e70. doi:10.1097/AOG.0000000000002232
   – Practice Bulletin  Obstet Gynecol.