The Advisory Committee on Immunization Practices (ACIP) recommends immune globulin for post-exposure prophylaxis (PEP) in selected individuals at increased risk for severe measles, including pregnant patients without evidence of measles immunity, infants younger than 12 months, and severely immunocompromised patients. ACIP recommends a dose of 0.5 mL/kg for intramuscular immune globulin (IGIM) and 400 mg/kg for intravenous immune globulin (IVIG) for PEP. For pregnant patients specifically, ACIP states that intravenous immune globulin (IVIG) should be administered because pregnant patients may be at higher risk for severe measles and its complications. The pregnancy-specific recommendation further states that IVIG should be administered at doses sufficient to achieve protective measles antibody titers but does not explicitly reiterate the 400 mg/kg dose within pregnancy recommendations. However, Centers for Disease Control and Prevention (CDC) guidance explicitly recommends IVIG 400 mg/kg for susceptible pregnant patients requiring measles PEP. Of note, neither the ACIP recommendations nor current CDC guidance specify whether the dose should be calculated using total (actual) body weight, ideal body weight, or adjusted body weight. [1], [2]
A 2019 review evaluating the use of polyvalent immunoglobulin for measles PEP reported that multiple national guidelines recommend passive immunization for non-immune pregnant women because of their increased risk for severe disease and complications. In the United States, IVIG 400 mg/kg is recommended, consistent with ACIP recommendations. Canadian guidelines recommend either IGIM 0.5 mL/kg (maximum 15 mL) or IVIG 400 mg/kg, with IVIG suggested for patients weighing more than 30 kg or when the required IM injection volume is a concern. In the United Kingdom, IGIM 2,250 mg (15 mL) is recommended for non-immune pregnant women. Similarly, the authors do not specify which body weight should be used for dose calculation. [3]
According to the Ontario Regional Blood Coordinating Network, IVIG for measles post-exposure prophylaxis should be administered as a single 0.4 g/kg dose using actual body weight during pregnancy. Although adjusted body weight is otherwise specified for IVIG dosing, the guidance explicitly directs the use of actual body weight in pregnant patients; ideal body weight is not specified. [4]
A National Health Service (NHS; UK) measles post-exposure prophylaxis flowchart recommends a single 5 g intravenous dose of Privigen for pregnant patients. For immunosuppressed pregnant patients, the recommended dose is 0.15 g/kg using booking weight. [5]
Although not specific to measles post-exposure prophylaxis, a 2026 Australian National Immunoglobulin Governance Advisory Committee position statement recommends adjusted body weight dosing for immunoglobulin in selected adult patients, based on evidence that immunoglobulin distributes predominantly within the intravascular and extracellular fluid compartments with minimal distribution into adipose tissue. The statement specifically excludes pregnant patients from use of the adjusted body weight dosing calculator and does not recommend applying the calculator in this population. No alternative dosing weight is specified for pregnant patients, and the document states that clinical judgment should be applied. [6]
Additionally, the 2024 ACOG Practice Advisory recommends administering IVIG 400 mg/kg within 6 days of measles exposure for pregnant patients without evidence of immunity. However, the guideline does not specify whether the dose should be calculated using total body weight, ideal body weight, or adjusted body weight, nor does it provide any pregnancy-specific recommendations regarding weight selection for IVIG dosing. [7]