Kerry and Jeffrey Mastera said it was a costly road but one well worth it."It's just the best thing ever," said Kerry Mastera.The Mastera's spent thousands of dollars on infertility treatments before finally giving birth to twin boys Max and Wes. They said the success of two had to do with choosing to have two embryos transferred instead of one.The boys were born premature and spent weeks in the hospital. The bill for their stay hovered somewhere around $1.2 million.The American Society for Reproductive Medicine will issue new guidelines next week encouraging families to avoid multiple births because of the costs often associated with it. They said there were also increased health concerns for the mother and children.Dr. William Schoolcraft, with the Colorado Center for Reproductive Medicine, said it's a shift from the typical guidelines that discourage triplets, quadruplets and so on."There is a progression of that philosophy to twins because they are at a higher risk and they are certainly more expensive. So we are asking, 'Can we just implant one embryo?'" said Schoolcraft.Schoolcraft said he encouraged patients to transfer only one but said it was a hard sell because people are financially invested and each treatment is costly."They want the better chance of getting success or the lower chance of failure that two embryos give them even though they realize twins are a possibility," said Schoolcraft.Kerry Mastera said she and her husband went for two for that very reason.She didn't think the lengthy hospitalization of her boys was a burden on the system and thinks they deserved the same love and care in the hospital as twins born spontaneously."People have spontaneous twins, triplets and sometimes even quadruplets. Even single births have complications that end up in NICU," said Kerry Mastera.