I often hear parents complain that they weren’t told their baby’s blood type at birth. I reassure them that there’s no good reason to know and that most hospitals don’t even run the test routinely any longer. Thirty years ago, blood type was a major issue. If, God forbid, you were in an accident and needed a transfusion, the hospital or paramedics had to rely on a card in your wallet that indicated your blood group; if they had to determine your blood type in real time, you might have been past needing the blood by the time they were done. Thanks to new technology, blood typing is now instantaneous, and as for that card, you can leave home without it.