Peripartum factors predicting the need for increased doses of postpartum rhesus immune globulin

To evaluate the need for increased doses of postpartum rhesus immune globulin in a woman at risk for rhesus alloimmunization.

Using data from the Nova Scotia Atlee Perinatal Database (NSAPD) and the Rh Program of Nova Scotia Database, Rh negative women delivering infants with a birth weight greater than 500 grams and gestational age greater than 20 weeks at the IWK Health Centre from 1998 to 2007 were identified. Within this population, Rh(D) negative women who received both antepartum and postpartum anti-D prophylaxis were identified. Logistic regression was used to estimate peripartum predictive factors for elevated postpartum Kleihauer and the need for administration of additional rhesus immune globulin.

The NSAPD and Rh Program Database identified 4323 Rh negative women who received both antepartum and postpartum prophylaxis from 1998 and 2007. Following logistic regression, a postpartum Kleihauer value of > 0.2% was found to be predicted by multiparity (OR 1.47; 95% CI 1.03 to 2.08), multiple gestation (OR 3.03; 95% CI 1.61 to 5.70), antepartum risks for fetomaternal hemorrhage (OR 63.6; 95% CI 30.2 to 134), and Caesarean section (OR 2.03; 95% CI 1.42 to 2.91). A postpartum Kleihauer value of > 0.5% was found to be predicted by antepartum risks for fetomaternal hemorrhage (OR 29.1; 95% CI 12.9 to 65.5), and Caesarean section (OR 2.01; 95% CI 1.18 to 3.42).

While there are recognized events that increase the risk for Rh(D) alloimmunization, multiparity, multiple gestation, and Caesarean section should be additional factors for consideration, especially with rising rates of CS. Adequate postpartum prophylaxis may be optimized by conducting routine screening for fetomaternal hemorrhage, especially when lower doses of Rh(D) immune globulin are administered.