answer:If you were having a child with the express purpose of trying to save someone else using bone marrow or cord blood, then I could see the point. However, if that was the case, you’d have genetically selected the correct embryo in the first place. Just because we were curious, last year, we bought home test kits to determine our daughter’s blood type. It was fun. Since my husband and I already knew ours, we used our blood to test the accuracy of the results. He he. This reminds me of your romance-book-no-period-pregnant question on Askville. That was a good one!