Plasma donation (plasmapheresis) separates the liquid component of blood from its cells, which are then returned to the donor. The collected plasma is used to create life-saving therapies and transfusions. However, for safety reasons, individuals who are pregnant are strictly deferred from donating plasma according to major regulatory guidelines.
Increased Physiological Demand on the Mother
Pregnancy involves significant changes to the circulatory system, including a substantial increase in blood volume, which can reach up to 50% above pre-pregnancy levels. This volume expansion is characterized by hemodilution, meaning plasma volume increases disproportionately more than red blood cell mass. Removing a large volume of plasma during donation can acutely stress a circulatory system already working harder to support the pregnancy.
Removing plasma also removes fluid and proteins, which can exacerbate gestational anemia. Anemia is often worsened by the depletion of iron and other nutrients necessary for blood production. The temporary reduction in total circulating volume following plasmapheresis can lead to symptoms like dizziness, lightheadedness, and dehydration. Avoiding this physiological stress is a primary reason for the deferral, prioritizing the mother’s health.
Potential Risks to the Developing Fetus
The developing fetus requires a stable and continuous supply of oxygen and nutrients delivered through the placenta. This delivery depends on maintaining sufficient maternal blood volume and pressure. The temporary removal of a significant volume of plasma during the donation procedure can momentarily reduce the mother’s circulating blood volume.
This reduction can pose a risk by momentarily decreasing placental perfusion, which is the blood flow to the placenta. Any reduction in this flow could potentially stress the fetus or compromise the balance of oxygen and nutrient transfer. Although the body quickly works to restore volume, any additional stress is avoided to ensure a stable environment for fetal growth.
Unique Risks Posed by Donor Plasma to Recipients
A primary reason for deferral relates to the safety of the plasma recipient. During pregnancy, the mother is exposed to the fetus’s paternally-inherited Human Leukocyte Antigens (HLA) as fetal cells cross the placental barrier. In response, the mother’s immune system may generate anti-HLA antibodies, which circulate in her plasma.
These antibodies, when transfused into a recipient, can trigger a rare but severe reaction called Transfusion-Related Acute Lung Injury (TRALI). TRALI is a leading cause of transfusion-related fatality, characterized by the sudden onset of acute respiratory distress. The anti-HLA antibodies mistakenly attack the recipient’s white blood cells, causing them to aggregate in the lungs and leading to acute pulmonary edema. Because of this risk, plasma from individuals with a history of pregnancy is often restricted from general transfusion use, or the donor must first be screened for the presence of these anti-leukocyte antibodies.
When Donation Can Safely Resume
Donation centers have specific regulatory timelines for when a person may safely resume donating plasma after childbirth. The standard waiting period is typically a minimum of six months after delivery. This deferral ensures the mother has fully recovered from the physiological demands of pregnancy and childbirth.
The waiting period allows time for the mother’s blood volume and iron stores to normalize, reducing the risk of complications such as anemia or dehydration during the donation process. Furthermore, some guidelines suggest waiting until the cessation of breastfeeding, as the donation procedure can temporarily affect fluid balance, which may impact milk supply. Before resuming donation, previously pregnant individuals are often required to undergo testing to ensure their plasma does not contain the anti-HLA antibodies linked to TRALI risk.