You can’t donate plasma while pregnant because of how your immune system handles pregnancy. As your baby grows, some of their blood gets into your blood vessels through the placenta. When that happens, your body makes human leukocyte antigens (HLAs) 1 .
HLAs help your body decide what belongs and what doesn’t. So if a bacteria or virus shows up, they know to fight them off. While these immune defenders won’t hurt you or the baby, they could harm 2 the person getting your plasma.
Most providers will tell you to wait until at least six weeks 3 after delivery to donate plasma. Your donation center might still check your blood for HLAs after that time. If you’re at all unsure, feel free to ask your healthcare provider. You’ll be eating those post-donation cookies in no time.