The most obvious signs of a successful fresh embryo transfer are early pregnancy reactions and elevated blood HCG levels. After a successful fresh embryo transfer, if the pregnancy is early there may be some obvious early pregnancy symptoms such as nausea, regurgitation, desire to vomit, breasts become soft and swollen, and a continuous elevation of blood HCG. Of these, the most accurate and reliable is the elevated blood HCG level. Fresh embryos are usually transferred from 3-day embryos grown in vitro or 5-day blastocysts, and these embryos can produce elevated blood HCG levels about 1 week after successful transfer, at which time a blood test can provide an early indication of whether or not a pregnancy is occurring. In addition, the increase in blood HCG level has a doubling effect, and it is recommended that the test be repeated at intervals of 2 days, rather than looking at one level alone.