So, lets say you titrate all these OB samples. What is the doctor going to do with the info? Is he going to forego postnatal RhIG (heaven forbid)? Is he going to panic the mother that her baby will be sick? As long as the reactions are not strong and not detectable at some other phase than IAT, why not just see if the baby has a pos DAT? What are they going to do about it anyway, if it isn't detected until delivery? The point then will be to treat the baby based on if it is affected and how much. If they need to know for next pregnancy, then they should do a repeat Ab screen on the mom about 6 mo. post delivery. You might need to do further studies in the A+ baby of an O neg mom that has a pos DAT. Even then, a titer won't really clinch the case for you. The eluate will be of more use. I believe RhIG can sometimes cause a pos DAT in the baby, although probably more likely right after it is given than 3 mo. later. Of course, we must always err on the side of giving RhIG when it is not needed, rather than withholding it when it is.