The choice of having a boy or girl was first made possible for patients who suffer from sex-linked diseases that can harm their child.  More recently, parents are choosing a certain gender to balance their families.  There are two techniques used to make gender selection possible, either the use of preimplantation genetic embryo screening (PGS) or sperm separation via microsort®.  Microsort® technology is based on the difference in size of the X and Y chromosomes (the X chromosome is slightly larger and heavier) within the sperm.   The effectiveness is less than 90% for sperm separation while it is greater than 99% with PGS.  Please be sure to discuss the options with your physician to learn more.