PUBS stands for Percutaneous Umbilical cord Blood Sampling and FBS stands for Fetal Blood Sampling. All of these are names for a procedure where the doctor uses a needle to withdraw a blood sample from the umbilical cord and for NAIT pregnancies the purpose is to obtain a platelet count. If the count is low, they may transfuse with matched platelets. There are risks associated with the procedure that are generally stated as pretty low, but be careful to ask if the statistics being quoted are for the general population or ones involving NAIT. Some of the complication statistics I have seen in NAIT research seem much higher than the general population, possibly due babies being thrombocytopenic.